Monday, June 27, 2011

The Biology of Thomistic Natural Law: ST, I-II, q. 94, a. 2

At the convention of the American Political Science Association in Seattle, September 1-4, I will be presenting a paper entitled "Thomistic Natural Law as Darwinian Natural Right: Replies to Critics." I will be answering all of the various objections that have been offered to my claim that Thomas Aquinas's natural law can be understood as rooted in human biological nature.

The best statement of Thomas's natural law reasoning is in his "Treatise on Law" in the Summa Theologica (I-II, q. 90-114). Within that section of the book, the most notable passage is question 94, article 2: "Does the natural law contain several precepts or only one?" Here Thomas sketches the general precepts of natural law as organized in three levels.

In my paper, I will argue that the content and structure of these precepts manifest human biological nature as presented in the biological science of Aristotle and Albert the Great (Thomas's teacher and mentor). I will also argue that this biological understanding of natural law is compatible with Darwinian evolutionary biology.

Here's my translation of one passage from this part of the Summa:

. . . The precepts of the natural law in a human being are related to action as the first principles to matters of demonstration. But there are several indemonstrable first principles. Therefore, there are also several precepts of natural law.

. . . The precepts of the natural law are related to practical reason as the first principles of demonstration are related to speculative reason. For both are self-evident principles. . . .

Now, there is a certain order to be found in the things that fall under human apprehension. For what first falls within our apprehension is being, the understanding of which is included in everything that one understands. And so the first indemonstrable principle is that the same thing cannot be affirmed and denied at the same time, which is based on the nature of being and nonbeing, and all other principles are based on it, as the METAPHYSICS says. And as being is the first thing that without qualification falls within apprehension, so good is the first thing that falls within the apprehension of practical reason. And practical reason is ordered to action, since every agent acts for the sake of an end under the meaning of good. Consequently, the first principle in the practical reason is one founded on the meaning of good, namely, that good is what all things seek. Therefore, the first precept of the natural law is that we should do and seek good, and shun evil. And all the other precepts of the natural law are based upon this, so that whatever the practical reason naturally apprehends as human goods or evils belong to the precepts of the natural law as things to be done or shunned.

And since good has the meaning of an end, and evil the meaning of the contrary, hence it is that all those things to which human beings have a natural inclination are naturally apprehended by reason as being good and, consequently, as objects of pursuit, and their contraries as evil and objects of avoidance. Therefore, the order of the natural inclinations is the order is the order of the precepts of the natural law.

Because there is first in a human being an inclination to good in accordance with the nature which he has in common with all substances, inasmuch as every substance seeks the preservation of its own existence according to its nature. And according to this inclination, whatever is a means of preserving human life and preventing the the contrary belongs to the natural law.

Secondly, there is in a human being an inclination to things that pertain to him more specially according to that nature that he has in common with other animals, and accordingly, those things are said to belong to natural law "that nature has taught all animals," such as the intercourse of male and female, the education of children, and so forth.

Thirdly, there is in a human being and inclination to good according to the nature of reason, which is proper to him; thus a human being has a natural inclination to know the truth about God and to live in society. And so whatever pertains to this inclination belongs to the natural law, for instance, to shun ignorance, to avoid offending those among whom one has to live, and other such things regarding this inclination.

Thomas has said that while being and goodness are the same, they differ in that goodness appears under the aspect of desirableness, because the good is the desirable (I, q 5, a 1). Being and goodness are the same, because the good is that by which something becomes what it is by developing its potentiality to actuality, which is its perfection. Every living being has some tendency or inclination; it aims at an end or goal. The good of each living being is its self-fulfillment.

The growth of an acorn into an oak tree or a puppy into a dog illustrates this. It is good for a plant or animal to grow to maturity. It is bad for its growth to be impeded by unfavorable circumstances. Thus, we recognize a puppy to be defective if it cannot develop fully the potentialities of its species. Goodness is not some external standard imposed on things from the outside; it is rather the unfolding of the innate tendencies of things. It is therefore self-evident that the good is to be sought, because by definition the good is what each thing seeks. To say that all things should seek the good is simply to endorse what all things strive to do anyway.

While speculative reasoning apprehends the being of things, practical reasoning apprehends the being of things under the appearance of their desirability or undesirability. Thus, practical reasoning is not a matter of pure logic, because it requires a combination of the rational and the inclinational, so that things are apprehended practically in relationship to one's desires as either facilitating or impeding one's inclinations. Consequently, all those things to which we have a natural inclination are apprehended by reason as being good. The order of our natural inclinations then set the order of the precepts of the natural law.

