Gavin Colvert: Back to Nature: Aquinas and Ethical Naturalism


Back to Nature:
Aquinas and Ethical Naturalism

Gavin T. Colvert

There is no doubt that we are living in a moment of extraordinary development in the human capacity to decipher the rules and structures of matter, and in the consequent dominion of man over nature.  We all see the great advantages of this progress and we see more and more clearly the threat of destruction of nature by what we do…  The capacity to see the laws of material being makes us incapable of seeing the ethical message contained in being, a message that tradition calls lex naturalis, natural moral law. This word for many today is almost incomprehensible due to a concept of nature that is no longer metaphysical, but only empirical. [1]

In his recent addresses to groups of scientists and academics Pope Benedict XVI has been sounding a common theme: they ought to get back to nature.[2]  His concern cuts deeper to the core of modern life than simply the question of whether human beings are using natural resources responsibly.  As the Pope indicates, advances in empirical science and technology have enabled tremendous growth in our understanding of the structure of the physical world, including human biology. A paradoxical and unfortunate byproduct of these inherently worthy endeavors is that we have become less able to understand our own human nature, including its ethical implications, often referred to collectively as natural law ethics.  As a consequence, we stand in danger of eliminating human nature. 

Remarkably, other intellectuals, who share few of his presuppositions, agree with the Pope in this matter.  Francis Fukuyama, for instance, has argued that advances in chemistry and biotechnology will enable us to alter our nature so fundamentally that we need to speak of a “post-human future” unless we find the ethical and political principles to establish prudent boundaries for technological innovation.[3]  Our advances in scientific understanding, make it difficult for us to articulate these principles, because modern empirical methods challenge the traditional presuppositions of natural law ethics. 

In addition to those who worry about the eclipse of human nature, there are also theorists who share the Pope’s sense that we must return to nature in moral and political philosophy. Proponents of the new “Darwinian natural right,” for instance, hold that evolutionary theory is compatible with traditional Aristotelian teleology when it is properly understood.[4]  These arguments draw upon work by scientists who are prepared to admit the necessity of teleological explanations in biology. 

The effort to get back to nature in ethics and politics is a welcome development from the point of view of those who sympathize with the classical natural law tradition of reflection.  It forces us to rethink modern philosophy’s wholesale rejection of many traditional ethical presuppositions.  Furthermore, it offers hope that we may be able to find theoretical resources to avoid the grim “post-human future” envisioned by critics of contemporary culture as disparate as Benedict and Francis Fukuyama.  Given Benedict’s warning about the inadequacy of contemporary empirical scientific accounts of human nature, however, we must examine whether this retrieval of ethical naturalism can be successful.  For various reasons, we will conclude that it cannot succeed without alteration.  Furthermore, some account of the genuine challenges modern philosophy poses to the role of nature in ethics must be considered.  We may therefore ask three questions.  What are the historical sources of this debate?   What are the inadequacies of the recent ‘back to nature’ movement in moral philosophy?  Finally, can we get back to nature in ethics and politics while continuing to live in the contemporary world?

Defining Nature Down:

Eighteenth-century rationalism assumed that Natural Law was either discovered in Nature or a priori deduced by conceptual and rational knowledge... I submit that all the theories of Natural Law which have been offered since Grotius (and including Grotius) were spoiled by the disregard of the fact that Natural Law is known through inclination or connaturality, not through conceptual and rational knowledge.[5]

The renaissance of interest in nature's connection to the moral order would be welcome to students of classical natural law theory like Jacques Maritain.  Maritain also understood well why natural law ethics fell out of fashion.  Modern philosophy came to reject traditional reflection upon the ethical implications of human nature for several reasons.  First, there was the supposition, which was highly attractive to early modern thinkers, that modern thought represented a practical watershed over its merely theoretical pre-modern counterparts.  According to this view, science and technology would enable improvement of the human condition and make human beings masters of their own destiny.  From that vantage point, it could hardly seem appropriate that nature was the measure of human beings.  Second, developments in empirical and quantitative methods of analysis in natural philosophy called into question the role of natures and purposes (teleology) in scientific explanation.  Third, Humean and other forms of skepticism radically undermined claims regarding what we can know of human nature.  Fourth, key figures in the Enlightenment period were not satisfied with the apparent imprecision of traditional approaches to morality based upon the virtuous cognition of the agent.  This caused moral philosophers to seek other empirical and rational replacements for the role of nature in moral theory that were perceived to be more precise and therefore “scientific.”  As Maritain points out, the combination of these factors led to a much thinner empirical account of human nature and a distorted conception of natural law morality in the eighteenth and nineteenth centuries.

We owe the idea that scientific progress should make human beings masters of nature to figures such as Descartes and Bacon.  In his Discourse on Method, Descartes rejected the Aristotelian natural philosophy and metaphysics of his scholastic predecessors in favor of new empirical sciences, including physics and medicine.  His goal was to replace a putatively inaccurate and useless speculative philosophy, with a more useful practical one.[6]  Cartesian science and philosophy initiated a challenge to natural law ethics on two fronts.  First, empirical and quantitative accounts of nature would replace qualitative and teleological ones.  Descartes himself proposed that rational reflection could establish certain truths about the nature of the human soul.  This part of his program seemed increasingly untenable to those who came after him, especially Hume.  Second, our mastery of nature would quite literally enable human beings to live for an indefinitely long period of time.  There is no doubt that Descartes would have been an eager proponent of the contemporary biotechnological revolution, whether or not he would have been willing to embrace a post-human future.

The ethical effects of this intellectual and cultural transformation have been analyzed with depth and clarity by Rémi Brague in his recent book The Wisdom of the World.[7]  Brague’s thesis is that cosmology and ethics were necessarily intertwined for pre-modern thinkers, whereas they are disconnected for us.  As Brague puts it, “The modern cosmos is ethically indifferent.  The image of the world that emerged from physics after Copernicus, Galileo, and Newton is of a confluence of blind forces, where there is no place for consideration of the Good.”[8]  The natural order of the cosmos is perceived by moderns at the very least as indifferent and more often as quite imperfect and standing in need of improvement.[9]  One’s presence in the world is no longer a matter of ethical significance; an ethical obligation to conform to the natural order is therefore inconceivable.  Our existence and nature are bare empirical facts to which the forces of nature are absolutely indifferent.  Both immanent and extrinsic senses of teleological explanation are lost through a thin empirical conception of both human nature and the cosmos.  More strikingly, the blind forces of nature produce a very imperfect state.  Brague quotes John Stuart Mill: “The order of nature, in so far as unmodified by man, is such as no Being whose attributes are justice and benevolence would have made with the intention that his rational creatures should follow it as an example.”[10]  Given the putative imperfection of this state of affairs, one can understand the connection between Descartes’ technological imperative and the ethical implications of modernity.[11]  Modern inventions hold out the prospect that we may correct and improve the crudity of the natural world, including ourselves as natural artifacts, rather than conform to it.  The perfection or ultimately the annihilation of human nature appears to be a form of progress.

The vast difference between the classical and modern viewpoints can be illustrated by comparing the moral traditions initiated by Aristotle and the Bible over against that of an early modern thinker such as Thomas Hobbes.  Without diminishing their significant differences, the Bible and the Aristotelian corpus share important commonalities in their accounts of human nature.  According to both traditions human beings are members of a common natural kind, with common interests and purposes, capable of excellence through virtue, although they are capable of failing to achieve it.  In Aristotle’s case this excellence is grasped through a careful immanent teleological account of human beings in relation to the political community.  In the Nicomachean Ethics, for instance, Aristotle envisions a hierarchy of common human ends shared by members of the natural kind.[12]  In the Politics he adds that the political community is natural, and although it is posterior in the temporal order, it is prior in nature to the family and the individual. [13]  By this he means that human beings are by nature structured for and completed by life in the polis.  In the case of Genesis, human beings are said to be made in the image and likeness of God.  Prior to the Fall their existence is divinely intended to be a rich and happy one.  Later theological reflection will conclude that after the Fall human friendship with God is restored through divine grace.  Although by definition grace is gratuitous, it perfects nature rather than eliminating it.  So, the attainment of human perfection, though requiring assistance is still desired by and perfective of human nature.[14]  In spite of significant differences between these traditions, what they share is a qualitatively thick conception of the ethical implications of human nature.

In the Leviathan on the other hand, Hobbes offers a qualitatively thin empirical conception of human nature that is quite deliberately in opposition to both of the preceding traditions.  Using language and imagery reminiscent of the Biblical text of Genesis, the Introduction contrasts art and nature.  The state is emphatically a creation of human activity, rather than of natural or divine origin.[15]  The metaphors used are robotic as opposed to organic.  Hobbes goes on to describe human beings as naturally selfish and the political community as essentially unnatural.  His argument does not offer a contrary but equally thick qualitative account of nature; rather it constitutes a total rejection of the classical teleological approach.  Human selfishness is an empirically observable bare fact about human existence.  Furthermore, although he is willing to admit that human beings share common emotional responses by nature, the objects, purposes and goods beneath those responses are neither observable nor universally human:

…whosoever looketh into himself and considereth what he doth when he does think, opine, reason, hope, fear, etc., and upon what grounds; he shall thereby read and know what are the thoughts and passions of all other men upon the like occasions. I say the similitude of passions, which are the same in all men,- desire, fear, hope, etc.; not the similitude of the objects of the passions, which are the things desired, feared, hoped, etc.: for these the constitution individual, and particular education, do so vary…[16]

From Descartes’ mastery of nature to Hobbes’ robotic commonwealth we can begin to see how the thin empirical conception of nature that emerged in the modern era began to define nature down to the point at which it has become nearly impossible to undertake a critique of the trend toward our post-human future. 

Two important but ultimately unsuccessful kinds of responses from within modernity have attempted to provide a version of ethical cognitivism and a more complete account of ethical and political principles.  The utilitarian tradition, including Bentham and Mill, sought to replace Aristotle’s putatively imprecise and qualitative conception of human flourishing by deducing the moral good from a quasi-scientific maximization of an empirically observable quantity: pleasure.  Bentham’s appeal to a purely quantitative account of pleasures had the virtue of restricting itself to the thin empirical approach.  But, this virtue proved to be also a vice, since Bentham’s approach undermined the commonsense view that certain higher pleasures were qualitatively more valuable than lower ones that were more plentiful and easily obtained.  Recognizing this, Mill insisted upon a qualitative differentiation of human pleasures.[17]  His qualitative distinction, however, undermined the quantitative and empirical approach that was meant to replace Aristotle’s qualitative teleology.  Furthermore, the justification for his qualitative distinctions rested upon the unsatisfactory basis of expressed preferences, since he could not ground them in an underlying appeal to a common teleological conception of human nature.[18] 

On the opposite extreme, Kant’s approach sought to do for ethics (“laws of freedom”) what Newton had done for physics (“laws of nature”) by rational as opposed to merely empirical means.[19]  In the process Kant rejected the Aristotelian teleological conception of human nature and account of happiness as hopelessly vague and heteronomous.[20]  He proposed to replace this approach with a transcendental deduction of practical principles from the universal requirements of practical reason itself.  As Alasdair MacIntyre has pointed out, Kant flattened the conception of human nature to the single dimension of rationality, just as other moderns ended up with a thin empirical conception.[21]  Deriving the full requirements of the moral law from Kant’s philosophical defense of the Golden Rule has proved to be notoriously difficult.  As the observation from Jacques Maritain quoted above indicates, all of these approaches attempted to replace the classical account of moral principles with dubious appeals to rational and scientific modes inquiry in the wake of jettisoning the traditional conception of nature.

Art Imitates Nature?

Unicorn behind Fence

Plate 1: The Unicorn in Captivity, South Netherlands, 1495–1505 (Metropolitan Museum of Art).
(Click on images for full size)

As Rémi Brague has demonstrated, the modern tendency to define nature down has had profound cultural effects in terms of human beings’ abilities to understand themselves and the meaning of their existence in relation to the world.  A good way to illustrate just how far the impact of the intellectual shift in our conception of nature has penetrated broader culture is through the arts, and in particular visual art because of its rich capacity for carrying a narrative.  Even a relatively cursory and schematic examination of the differences between pre-modern and modern visual artworks reveals how changes in our conception of human nature have altered artists’ narratives.  As Aristotle asserted in the Physics, art imitates nature. [22]  To this we ought to add that art also follows our conception of nature, even in the modern case where art/craft is thought to transcend imitation of nature by mastering it.