Thomas distinguishes three levels in the natural inclinations. But from what he says elsewhere in the Summa, we can add a fourth level. As influenced by Aristotle's scientific theory of biological inheritance (GA 767b24-69b31), Thomas saw three levels of the human biological desires. These desires are "generic" as shared with other animals, "specific" as shared with other human beings as rational animals, or "temperamental" as showing the individually unique traits of a particular human being (ST, I-II, q 10, a 1, ad 3; q 46, a 5; q 51, a 1; q 63, a 1). There seems, then, to be four levels of natural inclinations: substantial nature, generic nature, specific nature, and temperamental nature.

Following the teaching of the Neoplatonic Book of Causes, Thomas sees the first level of reality as the creation of "being" (ens) or "existence" (esse). All substances seek the preservation of their being. Human beings share in this most fundamental level of reality in their natural inclination to survival. This corresponds to the natural biological desire for self-preservation.

Because of this natural desire for self-preservation, it belongs to natural law that killing in self-defense is justified, while unjustified killing of another human being is punished as murder (I-II, q 100, a 8, ad 3; II-II, q 64, a. 7).

As animals, human beings share in the natural inclinations of other animals, and particularly the mammalian animals that reproduce sexually and invest care in their offspring. In explaining this animal level of natural law, Thomas quotes from the ancient Roman jurist Ulpian: "Natural right is that which nature has taught all animals." Here the term "natural right" (ius naturale is interchangeable with "natural law" (lex naturalis). To illustrate the natural inclinations that human beings share with other animals, Ulpian referred to the sexual intercourse of male and female and the parental care of offspring as animal propensities that sustain human marriage and family life in conformity to natural law. Quoted at the beginning of Justinian's Institutes (533 A.D.), Ulpian's remarks entered the medieval tradition of natural law reasoning, and they were cited by Thomas when he explained natural law as rooted in the natural inclinations or natural instincts that human beings share with other animals. Each species of animal has a natural law corresponding to the natural inclinations of the species. The natural law for human beings is similar to the natural law of those animals who need to engage in the mammalian bonding between male and female and between parent and offspring. "Natural right in the strict sense" applies only to this level of common inclinations shared by human beings and other mammals (I-II, q 91, aa 4, 6; q 95, a 4, ad 1; II-II, q 57, a 3; Suppl, q 65, a 1, ad 4).

Thomas observes that unlike plants and inanimate entities, human beings and other intelligent animals display reason and desire in their movements (I, q 78, a 4; q 80, a 1; q 83, a 1; I-II, q 6, a 2; q 40, a 3; q 58, a 1; Commentary on Aristotle's "De Anima", secs. 629, 874). Intelligent animals consciously apprehend the objects of their desires, gather and assess information in their environment relevant to their desires, and then act according to their judgment of how best to satisfy their desires. In doing this, they learn to apprehend physical things and other animals as pleasurable or painful, useful or harmful, friendly or hostile. They act voluntarily in that they initiate acts as guided by some knowledge of their goals. They remember the past and anticipate the future. As social animals, they judge the intentions of other animals and communicate with them to act for common ends. They display and recognize social emotions such as love, hate, and anger. They learn from experience, and they transmit what they learn to others.

In so far as Thomas thus recognizes the continuity between human beings and other intelligent animals, he takes a position that is compatible with the Darwinian idea that the human species evolved from ancestral species of nonhuman animals, although Thomas never developed the idea of evolution. This supports Anthony Lisska's claim that Thomas's view of human nature and natural law is rooted in a "biological paradigm" (Aquinas's Theory of Natural Law: An Analytic Reconstruction [Oxford: Clarendon Press, 1996], pp. 68, 96-109, 131, 189-91, 198-201, 218-22, 258).

The biological character of Aquinas's reasoning about natural law as rooted in natural desires is clear in his account of marriage and familial bonding. He speaks of the human disposition to marriage as a "natural instinct of the human species" (SCG, bk. 3, chap. 123). On his account, the primary natural end of marriage is to secure the parental care of children, while the secondary natural end is to secure the conjugal bonding of male and female for a sexual division of labor in the household.