Consider the example of two late medieval masterpieces in New York’s Metropolitan Museum of Art: The Unicorn Tapestries and the Merode Altarpiece by Roger Campin.  The Unicorn tapestries include seven separate wall hangings depicting the hunt for the mythical figure of the unicorn, which is both a symbol of fertility and a Christ figure in medieval art.[23]  The most famous individual piece (Plate 1) is the image of the unicorn in captivity, a stunningly beautiful panel which appears to complete the series of images, although previous panels show the hunt coming to a gruesome climax with the capture and killing of the unicorn (Plate 2).  The iconography of these images is contested, but the fact that the unicorn is alive in the final panel strongly suggests the motif of the risen Christ.  The astute viewer notices that there are eleven visible upright fence posts in this view, with a twelfth post either obscured or missing, possibly an allusion to Christ’s Apostles (the pillars) and more broadly to the Church.

Unicorn Hunt

Plate 2: The Unicorn Leaps across a Stream, South Netherlands, 1495–1505 (Metropolitan Museum of Art).

The unicorn is tethered inside the fence, although the fence is low.  It appears that he could easily escape.  His captivity is therefore very likely pleasurable and chosen.  On the other hand, the unicorn is located under a pomegranate tree laden with fruit.  This and other vegetation in the scene was strongly associated with fertility in the Middle Ages.  The unicorn is therefore also a symbol of fertility, procreation, the family, and especially in this case the beloved who has been captured by his lover.  Other iconographical clues in the narrative are consistent with this interpretation.  People gathered for the hunt are not dressed as hunters, but appear as if they might be guests at a wedding.  The initials of the patrons are woven into the fabric of the tapestries, which were perhaps wedding gifts.  How can these apparently disparate iconographical schemes fit together?  Scripturally, Christ is referred to as the bridegroom and his bride is the Church.  To the medieval viewer there was an evident connection between the natural order of human fulfillment through family life and the supernatural order of grace and salvation.  Whether we have described all of the contested details accurately or not, the makers of these images have indisputably produced a narrative in which the ethical implications of the natural and supernatural orders are seen to be closely intertwined with more ordinary surface appearances.


Plate 3: The Annunciation Triptych, Netherlands, ca. 1425, Robert Campin. (Metropolitan Museum of Art).

The Merode altarpiece (Plate 3), executed by the Flemish artist Roger Campin provides a similar though even more richly narrative case in point.  In addition to its fine aesthetic value, this unique triptych constitutes a veritable summa of medieval theological and ethical reflection.  Its smaller size and domestic context indicate that it was commissioned by a medieval burgher family for private devotion.[24]  The patrons kneel in the left hand panel, observing the model conduct of central figures and the significant event taking place in the other panels.  Family coats of arms appear in the windows of the central panel.  A typical Flemish city is seen in the background of the right hand panel.  The connection of the theological and ethical implications of this scene to ordinary life is unmistakable.  The image in the central panel is easily recognizable as that of the Annunciation of Christ’s birth to Mary by the angel Gabriel.  Mary’s betrothed husband Joseph, a carpenter, works with the tools of his trade in the right hand panel to fashion a mousetrap.  

Campin detail

Plate 4: The Annunciation Triptych (detail).

The image of the mousetrap is a familiar medieval trope drawn from Augustine’s Sermons.[25]  Christ’s cross provides the bait by which the devil’s dominance over fallen human nature is to be reversed by divine assistance.  The dignity and redemptive value of work is very possibly a theme intended by the artist.  Mary sits on the floor in the central panel, an indication of the virtue of humility.  She sits beside a scroll and book suggesting the combination of the Old and New Testaments.  The lily on the table and the boiling water in the background are common signs of her purity.  Barely visible to the naked eye (Plate 4) at the left is a small image of the Christ-child carrying a cross, flying through the glass window directly on a line with Mary’s ear.  The ear and the passage of light through glass are common metaphors for Mary’s virginal conception of the second Person of the Trinity, the Logos or Word.  Perhaps most remarkably, the astute observer recognizes that the image of the child descends upon seven distinct rays of light, one of a number of medieval images indicating the presence of the “Seven Gifts of the Holy Spirit,” which are supernatural counterparts of the great virtues.  The seven great virtues form the centerpiece of Thomas Aquinas’ structuring of his treatise on ethics and moral theology in the Second part of the Summa theologiae.  While the Merode altarpiece may contain distinctively medieval themes, its linkage of the moral dimensions of ordinary human life with cosmic events and principles is a classical move as Rémi Brague has demonstrated.[26]  Just as we find a qualitatively thick understanding of human nature and its ethical implications in pre-modern philosophical thought, pre-modern art resonates with rich narrative accounts of the ethical implications of natural and supernatural events.  It is remarkable to contrast this fulsome ‘perspective’ in pre-modern visual art, with some modern counterparts.

To say that modern art generally lacks either an ethical dimension or an interest in nature would be a gross error for two reasons.  First, the existence of a wide range of recent genres within the visual arts defies generalization.  Second, while some modern artists have eschewed naturalism and the didactic impulse in favor of a purely abstract aesthetic ideal, many have embraced one or both of these concerns.  Two examples of modern genres of visual art that have expressed distinctive interest in the natural world are the 19th and early 20th century movements of Realism/Naturalism and Impressionism.  Realists and Impressionists shared with their pre-modern counterparts an interest in representing nature, but they had very different conceptions of the human understanding of nature.[27]


Plate 5: Henri Gervex , Before the Operation, 1887 (Musée d’Orsay).

In the mid to late 1800’s Realists chose novel but mundane subjects for their paintings that were perceived initially by many to be shocking and even ugly.  Although the Merode altarpiece involved a domestic setting, with references to work and ordinary life, those references were elevated within the dramatic and moral purposes of the work.  Members of the Realist school portrayed ordinary subjects with a kind of empirical and quasi-scientific attention to naturalistic exactitude and minute detail, including in many cases the more unsavory aspects of modern life.  Thus, their subjects included poverty, disease, prostitution and the horrors of warfare.  Surely, some artists had ethical purposes in mind by calling attention to these subjects.  The question is whether their representation of the natural order itself was intended to manifest intrinsic ethical implications.  ‘Nature’ for the Realists is treated in a radically empirical and phenomenal manner.  An interesting example from this genre is Henri Gervex’s Before the Operation (Plate 5), which is found in the Musée d’Orsay in Paris.[28]  This image of a surgical procedure, which bears a likeness to Rembrandt’s Anatomy, adds numerous detailed touches including the display of the latest surgical instruments in the foreground.  With almost photo-realistic exactitude the artist recreates the objects and figures in the painting, paying close attention to light, shadow and authentic reproduction of the scene.  Compared to the detail of the Merode altarpiece, it is as if meticulous attention to the visible surface appearance of the natural world in Gervex’s painting has supplanted the qualitatively deeper but empirically less exact ‘perspective’ of the late medieval triptych.


Plate 6: Claude Monet, The Argenteuil Bridge, 1874 (Musée d’Orsay).

Not far from Gervex’s haunting canvas in the Musée d’Orsay, is a collection of Impressionist works by Claude Monet (Plate 6).  The Bridge at Argenteuil is an interesting example.  Impressionists reacted against the quasi-photographic exactitude of the Realists, but shared an abiding fascination with the natural world.  Monet’s method of capturing nature by seeing light and color, rather than by painting pre-conceived collections of objects, comes through very clearly in this painting.  The infinite range of colors and shadows reflected in the water, the bent image of the boats’ masts, and the color textures of the tree line in the background all convey the intensely subjective and phenomenal quality of Monet’s artwork.  From the point of view of the spectator, nature is once again immensely rich in terms of surface appearances, but little is understood of the deep structure of things; we do not penetrate through to their nature, essence or form. As Monet remarked to one viewer: “For me, a landscape does not exist in its own right, since its appearance changes at every moment; but its surroundings bring it to life, through the air and the light, which continually vary…”[29]

The purpose here has not been to make a careful and detailed assessment of either the iconography of medieval art or trends in modern painting.  Those endeavors would require greater detail and expertise.  Nevertheless, the outlines of a broader narrative are fairly clear.  The artists who created the Unicorn Tapestries and the Merode Altarpiece were able to see in the natural world and in human events profound ethical implications.  For them the whole of life was infused with a purposive ethical structure, which lay open to view for the careful observer.  While modern Realism and Impressionism show much more careful attention to either the empirical and quasi-scientific or phenomenal surface appearance of the natural world, the former qualitative depth has apparently disappeared from view.  As such, these artworks provide a graphic demonstration of Benedict’s assertion that modern technological and scientific modes culture may obscure the qualitatively deep ethical implications of our understanding of nature, even as it renders our grasp of empirical detail infinitely more rich and varied. 

The Modern Tribulations of Natural Law Theory

As we have already noted, Jacques Maritain’s complaint against both proponents and critics of natural law ethics in the 18th and 19th centuries was that they caricatured the traditional view.  In so doing they did not point out internal difficulties within the theory.  His observation has proved to be quite accurate.  It is now clear how such systematic misperception and transformation of traditional appeals to the role of nature in ethics could be possible.  As the modern understanding of nature changed, so did the understanding of the ethical implications of nature, and with this change arose awareness of the apparent impossibility of inferring moral norms from bare empirical facts. 

Two points in the modern conception of natural law struck Maritain as problematic: the appeal to a thin empirical and quasi-scientific account of nature, and the failure to recognize the importance of cognitive but non-algorithmic “connatural knowledge.”  We can trace the former view to thinkers such as Hobbes, who rejected the epistemic possibility of grasping shared natural potentialities or teleological descriptions, and recognized only appeals to shared emotional and behavioral responses.  The latter view is evident in thinkers such as John Stuart Mill, who relegated the idea of cognitive but non-discursive moral judgments to the role of suspect intuitions.  As he argued in Utilitarianism, particular moral judgments must always involve the application of a universal rule to a particular case. [30]  In this Mill was implicitly rejecting the classical Aristotelian emphasis upon the prudential judgment of the virtuous agent. This viewpoint was shared by Kant, who insisted that only rationally derived principles of good willing, not an appeal to an agent’s character, were adequate to determine the rightness or wrongness of a moral choice.[31]  Modern ethics is therefore generally rule-based, and is modeled upon the successes of early modern natural science in articulating precise hierarchical systems of predictive rules or “laws of nature.”

Fortunately, recent work in the foundations of ethics has begun to call these early modern presuppositions into question.  Some of this work owes its inspiration to Wittgenstein’s analysis of rule following, which challenged the notion that all rational applications of a norm are algorithmic or deductive. [32]  An important case in point is the British analytical philosopher John McDowell, who has quite consciously made an effort to rehabilitate Aristotle’s concept of virtuous judgment through the notion of a cognitive “sensitivity.”[33]  Aristotle’s idea of habituated practical understanding and Maritain’s category of “connatural knowledge,” which would have been dismissed at the mid-point of the 20th century as forms of discredited intuitionism, take on new significance in light of this work. 

Maritain’s assertion that modern versions of ethical naturalism have failed because they buy into a false empirical and pseudo-scientific conception of nature has also received support.  In his recent book, Ethics: Twelve Lectures on the Philosophy of Morality, the British philosopher David Wiggins notes that some of the most influential mid-twentieth century criticisms of ‘naturalism’ in ethics were directed at contemporary rather than classical conceptions of nature.  G.E. Moore’s principal concern, for instance, was utilitarianism’s specious “scientism.”[34]  Moore’s charge that versions of ethical naturalism commit the “naturalistic fallacy” was originally directed at Bentham and Mill’s claims that one could deduce particular conclusions about moral goodness from an empirical or quasi-empirical account of pleasure.  Wiggins observes, quoting Moore:

To understand this accusation, we first need to know what Moore meant by ‘nature’.  ‘By nature,’ Moore writes, ‘I do mean and have meant that which is the subject-matter of the natural sciences and also of psychology…  Naturalism in ethics not only seeks to define the indefinable.  By approaching good in the sort of terms Bentham and Mill had employed, naturalism approaches ethics in the wrong kind of terms.’ [sic][35]

Given Moore’s understanding of nature it is no wonder that he thought there was an insurmountable logical divide between facts about nature and moral norms.  The truth in Moore’s so-called “naturalistic fallacy,” misguided though it is in some ways, is that the relationship between human nature and the human good is more complex than merely being a calculus of human inclinations and desires.  What Maritain asserted was that, properly understood, Aristotelian and Thomistic ethical naturalism does not depend upon the deduction of moral imperatives from crudely empirical descriptions.  Curiously, Moore’s gift of the naturalistic fallacy to the analytical tradition in moral philosophy provided a key tool in the arsenal of modern efforts in the middle and latter part of the twentieth century to dismiss natural law ethics as outdated.

In addition, towards the latter part of the 20th century, the significance of the critiques of ethical naturalism by figures such as G.E. Moore and earlier David Hume came to be felt very firmly within the natural law tradition itself.  That event prompted various responses.  Some natural law ethicists organized efforts to show that natural law theory was not guilty of violating the ‘fact/value’ distinction.  The most important such effort is often referred to as ‘New Natural Law Theory’ or more disparagingly as ‘natural law without nature,’ since its proponents reject the idea that the moral ought can be deduced from descriptive propositions about human nature alone.  There is truth in this view, especially if one considers descriptive propositions about nature to be limited in the way that Moore did.  Others in the Thomistic tradition simply rejected the idea that Aquinas was a natural law theorist.  They argued instead for a sort of Aristotelian virtue ethics in Aquinas that appealed to habituated moral cognition, but deemphasized moral absolutes and tended towards moral particularism and even relativism.[36] 

Such was the state of ethical naturalism, including the study of Aquinas’ natural law theory, towards the latter part of the last century.  Two significant recent developments have changed this situation dramatically.  Within the Post-Positivist analytical tradition of moral philosophy some rethinking of the rigid distinction between fact and value has taken place.  Proponents of a so-called new ‘moral realism’ argue that the dichotomy between fact and value is analogous to the distinction between descriptions in the sciences and social sciences.  Just as psychological and biological descriptions are factual, although not reducible to physical descriptions; moral language may be factual though not reducible to descriptive terms.  Numerous contemporary theorists have concluded that Moore and Hume’s arguments cannot bear the logical weight they were originally thought to carry. 

In addition, study in the area of Neo-Darwinian biology, including ethical and political reflection upon the implications of this thinking, has undergone some important shifts, which has led to the development of a renewed interest in ethical naturalism from within the scientific community.  Proponents of a theory of ‘Darwinian natural right’, such as Larry Arnhart, suggest that Darwinism can accommodate the traditional role of nature in ethics and provide a defense of a fairly traditional conception of morality without appeal to traditional religious concepts. This renewed extramural interest in ethical naturalism has caught the attention of those within the natural law tradition looking to revitalize the role of nature in ethics, some of whom embrace elements of the Darwinian approach.  An important concern with this approach, however, is that appeals to the evolutionary naturalist basis of ethics will lead us back to the deplorable scientism repudiated by both Maritain and Moore.  In addition, it is very uncertain that Neo-Darwinian ethical naturalism can preserve all of the appropriately elevating principles and institutions fostered by the older teleological conception of nature.  

The purpose of the considerations that follow is to point towards the establishment of the appropriate role of human nature in ethical and political reflection.  No definitive solution to this problem is offered, only the initiation of a promising line of inquiry, rooted in the philosophy of Thomas Aquinas.  This line of inquiry depends upon two avenues of reflection.  The first avenue considers what can be learned from recent arguments for and against the fact/value dichotomy and whether they can be reconciled with Aquinas’ account of the status of the primary principles of the natural law.  Contrary to some recent work in natural law theory, careful study of recent developments in the field demonstrates we should reject the stronger forms of the claim that moral evaluations do not depend upon facts about human nature.  The common sense reading of Aquinas’ ethics also presupposes a relation of dependence between ethics and theoretical knowledge.  But, at the same time, we should not claim that ethics is deduced from metaphysics and philosophical anthropology, as some students of Aquinas’ ethics have thought.  Ethics does not reduce to metaphysics or some other science.  The second avenue of inquiry aims to assess the significance of the alternative view of ethical naturalism presented by ‘Darwinian natural right’ theory.  Observing the pitfalls in this alternative approach is an important exercise for proponents of natural law theory who ought to avoid accepting uncritically any form of ethical naturalism that purports to ground morality in human nature and human inclinations.

The Case for and against the ‘The Naturalistic Fallacy’

There are two important sources for the fact/value distinction, Hume’s Treatise of Human Nature[37] and G.E. Moore’s Principia EthicaMoore claimed that good is an indefinable, non-natural property, and that those who attempt to define good in terms of natural properties commit the ‘naturalistic fallacy’.[38]  Hume’s paramount concern was with the distinctive character of practical judgment as action-guiding.[39]  Hume remarks that if moral judgments were not action guiding there would be no point in studying or teaching morality.[40]  He formulates a deceptively simple syllogism to capture his viewpoint: ‘Morality is action-guiding, reason is impotent, therefore morality is not derived from reason’.[41]  The primary gap for Hume is therefore between the action-guidingness of practical reason and the descriptive role of theoretical reason.  This concern is shared in a qualified way by classical Aristotelians such as Aquinas.

A more radical claim about the diversity of fact and value is actually made by G.E. Moore, who argues that moral and non-moral terms cannot be inter-definable or synonymous.  Moore proposed the “open question argument” as a test for the synonymous character or reducibility of moral and descriptive language.  According to this test, whenever the identical meaning of two terms can be questioned, such as ‘good’ and ‘pleasurable’, we cannot infer the one from the other.  Moore argued that this test applies to every attempted naturalistic reduction of moral predicates, including utilitarianism and Neo-Darwinism.  If, for instance, we regard the good as pleasure, we may ask whether anything is good in virtue of producing pleasure.  Since this is always open to dispute, Moore argued good could not be synonymous with or reduced to any natural property. 

The ‘open-question argument’ points to an indisputable truth about moral and descriptive language.  The connection between descriptive facts and moral goods is not universally transparent.  Aquinas actually discusses this point himself on occasion when he argues that certain moral principles are not per se nota or self-evident to everyone.  This does not entail that facts and values are utterly diverse, however, since two terms may have their meaning fixed with respect to each other without the connection between them being transparent.  Moore’s argument fails to account for the possibility of semantic depth—or unrecognized levels of meaning.  It requires that competent speakers be able to recognize any and all synonymous terms once they are familiar with the terms under discussion.[42]  This overly simple view of meaning precludes the possibility that we may discover through analysis and experience greater depth of meaning to terms with which we are already familiar, because we come to appreciate the deep structure of reality through reflection and activity.[43] 

A good example of how this may take place in the case of ethical reflection is to be found in Aristotle’s dialectical inquiry into the nature of the human good in the Nicomachean Ethics.  Aristotle maintains that the human good depends upon the human function, which is given by our nature.[44]  But, an appreciation of our nature and the goodness of certain possibilities for human fulfillment must come from the practice of the virtues.  It is by repeating the acts of the virtues that we come to acquire a cognitive appreciation for the point of those activities as perfections of our nature.  We are not merely socialized.  Virtues are cognitive dispositions. 

Reflection upon the status of Moore’s “naturalistic fallacy” shows us that the issue of the relationship between descriptive and evaluative discourse is part of a more general problem concerning also the relationship of any two descriptive discourses. Unless we intend to hold that all rational discourse must be reduced to a single univocal subject matter, it turns out that Moore’s account will render impossible movement back and forth between various sciences as making factual claims.  It must therefore be rejected.  For instance, without reducing psychological descriptions to biological descriptions, and biological descriptions to chemical ones, and chemical descriptions to physics, it is clear that psychology depends upon biology, chemistry and physics.  But, the relationship between these sciences is not a strictly deductive one.  Furthermore, psychology as a science cannot be subsumed into biology and these two sciences cannot further be subsumed into physics.  Some have suggested that psychology can be reduced to chemistry, and perhaps even to physics.  Thus, physicists could deduce psychological conclusions with properly physical principles alone.  But, this project has not proved to be successful. Psychological descriptions are in some measure irreducible to biological, chemical or physical descriptions, even though the former depend upon the latter.

This suggests a note of caution for both those who would maintain a radical distinction between fact and value, and those who would simply dismiss Moore’s analyses.  Just because factual and evaluative discourse do not appear to pass Moore’s test, does not entail that a relationship of dependence between them is lacking.  Moral norms do appear to depend upon the kind of beings that we are, even if the relationship of dependence is open to question and inquiry.  This is consistent with Thomas Aquinas’ assertion that moral facts and physical facts are not distinct in reality, but differ in intelligible content or ratio, because in some sense moral facts just are physical facts. [45]  On the other hand, the efforts by some natural law theorists to ‘reduce’ ethics to metaphysics or anthropology are not unlike the effort to reduce psychology to physics.  An ontological relationship of dependence between the subject matters of these various bodies of knowledge does not license or entail a reduction.  Moore was over-zealous in drawing out the implications of his principle.  But, there is an important sense in which ethical principles are discovered and defended within ethics, just as psychology has its own proximate principles and subject matter.

Consider the claim that we can deduce physics from metaphysics.  Surely physics depends upon metaphysics, but the integration of metaphysical principles into physical science does not imply a mere deduction of principles in physics from metaphysics.  There is a danger of falling into a mistaken view on both sides of this situation.  These observations are compatible with the Aristotelian view of the relationship between various sciences, in which the principles of a lower science depend upon the higher, but the sciences remain distinct because proper principles of a particular science must be co-assumed (as bridging premises) with the principles demonstrated in the higher science.[46]

Aquinas’s View of the Relationship Between Ethics and Human Nature: The Foundational Principles of the Natural Law

Consideration of G.E. Moore’s ‘naturalistic fallacy’ has shown that his speculation does not warrant the complete diversity of factual and ethical discourse although it does suggest the distinctness of the domain of ethical inquiry.  We do not immediately perceive, nor can we merely deduce the relationship between moral norms and descriptive facts from a cursory examination of the empirical data.  Crudely empirical descriptions of human capacities and desires do not allow us to read our moral obligations from a merely descriptive account of human nature.  This was Moore’s concern with utilitarianism, and at another point in Principia Ethica with Neo-Darwinian biology.  While Moore was wrong to assert an impassible logical gulf between normative ethics and our understanding of human nature, he was right to insist that there was something wrong with the crude scientism of his day. 

The approach to human nature and ethical naturalism in early modern philosophy has a history that distinguishes it in important ways from classical ethical naturalism, and indeed from classical philosophical anthropology and metaphysics.  What is crucial to the modern understanding is the replacement of an account of the function or perfection of human nature, which defines its essence or purpose (teleology), by a merely descriptive account of an empirical given.  As we have seen, Hobbes insists in the Leviathan that human beings share in virtue of their common nature certain passions (or emotions) like desire, fear and anger; but not the objects or purposes of those emotions.  Our incapacity according to Hume to discover the secret purposes of nature, gives way to a surface empirical account, which like the case of the Impressionist studying light and color does not allow discernment of a deeper narrative beneath the surface appearances.  The present analysis contends that Aquinas’ account of the role of human nature in ethical and political theory is innocent of the legitimate concerns raised by figures like Moore and Hume, but that some other contemporary efforts to revive ethical naturalism, such as the new Darwinian natural right theory, face serious obstacles because they share modern philosophy’s surface empirical account of the connection between human nature and the human good.

We can begin to get an understanding of Aquinas’ particular version of ethical naturalism by looking at his view of the relationship between ethical first principles and theoretical knowledge.  For the purpose of illustration we may consider a single key passage in Aquinas’ Summa theologiae (ST I-II.94.2) that has been the subject of a great deal of controversy over the last half century or so.  The passage contains Thomas’ most well known treatment of the relationship between practical and theoretical knowledge.  Interpretations of this passage have ranged from the view that ethical principles are part of a subordinate science deduced from metaphysics and philosophical psychology, to the view that practical reason is completely autonomous.  It is not difficult to see that the disputed interpretations of this passage have been deeply influenced by modern criticism of ethical naturalism by figures such as Hume, Kant and Moore.  The truth of the matter is that that Aquinas’ position is somewhere in between these extremes.

Three key points in ST I-II.94.2 need clarification: (1) how the natural law is consequent to human nature, (2) precisely what relation the First Principle of Practical Reason (FPPR) bears to the Principle of Non-Contradiction (PNC) and other theoretical principles, and (3) in what sense the natural law is founded upon the rational character of goodness and upon human inclinations.  We can investigate the first and third points by examining the second objection to the article. 