Among some animals, Aquinas observes, the female can care properly for her offspring on her own, and thus there is no natural need for any enduring bond between male and female. For those animals whose offspring do require care from both parents, however, nature implants an inclination for male and female to stay together to provide the necessary parental care (SCG, bk. 3, chaps. 122-23).

Just as is the case for those animals whose offspring could not survive or develop normally without parental care, human offspring depend upon parents (or parental surrogates) for their existence, their nourishment, and their education. To secure this natural end, nature instills in human beings natural desires for sexual coupling and parental care. Even if they do not have children, however, men and women naturally desire marital union because, not being self-sufficient, they seek the conjugal friendship of husband and wife sharing in household life.

Marriage as constituted by customary or legal rules, Aquinas says, is uniquely human, because such rules require a cognitive capacity for conceptual reasoning that no other animals have. Even so, human rules of marriage provide formal structure to natural desires that are ultimately rooted in the animal nature of human beings. Aquinas explains the natural laws of marriage in the light of Aristotle's biological studies of animal sexuality, reproduction, and parental care (compare Aquinas, SCG, bk. 3, chaps. 123-124; and Aristotle, HA, 571b3, 608b19, 610b35, 613a6, 613b33, 617a10).

The third level of natural law is uniquely human because it corresponds to the uniquely human capacity for reason, which gives human beings a self-conscious awareness in deliberately formulating a plan of life for the fullest satisfaction of their natural desires over a complete life. This includes not only social desires for living in society but also "the natural inclination to know the truth about God," which corresponds to what I have identified as the evolved natural desire for religious understanding.

Aquinas believes that the natural human desire to understand the causes of all effects leads to the desire to understand the ultimate causes--the uncaused causes--of everything, which can only be finally satisfied by the eternal contemplation of God in Heaven. The way to this supernatural happiness requires revealed religion and divine law, which surpasses natural law.

But even at the level of natural law, there is a "natural instinct" for reverence that supports natural religion. Moreover, it is natural for human laws to support religion in so far as it contributes to the moral order of human life (ST, I, q 12, a 1; I-II, q 3, a 8; q 99, a 3; II-II, q 81, a 5; q 85, a 1; SCG, I, 11; III, 25, 50-51, 57, 119).

Notice that the natural inclination "to know the truth about God" is not necessarily a natural inclination to know God. The "truth about God" might be atheism. This points to Aquinas's distinction between natural reason and supernatural revelation. Faith in revelation cannot be a matter of rational demonstration. So the natural inclination "to know the truth about God" seems to be the natural inclination to know the ultimate causes of things, which supports the life of philosophy or science. That's why the natural law precept following from this natural inclination is "shun ignorance."

Notice Thomas's remarkable silence about revelation in this article of the SUMMA. In this article, there is not a single reference to the Bible. The desire "to know the truth about God" is identified as a natural inclination requiring natural reason guided by the natural precept to "shun ignorance." From the point of view of natural law, it seems, "knowing the truth about God" is an exercise of philosophy or science in investigating the ultimate causes of things, which does not depend upon faith. Here we see the contrast between reason and revelation.

"To have faith is not in human nature," Thomas insists (II-II, q. 10, a. 1, ad 1).  To "know the truth about God" cannot be faith, because faith is beyond natural reason and can only come by a supernatural infusion from God (I-II, q. 104, a. 1, ad 3; II-II, q. 6, a. 1; q. 8, a. 1).  Of those who see the same miracle or hear the same sermon, some will believe, and others will not.  Natural reason by itself could never lead us to have faith, because faith must ultimately be a supernatural gift from God.

Although Darwinian science can neither confirm nor deny the supernatural truth of revelation and divine law, Darwinian science can explain natural religion as an expression of the evolved natural desire for religious understanding. We can see the evolution of religion in the evolved tendency of human beings to project their experience of mental intentionality and their "theory of mind" onto the universe as they move beyond nature to nature's God. We can also see how such religious belief reinforces the moral order of a human community.

At the level of temperamental nature, each human individual is unique in the innate dispositions that constitute individual identity. By natural temperament, "one man has a natural aptitude for science, another for fortitude, another for temperance, and in these ways, both intellectual and moral virtues are in us by way of natural aptitude, inchoatively, but not perfectly" (ST I-II, q. 63, a. 1).

So, for example, although sexual mating and parental care are natural inclinations for most human beings, some human beings are temperamentally inclined to refrain from sexual mating and parental care, and thus they are naturally suited for celibacy (ST, Suppl, q 41, a 2, ad 4).

This raises an interesting question. Aquinas condemns homosexuality as "contrary to nature," because the only natural sexual activity for human beings is heterosexual intercourse (ST, I-II, q 94, a 3, ad 2). But if homosexuality manifests a natural temperament of some individuals, who show a natural inclination for same-sex conjugal bonding, and if this does not hinder heterosexual marriage and parenting, could tolerance for homosexuality be warranted by natural law?

All of these levels of the natural inclinations can be studied by biological science because "the soul is united to the animal body" (ST, I, q. 76, a. 7). Even the "intellectual soul" of a human being is united to the human animal body, although the emergence of the human "intellectual soul" in the body of the human embryo requires a special infusion from God (ST, I, q. 116, a. 2).

Aquinas suggests, however, that this miraculous intervention by God in embryological development cannot be known by biological science, because it depends on faith, which cannot be rationally demonstrated. "Faith and reason are not about the same things," and therefore "the reasons employed by holy men to prove things that are of faith are not demonstrations" (ST, II-II, q. 1, a. 5). Thus, there remains an irreconciliable tension between science and faith, reason and revelation.

This explains why Pope John Paul II, in a statement to the Pontifical Academy of Sciences in 1996, accepted evolutionary science, while also insisting that "the spiritual soul is immediately created by God."

Considering what Aquinas says about the natural law of knowing the truth about God and shunning ignorance in the exercise of natural reason, we might wonder whether the reliance on faith rather than science violates natural law.

Aquinas does say, of course, that the ultimate end of human life is the supernatural happiness of the afterlife. But he is clear that this does not belong to natural law, because this supernatural realm can be known only by divine law. The moral and intellectual virtues that perfect our natural inclinations according to natural reason depend on purely natural human experience. Natural law is not directed to a supernatural end. Consequently, the theological virtues by which human beings are directed to a supernatural end must be directly infused by God. "The power of those naturally instilled principles does not extend beyond the capacity of nature. Consequently, man needs in addition to be perfected by other principles in relation to his supernatural end" (I-II, q. 63, a. 3, ad 3).

Is Aquinas covertly taking the side of scientific reason against biblical revelation, even as he promotes the most rational interpretation of biblical revelation because of its moral benefits?

Some posts on related themes can be found here, here, here, here, here, here, here, and here.

The Pope's statement can be found here.

Tuesday, June 21, 2011

Evolution as Secondary Causality: Darwin and Aquinas

In rejecting the "theory of special creation" and defending the "theory of natural selection," Charles Darwin explained the natural evolution of species as due to "secondary causes." In assuming dual causation--distinguishing "secondary causes" from "primary causes"--Darwin adopted a metaphysical principle that was originally formulated by Thomas Aquinas and other Dominican theologians of the Middle Ages, who had drawn the idea from some medieval Muslim philosophers.

This principle of dual causation was crucial for reconciling reason and revelation--Athens and Jerusalem--so that Jews, Muslims, and Christians could embrace Aristotle's natural philosophy as compatible with their religious belief in God as Creator. This reconciliation of Biblical religion and Aristotelian naturalism provided the cultural conditions for the emergence of modern science in the Western world.

The tension between religion and science continues to stir emotional debate today, particularly among those Christians and Muslims who worry about whether evolutionary science is compatible with their religious beliefs. The principle of dual causality is crucial today for those religious believers who want to reconcile biblical creationism and Darwinian evolution.

Darwin's novel contribution was in extending the principle of dual causation to allow for the origin of species and the emergence of human morality through the "secondary causes" of natural evolutionary laws.

In the concluding chapter of The Origin of Species, Darwin tried to persuade Christian creationists that it was a nobler conception of the Creator to see Him as working through the secondary causes of evolution rather than having to specially create each form of life by miraculous intervention.

To my mind it accords better with what we know of the laws impressed on matter by the Creator, that the production and extinction of the past and present inhabitants of the world should have been due to secondary causes, like those determining the birth and death of the individual. When I view all beings not as special creations, but as the lineal descendants of some few beings which lived long before the first bed of the Cambrian system was deposited, they seem to me to become ennobled.