Question 94.2 poses a remarkably contemporary problem if we pause to think about its central thesis: that the natural law is composed of a single precept or norm in one sense, and in another sense it is composed of many.  Aquinas evidently has in mind here the complex and sometimes contradictory character of the natural motivations to action within persons.  For example, human beings have both deeply rooted cooperative and competitive tendencies that render us both fiercely loyal and also sometimes treacherous.  How can both altruism and egoism be natural, and there be a consistent ethic rooted in human nature?  Aquinas is also aware of the diversity of cultural forms between groups of persons.  In what ways are various cultural forms rooted in human nature without implying ethical relativism?  Without denying the complexity of human nature, and the grounding of ethics and politics in the variety of cultural customs, Aquinas’ purpose is to argue that human nature provides a common basis for ethical universals. 

The purpose of the hypothetical question Aquinas poses to himself in the second objection is to argue that the natural law can be composed of only one precept, because otherwise it would involve any human inclination whatsoever, including any particular human desire.  The unstated presumption is that such desires are often conflicting, and are even the source of vicious conduct.  The objection formulates at least two relevant concerns: to protect the rational character of the natural law and to preserve it against the charge that many kinds of immoral behavior could be justified under the guise of natural desires.  In formulating this objection, Aquinas shows that he is aware of the danger of allowing ethical naturalism to be described in crudely physicalistic terms.  He anticipates the sort of concern that Moore had with consequentialism and also certain difficulties associated with contemporary attempts by evolutionary psychologists to account for moral norms strictly in terms of natural selection. 

Aquinas does not mention any particular example in Objection 2, but the context makes it clear that he is aware of these kinds of problems.  His response to the objection affirms that every human inclination, including those of the passions, belongs to the natural law, insofar as they are all “regulated by reason” and are thus “reduced to one first precept.”  In this sense he says there are many precepts that share a common “root.”  Aquinas thus rejects a crudely empirical account of human inclinations in favor of one in which natural desires acquire normative significance in the context of a reasonable assessment of their mutual ordering to the human good.  Clearly, natural law is rooted in nature for Aquinas, but is not merely deduced from a surface account of human inclinations.  Aquinas can make this move because his account of human nature presupposes an understanding of its deeper structure.  The human good is not merely equated with an empirical account of the satisfaction of our given desires, but in terms of how desire and reason can shape a perfected form of human existence.

We can see Aquinas putting the fruits of this approach into effect in his discussion of matrimony in Book 3, Chapters 122-125 of the Summa contra gentiles.  In that passage he proposes to himself the kinds of considerations advanced by evolutionary psychologists as justification for the dissolubility of marriage.  According to such theorists, we can infer a temporary but not a permanent basis for marital fidelity from the male’s genetic interest in establishing paternity.[47]  For Aquinas, however, the natural good of human sexual desire and activity must be understood not only in terms of the ability to reproduce, but in terms of the ultimate end toward which reproduction is ordered.  Children require nurture and flourish in a society where they experience the permanent love and concern of their parents.  Aquinas asserts ‘serial monogamy’ is contrary to justice because it does not respect fairness and equality of the husband towards the wife.  Finally, marriage is said to be the highest kind of friendship, and the intrinsic good of this virtuous activity cannot be established without the permanence of indissoluble unions.

A similar pattern of argumentation is offered in Chapter 129, where Aquinas develops the thesis that certain actions are good or evil according to nature.  He argues from the inclination of natural sociability to the affirmative precepts of justice and the negative precept of non-maleficence.  Evolutionary naturalists have noted the difficulty in deriving other regarding justice and universal requirements associated with human rights from our cooperative tendencies, since competitive inclinations also have a natural evolutionary basis.  While he is not ignorant of this point, Aquinas argues in response that cooperative and competitive inclinations are given meaning in the broader context of their contribution to human fullness of being.  We are clearly very far from a crudely physicalistic derivation of the norms of the natural law from nature at this point.  Aquinas thinks the raw data of the inclinations must be subsumed into a comprehensive understanding of the good life in order to appreciate their full significance and limits.  We may or may not agree with his particular arguments, but it is clear that his appeal to the natural inclinations is complex and sophisticated.  It should also be clear that such interpretation can only be completed in the context of a broadly evaluative as well as descriptive account of human life.

The other major interpretative issue at the heart of Question 94.2 is how Aquinas intends to characterize the relationship between theoretical and practical first principles.  It is clear that this relationship is crucially relevant to the question of the connection between ethics and our knowledge of human nature.  Here we can make a few pertinent observations about some points in the body of the article. 

Both theoretical and practical first principles are naturally known, per se nota or self-evident and indemonstrable according to Aquinas.  It is important to stress that “indemonstrable” is a technical term here referring to the idea of syllogistic demonstration.  There is a broader sense of demonstration, or defense by elenchus or reductio ad absurdum proof strategy that can be used to show the truth of first principles for Aquinas.[48]  We do not deduce first principles, since they are firsts, but we can show they are undeniably true.  Whatever Aquinas means by the term per se nota (self-evident), it is clear that the first principles of ethics are not proper conclusions deduced from some other principles.  The sense in which practical first principles are “founded” upon theoretical ones is thus not one of straightforward deduction.  It is also true that for Aquinas our self-evident grasp of first principles can be at first fairly inchoate or lacking in specificity.  That is, we only see into the deep structure of first principles as first and universal at the end of the process of moral reflection rather than at the beginning.  Initially, we recognize them only as principles in a concrete and more particular sense.  Aristotle suggests a similar model, when he asserts that we acquire the virtues as we begin to grasp the point of the activities to which we have been habituated.  Self evident principles need not be fully formed a priori intuitions. 

A second important point is that the plain sense of the text suggests a relationship of dependence between the first practical principle (FPPR) and the first theoretical principle, the Principle of Non-contradiction (PNC).  Aquinas says that an understanding of being is included in everything we apprehend.  The first theoretical principle, the PNC, is founded upon the nature of being and non-being and all other principles are founded upon it.  Just as the plain sense of the text leads us to believe that primary practical principles are not proper conclusions, because they are indemonstrable, the plain sense of the text leads us to deny that the practical and theoretical orders are completely diverse—contrary to the arguments of contemporaries such as G.E. Moore.  The Principle of Non-Contradiction functions as a requirement of rationality and consistency in ethical thinking as much as it does in other areas, even if ethical rationality and consistency requires the FPPR as well.  Furthermore, theoretical propositions may enter into practical argumentation as premises of ethical arguments, when they are combined with evaluative bridging premises.  An analogy with biological and psychological descriptions may be helpful at this point.  We do not conclude that psychology can be reduced to biology merely because premises about biological facts of the matter can function directly in psychological argumentation.

The really crucial issue at stake between competing interpretations of Aquinas’ account of the relationship of practical and theoretical principles is ultimately not the question of whether ethics ‘depends’ upon theoretical knowledge such as metaphysics and philosophical anthropology.  The plain sense of the text requires that this is true.  The real issue is whether we think that certain ethical principles, specifically those grounded in human beings’ natural desires and inclinations are founded upon a strictly or even primarily theoretical knowledge of human nature.  Aquinas is more confident than present day successors of Hume and Moore that the deep structure of reality permits the grasp of evaluative implications in descriptive concepts.  This situation is analogous to the arguments made by some contemporary philosophers that certain descriptive concepts like ‘danger’ have a ‘thick structure’ that implies an evaluation.  At the same time, a consideration of Aquinas’ account of how specific norms are rooted in human inclinations shows that crudely empirical descriptive accounts of the inclinations as such are too thin to serve as a basis for specific moral norms.  We come to grasp the full moral significance of our natural desires and inclinations only in light of a broader conception of the full range of the possibilities for human fulfillment.  The point is bound to be controversial, but it seems clear that the working out of our understanding the good of human nature is both practical as well as theoretical.  A part of this understanding includes recognition of the fact that virtues such as temperance, justice and friendship are intrinsically worthy aspects of human fulfillment, not merely instrumentally valuable as serving the needs of particular inclination.  Natural desires and inclinations may in some cases lead away from virtues like temperance and justice, unless they are tempered by reflection that places them into the context of full human good.  Marriage and our natural sexual desires provide a good example of this point. 

From the foregoing considerations it is clear that Aquinas is an ethical naturalist in the sense that he believes concrete moral norms for human conduct depend upon the type of beings that we are, which is given by our human nature and the possibilities for human fulfillment specified by that nature.  But, as we have seen from Aquinas’ discussion of straightforward attempts to derive specific norms from human desires and inclinations, reaching practical principles from descriptive knowledge of these inclinations requires placing that knowledge in the context of a broader appreciation of how the inclinations contribute to human perfection or fullness of being.  Furthermore, we cannot simply deduce how to integrate our natural desires and inclinations into human full-being from some antecedent descriptive facts about our nature.  We must understand the object or point of those inclinations as indicating some possibility for human fulfillment.  That is, reason must integrate the objects of natural desire into a coherent understanding of the human good. 

In order to appreciate fully the natural goodness of the inclination to human sexual activity, for example, as grounding norms concerning marriage and human sexual relations, we need to understand that sexual activity finds it full meaning in marriage and family life, as well as that friendship is an intrinsic fulfillment of persons.  Divorce is contrary to the goods that place the natural inclination to sexual relations in a fuller human context.  Without this understanding of the deep structure and meaning of human sexual relationships, we would fail to appreciate the moral significance of our natural inclinations.  Otherwise, if the natural inclinations were to be looked at in abstraction from this broader context, the male tendency towards sexual promiscuity would appear to license infidelity and no-fault divorce.  A just estimate of the relationship between human nature and ethics from the theoretical point of view suggests that ethics depends upon human nature, but that it is not exhausted by a kind of crudely empirical account of nature.  Classical ethical naturalism, such as that of Aquinas, could provide a richer account of the relationship of human nature to ethics, because it presupposed that inquiry into human nature was deeper than a surface empirical account, and included a teleological or purposive account of nature.  It remains to be seen whether contemporary attempts to revive ethical naturalism fair as well.


Human Nature and Political Theory

The preceding examination of Aquinas’ treatment of practical principles demonstrates that he thinks ethics depends upon human nature, and that practical knowledge depends upon theoretical knowledge in several respects.  There is a danger, however, of overstating this point about Aquinas’ moral philosophy.  For Aquinas, human nature and our natural inclinations have normative significance within a broader context that includes the integration of our basic desires into an understanding of the human good.  For example, we come to see the normative weight of our natural inclinations in light of their relationship to the intrinsic goodness of virtues such as justice and friendship.  Neither the goods nor the virtues are grasped by a priori rational intuitions.  They are expressions of undeniably good possibilities for human fulfillment that are only understood fully through experience and reflection upon activity. 

Thus, we cannot deduce a complete system of normative principles from a bare set of empirical descriptions of human nature, nor even from a simple enumeration of natural inclinations.  Indeed, the concept of a natural inclination’s naturalness must be understood in light of our overall grasp of the human good and cannot be reduced merely to a commonly expressed behavioral pattern as Hobbes suggested.  In many cases, habituation must correct or at least shape certain typical attitudinal or behavioral responses commonly exhibited by immature persons.  It is for this reason that contemporary natural law ethicists such as John Finnis have suggested that our grasp of human nature is practical as opposed to merely theoretical.  Facts about the deep structure of human nature are only grasped fully in light of reflection upon what goods constitute genuine possibilities for human fulfillment.  It is useful to complement this abstract argument in the foundations of ethics with a concrete political consideration of the role of nature in politics. This alternative approach will lead us to the same conclusion from a complementary vantage point. 

For Aquinas, moral and political philosophy are two species of a single broader genus having to do with conduct ordered to the human good.  Politics adds some further dimensions to ethical considerations.  For instance, politics has to do with the realm of positive law.  Aquinas points out in ST I-II.95 that while some concrete moral and political norms, such as the prohibition against killing the innocent, can be derived directly from fundamental general principles, others are specifications of those principles in ways that admit of multiple different instantiations.[49]  For instance, while the requirements of justice include certain concrete moral absolutes prohibiting injustice, justice with respect to property rights in a particular society depends in part upon custom and particular social arrangements.  The irreducible role of custom and political prudence should not be underestimated when enumerating the factors that ought to shape social and political life.  A certain gap between nature and concrete political norms is to be expected, since there are multiple ways of realizing individual possibilities for human fulfillment.  The relationship between human nature and moral and political goods is complex, though not merely relative.  We should therefore expect that sound political theory would lead us to recognize both the dependence of concrete political norms upon human nature, and also room for variation.  Political life in the final analysis cannot be reduced to either nature alone or nurture alone. 