In the sixth edition of the Origin, Darwin quoted from his friend the Reverend Charles Kingsley, who had written that he had "gradually learnt to see that it is just as noble a conception of the Deity to believe that He created a few original forms capable of self-development into other and needful forms, as to believe that He required a fresh act of creation to supply the voids caused by the actions of His laws."

In his Autobiography, Darwin described "the extreme difficulty or rather impossibility of conceiving this immense and wonderful universe, including man with his capacity of looking far backwards and far into futurity, as the result of blind chance or necessity. When thus reflecting I feel compelled to look to a First Cause having an intelligent mind in some degree analogous to that of man; and I deserve to be called a Theist."

But then he indicated that since writing the Origin, he had begun to doubt this. He wondered whether the human tendency to see a necessary connection between cause and effect might be merely a product of inherited experience embedded by evolution in the human brain. Or it might be that the cultural tradition of belief in God, inculcated in the minds of children, has made it hard for many human beings to throw off their religious beliefs. "I cannot pretend to throw the least light on such abstruse problems," he observed. "The mystery of the beginning of all things is insoluble by us; and I for one must be content to remain an Agnostic."

Darwin was also concerned that if we believe that God has designed everything in the world down to the last detail, then we must hold Him responsible for all the evil in the world. He thought that evolution could explain the occurence of evil in a world in which God is not directly responsible for everything.

In arguing that it was "nobler" for the Creator as First Cause to confer on His creatures the dignity of acting as secondary causes, Darwin was continuing a tradition of thought stretching back to the Middle Ages. Some biblical believers assumed that the glory of God as the omnipotent Creator required that He should be the only cause, so that He would have no need for intermediary processes to carry out His will. But Aquinas and others argued that it denigrated God's goodness to say that He was not good enough or powerful enough to give creatures their own causal power. To allow creatures to exercise power as secondary causes conferred dignity on them and glory to the Creator. "To take away their proper actions from things is to disparage the divine goodness" (SCG, III, 69, 16).

Moreover, Aquinas insisted, this dual causality was the necessary condition for natural science: "if created things have no actions productive of effects, it follows that no nature of anything would ever be known through the effect. And thus, all the knowledge of natural science is taken away from us, for the demonstrations in it are chiefly derived from the effect" (SCG, III, 69, 18).

This Christian defense of natural science was controversial in the Middle Ages, because natural science was understood primarily as coming from the pagan natural philosophy of Aristotle. Up to the twelfth century, most of the writings of Plato and Aristotle were not available in the Christian West. Christians could read only Plato's Timaeus and Aristotle's logical works. The theological cosmology of the Timaeus was interpreted as resembling Biblical creationism. And, similarly, Aristotle's logical works posed no challenge to Christian beliefs. But then in the twelfth century, the Arabic translations of Plato and Aristotle were translated into Latin, and for the first time, Christians could read Aristotle's books of natural philosophy--including his biological works--for the first time. Since Aristotle's science did not recognize a Creator God or a supernatural realm, Aristotle's books of natural science were banned at the University of Paris and other Christian universities. Those promoting Aristotelian science were subject to punishment by the Inquisition. Even Aquinas himself was suspected of promoting heretical doctrines in teaching Aristotelian science. Despite this persecution, Aristotelian science prevailed and even became part of the regular curriculum at Christian universities, but only because Aquinas and others were able to persuade the Church authorities that Aristotle's account of nature and its causal laws could be understood as belonging to a realm of secondary causes, and thus compatible with belief in God as First Cause.

A similar debate had occurred earlier in the Islamic world. When the works of Plato and Aristotle were translated into Arabic by Muslim scholars in the eighth century, some Muslim theologians denounced this pagan knowledge as contrary to the revealed wisdom of the Koran. The Muslim proponents of Greek philosophy--particularly, Avicenna, Alfarabi, and Averroes--had to show how the natural philosophy or science of the Greeks was compatible with the Koran. Drawing on certain Platonic and Neo-Platonic texts, they developed the principle of dual causation, so that the study of the causal laws of nature could be seen as compatible with believing in God's omnipotence as First Cause.

Perhaps the earliest source of the idea of dual causation is in Plato's Timaeus (46d-e). This idea was further developed in some of the Neo-Platonic texts, and then concisely stated in The Book of Causes, an anonymous work written probably in the ninth or tenth century in Baghdad. When this book was translated into Latin in Toledo in the twelfth century, it became the primary source for this idea in the Christian West.