In order to develop this argument it is appropriate to examine recent efforts in political theory to revive the normative significance of human nature as a source of concrete political norms contrary to contract theory and social constructionism.  The most significant recent effort in this area is referred to by its proponents as a theory of ‘Darwinian natural right’.  This examination will lead to two sorts of conclusions: first, Darwinian evolutionary naturalism is an inadequate though instructive approach to ethical and political theory, and second the lessons that can be learned from studying it help us to understand the complex relationship between nature and politics.


Neo-Darwinian Ethical Naturalism

Proponents of the theory of ‘Darwinian natural right’ provide an excellent example of a contemporary attempt to restore ethical and political naturalism outside the natural law tradition.  Neo-Darwinian naturalism in political theory draws upon the work of a group of biologists and evolutionary psychologists who reject the claim that evolutionary theory supports ethical egoism and social contract theory or moral relativism.  They argue that human cooperative tendencies are explicable and required by a careful study of the mechanisms of evolution.  Political theorists, drawing upon the work of these natural and social scientists argue that traditional concepts such as justice and even altruism can be defended from an evolutionary perspective.  In addition, according to these thinkers liberal democracy can dispense with the religious foundations of morality and replace them with an appeal to evolutionary science as a means of preserving and fostering cherished liberal political institutions, like democratic government, personal autonomy and individual rights. 

Evolutionary theory putatively supports a form of ethical naturalism because it shows that evolved human inclinations and desires foster cooperative social behaviors that confer adaptive advantages in natural selection.  Darwinian natural right theorists conclude that modern liberal theory may turn to evolutionary naturalism in place of its Christian religious roots for a number of reasons.  While some assert that evolutionary theory is not incompatible with monotheistic religion, others maintain that religious accounts of morality are simply false and exist in deep tension with the basic pleasure seeking tendencies inherent in liberal democracies.  Nevertheless, they maintain that evolutionary explanations offer a defense of moral and political norms that is basically traditional, defending the status of our cooperative and socially oriented tendencies as the basis for certain natural norms, contrary to the assumptions of earlier Social Darwinism. 

An influential representative of this position in political theory is Larry Arnhart, whose book Darwinian Natural Right: The Biological Ethics of Human Nature offers a comprehensive treatment of the subject.[50]  His work draws upon earlier scholarship in the natural and social sciences, as well as in political theory.  While Arnhart’s position is certainly not unique, he is an able defender of the idea that Darwinian ethical naturalism should be seen as belonging to a fairly continuous tradition of reflection that includes Aristotle and David Hume.[51]  This pairing might seem odd, since Hume is known for his innovative views in the foundations of ethics, which have tended to undermine the traditional conception of practical reason.  With the possible exception of Hume’s position on suicide, however, his moral conclusions are generally traditional.  Like Aristotle, as Arnhart points out, Hume also argues that desire is an important component of moral reflection and judgment.  Furthermore, Arnhart defends the idea that evolutionary naturalism supports traditional social institutions such as marriage and the family.[52]

For Arnhart, the content of Darwinian natural right morality is therefore essentially conservative.  He is eager to defend evolutionary naturalism against ethical and political theorists, like Peter Singer, who think that Darwinian morality requires a more liberal or even leftist program. [53]  Some of Singer’s more avante garde positions are well known, like his defense of infanticide under certain circumstances and his claim that people ought to be prepared to give up any wealth in excess of a minimal threshold for the sake of the greater good.  Arnhart discounts these views as incompatible with Darwinian ethical naturalism because they involve the denial of genuine restraints upon ethical and political conduct imposed by human nature:

The real source of this confusion is not Singer's Darwinism but his leftism. As Singer indicates in A Darwinian Left, the Left has traditionally believed that human nature is so malleable that it can be shaped in almost any direction; therefore social problems can be solved through utopian programs that would make human nature conform to rational norms of social harmony.[54]

Utopian liberals either ignore that human nature gives us both cooperative and competitive tendencies, or they think that such tendencies ought not to be normative because they can be overcome in the service of some other rational principle such as utilitarian maximization.  But, Arnhart reminds us that while our cooperative inclinations support sacrifice for the good of a group, competitive tendencies naturally constrain the focus of our concern to those who are more or less proximate.  Evolutionary naturalism can support self-sacrifice, which is not identical with the kind of moral universalism and self-negation required by the principle of utility.[55]  Failing to recognize the normative value of nature and natural inclinations, and thinking that we can subordinate nature to utopian social aspirations can lead us to implausible and repugnant conclusions, such as that we should overcome our natural revulsion to infanticide.  Arnhart, on the other hand, defends the view that enduring standards of right and wrong, including our aversion to infanticide, and support for marriage and the family are rooted in natural instincts that confer advantages in the process of natural selection.  He concludes that evolutionary ethics therefore supports a fairly traditional form of virtue ethics, and that it belongs in the tradition of classical ethical naturalists such as Aristotle and Aquinas.[56]

Like some contemporary proponents of Thomistic natural law ethics, Arnhart recognizes that one of the most significant intellectual obstacles to the acceptance of his theory of Darwinian natural right is the so-called fact/value dichotomy and the naturalistic fallacy.[57]  Many social scientists have accepted the assertions of mid 20th century analytical philosophers that there is an unbridgeable logical gap between empirical facts and moral evaluations.  The fact/value distinction is often called “Hume’s law” because the view that moral judgments are not judgments of fact is attributed to Hume as its original source.[58]  Arnhart thinks this view of Hume of as an ethical anti-naturalist is mistaken, and that Hume is closer to the Aristotelian position than many people are willing to acknowledge.[59]  His argument against the stereotypical classification of Hume is twofold: first, he asserts that Hume does not deny moral judgments are factual, as long we understand correctly the facts that they report, and second the real author who ought to bear responsibility for the fact/value distinction as we know it is Kant. 

Arnhart points out that Hume thinks moral judgments are factual in the sense that they report certain “species-typical pattern[s] of moral sentiments in specified circumstances.”[60] Upon this basis he can argue that for Hume moral judgments are grounded in human nature.  He distinguishes “cosmic objectivity,” “emotive subjectivity,” and “intersubjective objectivity.”[61]  Moral judgments lack cosmic objectivity because they are not true independently of the facts of certain shared human desires, nor are they just relative to a particular person’s subjective emotional state.  Moral norms are rather dependent upon human desires that are shared across the species.  Arnhart appeals to Hume’s comparison of moral judgment to secondary quality perception in order to make sense of this claim: “Vice and virtue, therefore, may be compar’d to sounds, colors, heat and cold, which, according to modern philosophy, are not qualities in objects, but perceptions in the mind…”[62]  Just as the color red is said to be a power of objects to induce in the spectator the experience of seeing red, so vicious behavior is said to be the power of inducing the sentiment of disapproval in the agent.[63]  We can be mistaken about a particular moral judgment, just as we can be mistaken about seeing a particular color, because we can be mistaken about what the species-typical sentimental response would be in a particular situation.  This species-typical response is a fact of the matter accessible to reason, but the moral sentiment itself and its normative force is not derived from reason.  Moral norms are therefore factual insofar as reason can judge of moral sentiment, but reason itself cannot motivate.[64] 

Even more remarkable than his reading of Hume is Arnhart’s suggestion that Hume and Aristotle agree fundamentally about the structure of practical judgment and its normative force.[65]  Arnhart quotes Aristotle’s assertion that “thought by itself moves nothing…” concluding that for Aristotle “desire or passion” is the primary motivating force in human action.[66]  Identifying desire with the passions, Arnhart asserts, “Aristotle recognizes—but does not elaborate—the psychological basis of ethics in the moral passions that is elaborated by David Hume and other philosophers like Adam Smith who argued for the existence of a moral sense.”[67] 

From the point of view of Darwinian natural right, a key aspect of Aristotle’s recognition of the moral sense is reflected in his attribution of human beings’ naturally social and political behavior to the natural inclination to care for one’s offspring, a point of view which is also shared by Hume.[68]  Arnhart recognizes that it is difficult to extend this natural sentiment to a generalized theory of justice, because human cooperative tendencies are matched by competitive ones that tend to restrict our concern to those proximate to us.  Nevertheless, he suggests that Hume and Aristotle would agree that this concern can “extend in principle to all members of the human species.”[69]

The real enemy of ethical naturalism according to Arnhart is not Hume, but Kant.  Kant rejected the idea that we can infer moral judgments from facts about human nature, since such natural facts pertain to the phenomenal realm, which is wholly determined by the laws of classical dynamics.[70]  Moral behavior for Kant must originate within the noumenal realm of an agent’s free choices.  Arnhart maintains that Kant accepted Hobbes’ unfortunate conclusion that human sociality is essentially an overcoming of our natural tendencies towards selfishness.[71] 

The contrast between Hume and Kant is significant for Arnhart, precisely because he thinks that the same sort of struggle with similar divisions has taken place among Darwinian treatments of ethical and political theory.  Darwin himself, according to Arnhart, embraced Humean/Aristotelian ethical naturalism in the Descent of Man. (74) Darwin attributes the development of morality to the gradual refinement and enlarging of the natural human tendency to care for one’s offspring.  This ground of human sociality is explained by the theory of evolution as an adaptive advantage for sophisticated organisms like human beings, who need long term care from childhood through early adulthood. (75)  Darwinian naturalism must respond to two significant objections: first that competitive tendencies among human groups militate against the extension of cooperation to a generalized theory of justice, and second that actions for the sake of others, like courage in battle, appear to contradict natural selection’s tendency to favor self-preservation.[72]  Arnhart points out that Darwin can respond to the first objection in the same way that Hume does, and to the latter objection Darwin argues that other regarding actions provide a reproductive advantage from the point of view of the social group although not the individual.[73] 

Evolutionary theorists following in Darwin’s footsteps appear to divide along the fault line of whether they accept his idea of group selection and his ethical naturalism.  Arnhart notes that Darwin’s close confidante Thomas Huxley eventually came to reject ethical naturalism and to hold the “Hobbesian-Kantian” position that nature is morally indifferent and that moral values cannot be derived from facts.[74]   While the latter position has been influential in evolutionary biology and political philosophy, Arnhart and some other political theorists have been working assiduously to rehabilitate Darwin’s Humean ethical naturalism.  Arnhart concludes, “…if we agree with Hume that moral obligation is grounded in natural human sentiments or desires, then we would have to say that human morality must be rooted in human nature.”[75]

In assessing the merits of Arnhart’s argument for Darwinian natural right theory as a potential alternative to natural law ethics, we must first ask whether it is necessary to embrace the conclusion that moral obligation, even for an ethical naturalist, is grounded only in human sentiments.  Arnhart’s enumeration of the similarities between Aristotle and Hume is surely correct in numerous respects.  Aristotle holds that practical judgment depends upon reason and desire, as opposed to reason alone, but we must wonder whether Arnhart fails to appreciate fully the nature of Aristotelian practical reason and the intrinsic value of the virtues and basic goods.  Even more fundamentally, it would appear problematic to equate desire with the passions for Aristotle, since that is to beg the question of whether we should exclude the rationality of desire in Aristotle’s analysis. 

Terence Irwin has argued forcefully that despite the overt similarities in language between Hume’s Treatise and Aristotle’s discussion of practical judgment in Nicomachean Ethics VI.1 and De Anima III.10, we should not equate the Aristotelian view of practical judgment with Humean sentimentalism.[76]  This view is consistent with medieval Aristotelians, such as Aquinas, who held that there are different forms of appetitive tendency, including rational appetite or will.  The very texts that Arnhart uses to establish Aristotle as a Humean sentimentalist lend support to the view that Aristotle’s conception of desire includes in some cases an intrinsic rational component. 

        Consider De Anima III.10, for instance.  In the passage where Aristotle argues that intellect does not move without desire, he adds that the object of desire is the good.[77]  Contrary to Hume and also to Hobbes as we have previously indicated, who hold that human beings share only common sentiments, Aristotle’s point here seems to be that human beings are naturally motivated by shared common possibilities for human fulfillment.  In the opening to the Nicomachean Ethics, for example, Aristotle argues that the evaluation of these goods requires a teleological account of the overall human good or happiness.  Arnhart stresses Aristotle’s treatment of certain passions as morally praiseworthy, despite the fact that they are distinct from the virtues, because they are dispositionally ordered to the virtues.[78]  He is admittedly correct, but it should also be noted that Aristotle treats the possession of the virtues as a cognitive dispositional state.  There is a difference, he insists, between a person who simply repeats the acts of the virtues, and one who does them from the state of possessing the particular virtue.  Acting from the state of possessing a virtue requires that the agent acts intentionally for the sake of the intrinsic good the virtue instantiates.[79] 

Another puzzle in Arnhart’s presentation is what to do with agents whose sentiments are conflicted, either because they are at odds with the species-typical norm, or because they are experiencing mutually incompatible desires.[80]  If the good is simply what is desired, rather than what is objectively desirable, it is difficult to say from what vantage point, other than an overall conception of the good, the value of various desires may be assessed.  Because they are different, we may be compelled to treat cultural psychopaths as abnormal, but we lack the rational basis for a critique of such behavior if morality is ultimately rooted in non-rational sentiments that cannot be further analyzed as goods.  In addition, Aristotle clearly thought that young people have natural tendencies that must be modified or shaped through the process of habituation.  Basic human desires for certain pleasures and against certain pains, for instance, must be shaped by moderation in order to possess the virtues of temperance and fortitude.  As we have argued above, Aquinas holds that the normative force of the natural inclinations to various goods must be integrated through the consideration of reason.  Humean sentimentalism does not provide for this possibility. 

Several other similar difficulties merit attention.  Arnhart acknowledges that human competitive inclinations tend to confine justice within the bounds of one’s particular social group.  Thus, he notes, “…the humanitarianism of human beings will always be difficult to cultivate and almost always weaker than their egoism, their nepotism, and their patriotism.[81]  Still, he thinks that Darwinian natural right can “constitute the universal principle of morality” through the broadening of human sentiments.[82]  He even goes so far as to suggest that this natural sentiment of justice can include recognition of the immorality of slavery.[83]  It is frankly quite hard to imagine how Darwinian ethical naturalism can produce anything like an Aristotelian theory of justice without treating reasons as fundamental norms.  Furthermore, the specific case of slavery seems particularly difficult.  Although we can imagine the broadening of human cooperative sentiments to include a city, state or even a large modern society, so long as we regard human cooperative and competitive tendencies as equally natural, there is always some competitive advantage to subordinating a particular group.  Nor can it be argued that such competitive advantage should be rejected upon the basis that all human beings are equally human, unless we are prepared to apply a universal rational standard of evaluation to a primitive moral sentiment.

A further difficult puzzle arising from the equation of the good with natural sentiments is the problem of critiquing the technological separation of the satisfaction of desires from their ordinary natural consequences.  Francis Fukuyama’s disturbing vision of a post-human future provides for the possibility of a world in which we may separate completely the satisfaction of some desires from their ordinary consequences.  It is possible to envision any number of examples in which science and technology may allow us to separate natural sentiment from what has traditionally been understood as human flourishing, for example.  Unless the normative force of our natural sentiments can be further analyzed in terms of their contributions to an overall conception of the human good, the content of morality would have very little stability, and our confident determination of normality vs. psychopathic behavior would collapse.

The final and perhaps the most fundamental difficulty with Arnhart’s account of Darwinian ethical naturalism based upon Humean sensibility theory lies in his conception of intersubjective objectivity.  Arnhart borrows Hume’s analogy between moral evaluations and secondary quality perception.  According to Hume, unlike primary qualities such as solidity, secondary qualities such as color are not extra-mental.  They are merely the propensity of a particular object to produce in the mind a perceptual response.  Just like color perception, Hume and Arnhart argue, moral evaluations are ‘true’ if the conduct that produces them is such as to induce a species-typical particular moral sentiment.  The normative force of a particular evaluation is nothing more than the fact of a species-typical sentimental response.  John McDowell offers a penetrating critique of this aspect of Humean theory from an Aristotelian perspective in his article, “Values and Secondary Qualities.”[84]  He insists that there is an important disanalogy between values and secondary quality perception: “The disanalogy, now, is that a virtue (say) is conceived to be not merely such as to elicit the appropriate ‘attitude’ (as a colour is merely such as to cause the appropriate experiences), but rather such as to merit it.”[85]  In order to illustrate the concept of ‘meriting’ a particular evaluation McDowell uses the evaluative concept ‘danger’, which he suggests is similar to a moral evaluation.  Any theoretical attempt to give an account of the correct application of the concept ‘danger’ must include not only the fact that a particular object induces the perception of danger, but that such an object is in fact dangerous, or such as to merit the application of the concept.[86]  McDowell’s purpose is to argue against the unreality of values presumed by Humean non-cognitivism.  But, it also shows why, from the point of view Aristotelian ethical naturalism, it is not sufficient to reduce moral norms to species-typical moral sentiments or natural inclinations themselves.  Natural inclinations are not normative because of the bare fact of their existence, but because they are natural human tendencies toward human perfection understood in the context of the overall human good.

Neo-Darwinian Naturalism, Political Theory and the Transcendent

That is why religious nations have often accomplished such lasting achievements.  For in thinking of the other world, they had found out the great secret of success in this.  Religions instill a general habit of behaving with the future in view…  But as the light of faith grows dim, man’s range of vision grows more circumscribed, and it would seem as if the object of human endeavors came daily closer.[87]

Up to this point we have considered some internal difficulties with Darwinian natural right as a replacement for traditional ethical naturalism.  Alexis de Tocqueville reminds us of an external difficulty.  The purpose here is not to critique evolutionary theory as such, but to ask whether Darwinian natural right can provide a fully adequate moral and political philosophy from its own resources.  The problem with such ‘materialist’ views according to Tocqueville is that they end up with an impoverished conception of the human person and social life that cannot preserve human dignity against the degrading tendencies inherent within a liberal democracy.  In this respect, they share some of the problems faced by those who completely reject the ethical implications of human nature.

Although Darwinian natural right theorists wish to preserve the dependence of ethical and political principles upon human nature, like other modern moral philosophers their conception of nature is fairly thin because it is largely empirical and physicalistic.  In a recent critique of Darwinian natural right theory, Carson Holloway argues that this approach to ethical naturalism ultimately fails because it preserves a “merely decent” conception of society, instead of fostering human excellence.[88]  He calls upon Alexis de Tocqueville’s assertion that a democracy which fails to temper the mediocre and hedonistic temptations of its citizens with a yearning for higher goods, is likely to end up with oppression through the “tyranny of the majority” and the dehumanizing effects of mass society.[89]  Tocqueville pointed out that Christianity, with its twofold emphasis upon the dignity of the individual person and the individual’s simultaneous transcendent calling has been the salvation of the American democratic system.  Without this elevating and transcendent aspect Tocqueville suggests that American democracy would have succumbed to the worst tendencies of hedonistic self-interest.  But he does not stop there.  Transcendent religious aspirations are, he insists, a part of human nature: 

It is by a sort of intellectual aberration, and in a way, by doing moral violence to their own nature, that men detach themselves from religious beliefs; an invincible inclination draws them back.  Incredulity is an accident; faith is the only permanent state of mankind.  Considering religions from a purely human point of view, one can then say that all religions derive an element of strength which will never fail from man himself, because it is attached to one of the constituent principles of human nature.”[90]

Oddly enough, when we place Tocqueville’s assertion into the context of a traditional version of natural law ethics such as that of Aquinas we are faced with an apparent paradox in the form of the distinction between the natural and supernatural ends of human persons.  Perhaps Tocqueville’s argument would render Thomistic natural law theory moot as well, since it regards supernatural beatitude as beyond unaided human nature?  This paradox is only apparent, however, because Aquinas asserts, as did Augustine before him, that the human tendency towards a perfect transcendent good is natural.  Furthermore, he places the virtue of religion under the heading of the moral virtue justice, distinguishing it explicitly from the theological virtues: faith, hope and charity.[91]    Although Aquinas speaks of two kinds of beatitude, he does not assert that the human person has two ultimate ends, even though he does speak of a kind of natural happiness proportioned to the immanent capacities of human nature.[92]    From the point of view of the human subject, happiness is something natural because it is an activity of the soul according to the highest virtue. [93]  From the point of view of the object, perfect happiness is something beyond the immanent capacities of human nature, though not contrary to them.  In this sense, imperfect and perfect beatitude are both genuinely natural ends of human activity.  To speak of religion and a supernatural end is not therefore to place oneself automatically outside the consideration of nature.  We do not need to deny that there is a natural end of human life, proportioned to immanent human capacities in order to agree with Tocqueville that human beings have a natural desire for supernatural happiness.[94] 

Tocqueville’s observations suggest a somewhat curious but very important result.  They imply openness in human nature to multiple possibilities in the specification of the ultimate end.  This is true whether or not we concede that human beings actually have a transcendent ultimate end.  True or false as a view about human life, it is a possibility that must be considered.  Granting the possibility of a transcendent end, which would entail the fact that human beings are ordered to an end they can desire but not achieve by virtue of their own immanent functional capacities, the relationship of human nature to the human good turns out to be complex.  It is not merely deducible from a thin empirical analysis of those functional capacities themselves.  Our grasp of human natural inclinations can only be made sense of in light of reflection upon human possibilities for fulfillment.  Thus, the normative character of the natural inclinations cannot be defended apart from a genuine theory of practical reason, in which goods provide the rational basis for appetitive tendencies.  This conclusion is consistent with the analysis of Aquinas’ account of practical reasoning above, and it militates against the acceptance of Arnhart’s Humean sentimentalism.

Perhaps the most challenging aspect of Tocqueville’s argument against what he calls ‘materialist’ theories is that by trying to reduce the good to an enumeration of strictly immanent human functional capacities, they vitiate the very attainment of the political goods they seek to preserve in liberal democracies.  A purely mundane vision of the human person, according to Tocqueville, will destroy the pursuit of human excellence and will grant unbridled freedom to the inherent democratic tendency towards self-centered hedonism.  A chilling empirical confirmation of Tocqueville’s assertion may be on the horizon in the form of the coming biotechnological revolution, in which human beings may finally be able to alter human nature in order to satisfy their desires.  What matters to the human organism from an evolutionary point of view is reproductive success for oneself or one’s proximate genetic relatives, not the abstract good of a whole race, or even the species.  As Carson Holloway argues in his critique of Darwinian natural right, this invites the dehumanization of our nature through advances in various eugenic programs.[95]  Neo-Darwinians who argue to the contrary that there is a basis in evolutionary naturalism for an argument favoring individual human dignity engage in a non-sequitur.  Since there are no species-transcendent moral values, there is no basis for one species or the evolved state of a species to be preferred to another.  Based upon Darwinian premises alone, we have many reasons to wish that the nature of our offspring and the future state of the human community be very different from its present condition.  None of this is incompatible with the fundamental genetic desire for self-preservation.  In the final analysis, the attempt to derive a full-scale conception of morality strictly from the observation of human sentiments and immanent capacities is deeply flawed.


My point is that those who stand outside all judgements of value cannot have any ground for preferring one of their own impulses to another except the emotional strength of that impulse…  At the moment, then, of Man’s victory over Nature, we find the whole human race subjected to some individual men, and those individuals subjected to that in themselves which is purely ‘natural’—to their irrational impulses. Nature, untrammelled by values, rules the Conditioners and, through them, all humanity. Man’s conquest of Nature turns out, in the moment of its consummation, to be Nature’s conquest of Man. [96]

As early as 1944, in the Abolition of Man C.S. Lewis warned of the grim possibility of a post-human future brought on by the biotechnological revolution that is currently gaining momentum all around us.  Lewis stressed that he was not a Luddite who opposed either developments in science or advances in technology as such.  But, he was concerned about certain dangers inherent in Descartes and Bacon’s project of making human beings masters and possessors of nature.  The unfolding of this project had at least two important intellectual effects.  First, human beings came to think of themselves as reversing their relationship to nature.  Instead of needing to conform to nature in order to succeed, now they could refashion nature in their own image according to their desires.  Second, mastery was achieved through the quantification of nature.  The old qualitative and teleological systems of natural philosophy were set aside in favor of new empirical and rational approaches. 

Both of these developments have had profound ethical implications.  We have documented how the replacement of the classical conception of nature with the modern one has led to a qualitatively thin empirical account of human life.  Lewis suggested that a general effect of the new quantitative approach was to produce a value neutral understanding of anything assigned to the category of ‘nature’ as a mere artifact.  What the biotech revolution makes possible is that human life itself shall be rendered a mere ‘natural object’ open to technological manipulation.  Furthermore, it is a consequence of the modern view that no inherent values can guide or limit this technological manipulation, since we have overcome nature’s limits and our understanding of a ‘natural object’ is value neutral in any case.  Lewis’ worry was that only the pleasures and sentiments of those who would be in control of the process would be left to guide the biotech revolution.  Paradoxically, the human victory of mastery over nature would end up subordinating most human beings to the crudest ‘natural’ sentiments of a small minority of other human beings.  Recent history has demonstrated that Lewis’ concerns were well founded, since our contemporaries disagree not only over what biotechnological manipulations we ought to undertake, but also whether any ethical imperatives whatsoever should intrude upon scientific and technological progress.

This shows that there is a simple, if somewhat flippant, answer to the concern that we may not be able to get back to nature in the contemporary world because the old idea that human nature has ethical implications has been outmoded.  We may disagree about what those ethical implications are, but we cannot escape them.  None of this comes as a surprise to natural law theorists.  Claiming that ‘human nature’ just is a term for a certain natural artifact for which an empirical/factual, but not a qualitative/ teleological description can be given has important moral and political consequences.  We must evaluate those consequences in light of whether they constitute the best possibility for human fulfillment.  This requires an understanding of human nature in light of an overall conception of the good life.  We cannot escape the need for this kind of inquiry.  Such an evaluation is not in principle anti-scientific or anti-technological, even if it challenges the view that a deeper qualitative understanding of human nature is either unachievable or unscientific.

For this reason, there is a danger of failing to recognize the good in the Darwinian natural right theory even as we critique it.  The effort to discover the ethical implications of nature in light of advances in the natural sciences ought to be applauded as a positive development.  Darwinian natural right theorists astutely criticize positivistic accounts that treat ethical appeals to nature as simply meaningless because of a putative logical gulf between facts and values.  As we have seen with regard to Aquinas’ treatment of the first principles of the natural law, getting beyond such a simplistic view of meaning does not entail the conclusion that ethics can merely be deduced from a set of naturalistic descriptions in physics or metaphysics.  There is truth in the fact/value distinction when it is properly understood.  Evolutionary naturalists like Larry Arnhart ought be applauded and studied carefully for their efforts to restore a basically Aristotelian account of the virtues and human excellence, and to defend human dignity, from within the limits of a scientific point of view.  There is much to be gained from Arnhart’s evolutionary critique of Hobbesian egoism and utopian social constructionism, which tends to treat nature as a kind of infinitely malleable artifact for social engineering.  Evolutionary naturalists have also made significant strides toward showing that teleological descriptions have a place in natural science, although we ought to challenge the idea that immanent and cosmic teleological reasoning are fundamentally incompatible. 

These strengths in Darwinian natural right theories are matched by important weaknesses.  Arnhart’s appeal to Humean sentimentalism based upon the analogy between value and secondary quality perception can find no deeper basis for the normative significance of nature than species-typical sentiments themselves.  But, as John McDowell has pointed out, there is an important disanalogy between practical judgment and secondary quality perception.  It is not merely the empirical fact that we have certain species-typical responses that make them normative, but that our responses are merited by our nature and the way things are.  After all, as Aquinas recognized, there can be fundamental conflicts between natural human sentiments.  Through habituation to the virtues our natural responses must be shaped and corrected by practical judgment about the human good.  Natural inclinations are normative within a practical grasp of our nature and possibilities for human fulfillment.  In other words, a genuine theory of practical reason is needed.  Sentimentalism is not enough.  C.S. Lewis pointed to the fundamental problem with this approach in The Abolition of Man.  It provides no vantage point from which to criticize the final conquest of nature, which will result not in liberation, but our subordination to the passions of a small minority in power.  As Alexis de Tocqueville recognized, only a qualitatively deeper and ultimately transcendent understanding of the meaning and purpose of human life can in the final analysis sustain the liberties we have worked so hard to achieve through liberal democracy and the quest for advances in human understanding through the mastery of nature.  Natural law arguments in ethics and politics should therefore remain a vital and important source of reflection about the human good.



Assumption College

Worcester, Massachusetts

About the Author

Works Cited:

Aristotle, and Terence Irwin. Nicomachean Ethics. 2nd ed. Indianapolis, Ind.: Hackett Pub. Co., 1999.

Arnhart, Larry. Darwinian Natural Right : The Biological Ethics of Human Nature, Suny Series in Philosophy and Biology. Albany, NY: State University of New York Press, 1998.

———. "The New Darwinian Naturalism in Political Theory." The American Political Science Review 89, no. 2 (1995): 389-400. Available from

———. "Stealing Darwin." National Review 53, no. 6 (April 02, 2001): 46-48. Available from

Brague, Rémi. The Wisdom of the World : The Human Experience of the Universe in Western Thought. Chicago, Ill.: University of Chicago Press, 2003.

Brink, David Owen. Moral Realism and the Foundations of Ethics, Cambridge Studies in Philosophy. Cambridge ; New York: Cambridge University Press, 1989.

Descartes, René. Discourse on Method for Reasoning Well and for Seeking Truth in the Sciences in, 2006 [cited 2007-04-26 16:34:34 2007]. Available from

Finnis, John. Natural Law and Natural Rights. Oxford: Clarendon Press, 1980.

Flannery, Kevin L. Acts Amid Precepts : The Aristotelian Logical Structure of Thomas Aquinas's Moral Theory. Washington, D.C.: Catholic University of America Press, 2001.

Fukuyama, Francis. Our Posthuman Future : Consequences of the Biotechnology Revolution. 1st ed. New York: Farrar, Straus and Giroux, 2002.

Hobbes, Thomas. Leviathan in University of Adelaide Library, 2007 [cited April 23 2007]. Available from

Holloway, Carson. The Right Darwin? : Evolution, Religion, and the Future of Democracy. Dallas, Tex.: Spence Pub. Co., 2006.

Hume, David, L. A. Selby-Bigge, and P. H. Nidditch. A Treatise of Human Nature. 2d ed. Oxford: Clarendon Press (Oxford), 1978.

Irwin, T. H. "Aristotle on Reason, Desire, and Virtue." The Journal of Philosophy 72, no. 17 (October 1975): 567-78. Available from

Kant, Immanuel. Fundamental Principles of the Metaphysic of Morals in University of Adelaide Library, 2004 [cited 04-23 2007]. Available from

Lewis, C.S. The Abolition of Man. New York: Touchstone Books, 1996.

MacIntyre, Alasdair C. After Virtue : A Study in Moral Theory. 2nd ed. Notre Dame, Ind.: University of Notre Dame Press, 1984.

Maritain, Jacques. The Range of Reason in University of Notre Dame, (1952) [cited 2007-04-24 23:59:50 2007]. Available from

Matar, Anat Biletzki and Anat. Ludwig Wittgenstein in The Stanford Encyclopedia of Philosophy. Winter 2006. Available from

McDowell, John. "Values and Secondary Qualities." In Essays on Moral Realism, edited by Geoffrey Sayre-McCord. Ithaca NY: Cornell University Press, 1988.

———. "Virtue and Reason." In Virtue Ethics, edited by Roger Crisp and Michael Slote. New York: Oxford University Press, 1997.

Mill, John Stuart. Utilitarianism in University of Adelaide Library, 1998 [cited 04-23 2007]. Available from

Nelson, Daniel Mark. The Priority of Prudence : Virtue and Natural Law in Thomas Aquinas and the Implications for Modern Ethics. University Park, Pa.: Pennsylvania State University Press, 1992.

Schapiro, Meyer. ""Muscipula Diaboli," the Symbolism of the Merode Altarpiece." The Art Bulletin 27, no. 3 (September 1945): 182-87. Available from

Staley, Kevin. "Happiness: The Natural End of Man." The Thomist 53 (April 1989): 215-34.

Stephen Darwall, Allan Gibbard, Peter Railton. "Toward Fin De Siecle Ethics: Some Trends." The Philosophical Review 101, no. 1 (January 1992): 115-89. Available from

Tocqueville, Alexis de, and J. P. Mayer. Democracy in America. 1st Perennial library ed: Harper & Row, 1988.

Wiggins, David. Ethics : Twelve Lectures on the Philosophy of Morality. Cambridge, Mass.: Harvard University Press, 2006.


List of Illustrations

Page 11

Plate 7: The Unicorn in Captivity, South Netherlands, 1495–1505  (Metropolitan Museum of Art).
Photograph from  in the public domain.


Page 12

Plate 2: The Unicorn Leaps across a Stream, South Netherlands, 1495–1505  (Metropolitan Museum of Art).
Photograph from . Used by permission: .

Page 14

Plate 8: The Annunciation Triptych, Netherlands, ca. 1425, Robert Campin. (Metropolitan Museum of Art).

Photograph from Used by permission: .

Plate 9: The Annunciation Triptych (detail).
Photograph from  in the public domain.

Page 17

Plate 10: Henri Gervex , Before the Operation, 1887 (Musée d’Orsay).
Photograph by Gavin Colvert.

Page 19

Plate 11: Claude Monet, The Argenteuil Bridge, 1874 (Musée d’Orsay).

Photograph by Gavin Colvert.


[1] Benedict XVI, Address to the Participants in the International Congress on Natural Law, Vatican City, February 12, 2007.  <URL:>.  See also, Benedict XVI, Meeting with the Representatives of Science, Lecture of the Holy Father, Regensburg, Germany, September 12, 2006, <URL:> .

[2] A portion of this paper was presented at St. Anselm College in November 2006.  I wish to thank the College for the generous invitation to give this lecture.

[3] Francis Fukuyama, Our Posthuman Future : Consequences of the Biotechnology Revolution, 1st ed. (New York: Farrar, Straus and Giroux, 2002).

[4] See, for example, Larry Arnhart, Darwinian Natural Right : The Biological Ethics of Human Nature, Suny Series in Philosophy and Biology (Albany, NY: State University of New York Press, 1998).

[5] Jacques Maritain, The Range of Reason, in (University of Notre Dame, (1952) [cited 2007-04-24 23:59:50 2007]); available from

[6]René Descartes, Discourse on Method for Reasoning Well and for Seeking Truth in the Sciences, in (2006 [cited 2007-04-26 16:34:34 2007]); available from  “For my notions had made me see that it is possible to reach understandings which are extremely useful for life, and that instead of the speculative philosophy which is taught in the schools, we can find a practical philosophy by which, through understanding the force and actions of fire, air, stars, heavens, and all the other bodies which surround us as distinctly as we understand the various crafts of our artisans, we could use them in the same way for all applications for which they are appropriate and thus make ourselves, as it were, the masters and possessors of nature.”

[7] Rémi Brague, The Wisdom of the World : The Human Experience of the Universe in Western Thought (Chicago, Ill.: University of Chicago Press, 2003).

[8] Brague, p. 185.

[9] See Brague, p. 194.

[10] J.S. Mill, Nature, in Brague, p. 203.

[11] See Brague, p. 209. “But the good comes back to nature: since good is not in nature, it is thus necessary to introduce it into nature.  And by force, by taking nature against the grain…  Modern technology defines itself through an undertaking of domination, through a plan to become, according to the famous epigram of Descartes, the “master and possessor of nature.”

[12] See Nicomachean Ethics, I.1-2 (1094a1-25), also I.7 (1097a15-8a15).

[13] See Politics, I.2 (1253a1-25).

[14] It is beyond the scope of the present analysis to give full consideration to the debate concerning the distinction between natural and supernatural beatitude in the tradition.  For Aquinas’ treatment of this subject see Summa theologiae (hereafter ST) I-II.3.8, and also I-II.5.1 & 5.  Aquinas argues that although human beings cannot attain perfect beatitude without divine assistance, human nature is more perfect than  some other creatures because human beings are capable of attaining such perfection with divine assistance.

[15] Thomas Hobbes, Leviathan, in (University of Adelaide Library, 2007 [cited April 23 2007]); available from Introduction: “NATURE (the art whereby God hath made and governs the world) is by the art of man, as in many other things, so in this also imitated, that it can make an artificial animal…  Art goes yet further, imitating that rational and most excellent work of Nature, man. For by art is created that great LEVIATHAN called a COMMONWEALTH, or STATE (in Latin, CIVITAS), which is but an artificial man…the pacts and covenants, by which the parts of this body politic were at first made, set together, and united, resemble that fiat, or the Let us make man, pronounced by God in the Creation.  To describe the nature of this artificial man, I will consider First, the matter thereof, and the artificer; both which is man.”

[16] Hobbes, Leviathan, Introduction.

[17] John Stuart Mill, Utilitarianism, in (University of Adelaide Library, 1998 [cited 04-23 2007]); available from Chapter 2: “It is quite compatible with the principle of utility to recognise the fact, that some kinds of pleasure are more desirable and more valuable than others. It would be absurd that while, in estimating all other things, quality is considered as well as quantity, the estimation of pleasures should be supposed to depend on quantity alone.”

[18] Mill, Utilitarianism, Chapter 2. “If I am asked, what I mean by difference of quality in pleasures, or what makes one pleasure more valuable than another, merely as a pleasure, except its being greater in amount, there is but one possible answer. Of two pleasures, if there be one to which all or almost all who have experience of both give a decided preference, irrespective of any feeling of moral obligation to prefer it, that is the more desirable pleasure.”

[19] Immanuel Kant, Fundamental Principles of the Metaphysic of Morals, in (University of Adelaide Library, 2004 [cited 04-23 2007]); available from Preface: “Material philosophy, however, [which] has to do with determinate objects and the laws to which they are subject, is again twofold; for these laws are either laws of nature or of freedom. The science of the former is physics, that of the latter, ethics… Natural and moral philosophy…can each have their empirical part, since the former has to determine the laws of nature as an object of experience; the latter the laws of the human will, so far as it is affected by nature…We may call all philosophy empirical, so far as it is based on grounds of experience: on the other band, that which delivers its doctrines from a priori principles alone we may call pure philosophy…In this way there arises the idea of a twofold metaphysic — a metaphysic of nature and a metaphysic of morals.  Physics will thus have an empirical and also a rational part. It is the same with Ethics…”

[20] Kant, Fundamental Principles, Section 1. “…a man cannot form any definite and certain conception of the sum of satisfaction of all [desires]…which is called happiness… Thus the moral worth of an action does not lie in the effect expected from it, nor in any principle of action which requires to borrow its motive from this expected effect. For all these effects, agreeableness of one's condition and even the promotion of the happiness of others — could have been also brought about by other causes, so that for this there would have been no need of the will of a rational being; whereas it is in this alone that the supreme and unconditional good can be found. The pre-eminent good which we call moral can therefore consist in nothing else than the conception of law in itself, which certainly is only possible in a rational being, in so far as this conception, and not the expected effect, determines the will.”

[21] Alasdair C. MacIntyre, After Virtue : A Study in Moral Theory, 2nd ed. (Notre Dame, Ind.: University of Notre Dame Press, 1984). pp. 43-46, 52.

[22] Aristotle, Physics II.2 (194a20-25).

[23] For a brief description of the Unicorn tapestries see the Metropolitan Museum’s online catalogue: .

[24] For a brief description of this painting see the Metropolitan Museum’s online catalogue:  See also the following source, upon which the present discussion of the iconography of the painting draws: Meyer Schapiro, ""Muscipula Diaboli," the Symbolism of the Merode Altarpiece," The Art Bulletin 27, no. 3 (September 1945); available from

[25] A copy of the relevant passage from the sermons (see sermon CXXX section 2) is available at:

[26] See e.g. Brague, p. 190.

[27] One exception to this trend within the various Realist schools that appears to demonstrate the norm is the case of the Pre-Raphaelite Brotherhood in England.  This group of artists combined an interest in naturalism and realistic representation with a deliberate attempt to incorporate and recover elements from late medieval northern European artwork.  For a brief discussion of this movement see:

[28] For a brief description of the painting, from which some of the details discussed here are drawn see the catalogue of the Musée d’Orsay at:

[29] For this quotation see the catalogue description of Haystacks from the  National Gallery of Australia, (Quoted in translation from W.G.C. Byvanck, Un Hollandais à Paris en 1891, Paris, 1892, p. 176.)

[30] See Mill, Utilitarianism, Ch 1: “The difficulty is not avoided by having recourse to the popular theory of a natural faculty, a sense or instinct, informing us of right and wrong. For- besides that the existence of such- a moral instinct is itself one of the matters in dispute- those believers in it who have any pretensions to philosophy, have been obliged to abandon the idea that it discerns what is right or wrong in the particular case in hand, as our other senses discern the sight or sound actually present. Our moral faculty, according to all those of its interpreters who are entitled to the name of thinkers, supplies us only with the general principles of moral judgments; it is a branch of our reason, not of our sensitive faculty; and must be looked to for the abstract doctrines of morality, not for perception of it in the concrete. The intuitive, no less than what may be termed the inductive, school of ethics, insists on the necessity of general laws. They both agree that the morality of an individual action is not a question of direct perception, but of the application of a law to an individual case.”

[31] See Kant, Fundamental Principles, First Section.

[32] For a discussion of Wittgenstein on rule following see: Anat Biletzki and Anat Matar, Ludwig Wittgenstein, in The Stanford Encyclopedia of Philosophy, (Winter 2006 [cited); available from

[33] See John McDowell, "Virtue and Reason," in Virtue Ethics, ed. Roger Crisp and Michael Slote (New York: Oxford University Press, 1997), 142. “The deliverances of a reliable sensitivity are cases of knowledge; and there are idioms according to which the sensitivity itself can appropriately be described as knowledge: a kind person knows what it is like to be confronted with a requirement of kindness.  The sensitivity is, we might say, a sort of perceptual capacity.”  See also John McDowell, "Values and Secondary Qualities," in Essays on Moral Realism, ed. Geoffrey Sayre-McCord (Ithaca NY: Cornell University Press, 1988), 166-80.  McDowell unfortunately argues for a version of moral particularism in which all ethical judgments are deliverances of cognitive sensibilities and none can be derived from more general ethical principles.  It is beyond the scope of the present analysis to refute this claim.  We must simply note that Aquinas’ moral philosophy envisions both cognitive but non-algorithmic prudential judgments and moral conclusions derived from or justified by appeals to general principles such as those of the natural law.

[34] David Wiggins, Ethics : Twelve Lectures on the Philosophy of Morality (Cambridge, Mass.: Harvard University Press, 2006), 173.

[35] Ibid., 174.

[36] See e.g. Daniel Mark Nelson, The Priority of Prudence : Virtue and Natural Law in Thomas Aquinas and the Implications for Modern Ethics (University Park, Pa.: Pennsylvania State University Press, 1992).

[37]David Hume, A Treatise of Human Nature, Second Edition, L.A. Selby-Bigge & P.H. Nidditch eds., Oxford: The Clarendon Press, 1978. Book III.i.1,  455-470.

[38]G.E. Moore, Principia Ethica, I.5-14, Amherst, NY: Prometheus Books, 1988, 5-21.

[39]This fact is pointed out by John Finnis. See: John Finnis, Natural Law and Natural Rights (Oxford: Clarendon Press, 1980), 37ff.  Unfortunately, in the same place Finnis appears to embrace the more sweeping view of a radical cleavage between fact and value.

[40] David Hume, A Treatise of Human Nature,  457.

[41]Ibid.,  457. also 458, 459, 462, 465, 466.

[42] See David Owen Brink, Moral Realism and the Foundations of Ethics, Cambridge Studies in Philosophy (Cambridge ; New York: Cambridge University Press, 1989), 153. See also Allan Gibbard Stephen Darwall, Peter Railton, "Toward Fin De Siecle Ethics: Some Trends," The Philosophical Review 101, no. 1 (January 1992): 116-17; available from

[43]See David Brink, Moral Realism and the Foundations of Ethics, 153.

[44] See Nicomachean Ethics I.7 (1097b25-1098a20).

[45] See ST I.5.1.

[46] For useful discussion of this points see Kevin L. Flannery, Acts Amid Precepts : The Aristotelian Logical Structure of Thomas Aquinas's Moral Theory (Washington, D.C.: Catholic University of America Press, 2001).

[47] See e.g., Arnhart, Darwinian Natural Right : The Biological Ethics of Human Nature, 262-66.

[48] For a useful discussion of this point see Flannery, Acts Amid Precepts : The Aristotelian Logical Structure of Thomas Aquinas's Moral Theory.

[49] See ST I-II.95.2c.

[50] Arnhart, Darwinian Natural Right : The Biological Ethics of Human Nature.

[51] Ibid., 4-5.

[52] Ibid., 1.

[53] Larry Arnhart, "Stealing Darwin.," National Review 53, no. 6 (April 02, 2001); available from

[54] Ibid.

[55] Ibid.

[56] Ibid., also Arnhart, Darwinian Natural Right : The Biological Ethics of Human Nature, 5.

[57] See Larry Arnhart, "The New Darwinian Naturalism in Political Theory," The American Political Science Review 89, no. 2 (1995): 389-400; available from, also Arnhart, Darwinian Natural Right : The Biological Ethics of Human Nature, 7-8, 69-81.

[58] Arnhart, Darwinian Natural Right : The Biological Ethics of Human Nature, 69.

[59] Arnhart credits this insight originally to Alasdair MacIntyre.  See: Ibid., 4.

[60] Ibid., 70.

[61] Ibid.

[62] David Hume, L. A. Selby-Bigge, and P. H. Nidditch, A Treatise of Human Nature, 2d ed. (Oxford: Clarendon Press (Oxford), 1978), 469.

[63] Arnhart, Darwinian Natural Right : The Biological Ethics of Human Nature, 70-71.

[64] Ibid., 71.

[65] Ibid.

[66] Ibid.  Arnhart’s quotation here is a bit odd, since he refers the reader to De Anima III.10 (433a10-31).  While that passage discusses the dependence of practical judgment upon desire, it would appear that the quotation is actually from a parallel passage at Nicomachean Ethics VI.1 (1139a35-b5), “Thought by itself moves nothing; what moves us is goal directed thought concerned with action.” (The translation is from: Aristotle and Terence Irwin, Nicomachean Ethics, 2nd ed. (Indianapolis, Ind.: Hackett Pub. Co., 1999).). It far from clear in either passage that Aristotle shares Hume’s non-cognitivist tendency to bifurcate reason and desire and to regard practical judgment as at base non-rational.  For corroboration of this doubt see T. H. Irwin, "Aristotle on Reason, Desire, and Virtue," The Journal of Philosophy 72, no. 17 (October 1975); available from

[67] Arnhart, Darwinian Natural Right : The Biological Ethics of Human Nature, 72.

[68] Ibid., 72-73.

[69] Ibid., 73.

[70] Ibid., 74.

[71] Ibid.

[72] Ibid., 75-76.

[73] Ibid., 76.

[74] Ibid., 77.

[75] Ibid., 80.

[76] See, Irwin, "Aristotle on Reason, Desire, and Virtue."

[77] See De Anima III.10 (433a20-30).

[78] Arnhart, Darwinian Natural Right : The Biological Ethics of Human Nature, 72.

[79] See Nicomachean Ethics II.4 (1105a30-35).

[80] For a discussion of psychopathic behavior and the natural moral sense, see Arnhart, Darwinian Natural Right : The Biological Ethics of Human Nature, Chapter 8, 211-30.

[81] Ibid., 73.

[82] Ibid.

[83] Arnhart, "The New Darwinian Naturalism in Political Theory," 391.

[84] McDowell, "Values and Secondary Qualities," 166-80.

[85] Ibid., 175.

[86] Ibid., 176.

[87] Alexis de Tocqueville and J. P. Mayer, Democracy in America, 1st Perennial library ed. (Harper & Row, 1988), 547.

[88] Carson Holloway, The Right Darwin? : Evolution, Religion, and the Future of Democracy (Dallas, Tex.: Spence Pub. Co., 2006).

[89] Ibid., 17-29. See also Tocqueville and Mayer, Democracy in America, 246-76.

[90] Tocqueville and Mayer, Democracy in America, 296-97.

[91] See ST II-II.81.5.

[92] For a useful discussion of this point see: Kevin Staley, "Happiness: The Natural End of Man," The Thomist 53 (April 1989): 215-34.  For the relevant passages in Aquinas see ST I-II.2, 3, 5.

[93] See ST I-II.3.1.

[94] Two points made by Arnhart with regard to this topic merit consideration, but are beyond the scope of the present analysis.  First, he draws a distinction between immanent and cosmological teleological descriptions.  He asserts that Aristotle’s use of biological teleology is immanent and excludes cosmological teleological explanations, such as that natural processes are rationally ordered by a divine mind.  He concludes that this is compatible with evolutionary theory, and that evolutionary theory necessarily excludes cosmic teleological explanations.  Furthermore, he suggests that many who appeal to the necessity of religion depend upon such cosmological explanations and the concept of a supernatural will.  See Arnhart, Darwinian Natural Right : The Biological Ethics of Human Nature, 238-49.  It should be clear from the present context that Aquinas’ ethical argumentation appeals to immanent teleology, but that such immanent teleology does not exclude complementary cosmic teleological explanations. 

[95] See Holloway, The Right Darwin? : Evolution, Religion, and the Future of Democracy, 148-77.

[96] C.S. Lewis, The Abolition of Man (New York: Touchstone Books, 1996), 76.