For at least 300 years, if not longer, science and philosophy flourished in the Islamic world. But then, beginning in the twelfth century, some Muslim theologians began to attack this intellectual movement as irreligious. The most influential of these was Abu Hamid Muhammad al-Ghazali, particularly in his work The Incoherence of the Philosophers. Representing the Asharite school of Islamic theology, al-Ghazali argued that God is the only cause, and therefore what human beings habitually regard as sequences of natural causes and effects are only contingent events that are arbitrarily decreed by God. Thus, there is no inherent necessity in the order of nature. To look for lawful causal necessities in nature--as scientists and philosophers do--is a blasphemous denial of God's unconstrained power.

Against al-Ghazali's Incoherence of the Philosophers, Averroes wrote his own book The Incoherence of the Incoherence to defend Greek science and philosophy as consistent with Muslim beliefs.

This debate continues today. Remarkably, the Muslim world today seems inhospitable to science, because so many Muslims assume that modern science is contrary to their religious beliefs. In many Muslim countries, the majority of believers reject evolutionary science as contradicting the creationism of the Koran. We tend to assume that the creation/evolution debate is mostly a product of fundamentalist Christian culture in the United States. But, in fact, this same debate is carried out in the Muslim world. A recent article in The Chronicle of Higher Education surveys this current debate over whether science--and particularly, evolutionary science--can be accepted by Muslim believers. It should be noted that some of the Muslim scientists defending evolution as compatible with the Koran use the same arguments that Averroes used against al-Ghazali, arguments that depend upon the principle of dual causation.

Similarly, among Christians in the Western World today, the interpretation of evolution as secondary causality continues to be the fundamental idea for justifying theistic evolution, which has been embraced by Christian scientists like Francis Collins, Christian writers like C. S. Lewis, and Christian politicians like Mitt Romney.

The religious appeal to God as the uncaused cause of nature cannot be refuted by reason. All natural explanations of the world--including Darwinian science--must assume that ultimately the order of nature is the unexplained ground of all explanation. But there is no way to deny the possibility that nature itself is the contingent product of nature's God.

Al-Ghazali, The Incoherence of the Philosophers, trans. Michael E. Marmura (Provo, UT: Brigham Young University, 2000).

The Book of Causes, trans. Dennis J. Brand (Milwaukee, WI: Marquette University Press, 1984).

Maurer, Armand, "Darwin, Thomists, and Secondary Causality," The Review of Metaphysics 57 (March 2004): 491-514.

Rubenstein, Richard, Aristotle's Children: How Christians, Muslims, and Jews Rediscovered Ancient Wisdom and Illuminated the Middle Ages (Orlando, FL: Harcourt, 2003).

Aquinas's reconciliation of Arabic and Greek science with Christian theology is beautifully depicted in Francesco Traini's altarpiece "Triumph of St. Thomas Aquinas", which is nicely reproduced as part of the cover for Rubenstein's book.

Some blog posts on related themes can be found herehere, here, here, here, here, here, here, here, here, here, here, here, here, here.

Wednesday, June 08, 2011

The Evolutionary Neuroscience of Lockean Ownership

This post continues some thoughts from my previous posts on Churchland's naturalism and the neuroscience of self-awareness.

In many of my posts and published writings over the years, I have argued that my reasoning for "Darwinian natural right" could support much of Thomas Aquinas's reasoning for natural law and John Locke's reasoning for natural rights. If I am right about this, then the ideas of "natural right," "natural law," and "natural rights" should all be ultimately explicable as rooted in the evolutionary neuroscience of human social order. If we can explain human sociality as the outcome of mammalian evolution, then there should be mechanisms in the human nervous system to support the moral psychology of human social life. Advances in human social neuroscience should therefore explain the neural basis for the human social nature studied by political philosophers.

Consider, for example, Locke's argument for natural rights as rooted in divine ownership and self-ownership.

In the Second Treatise, Locke grounds his law of nature in the "workmanship" of God in creating human beings:

The State of Nature has a Law of Nature to govern it, which obliges every one: And Reason, which is that Law, teaches al Mankind, who will be consult it, that being all equal and independent, no one ought to harm another in his Life, Health, Liberty, or Possessions. For Men being all the Workmanship of one Omnipotent, and infinitely wise Maker; All the Servants of one Sovereign Master, sent into the World by his order and about his business, they are his Property, whose Workmanship they are, made to last during his, not one anothers Pleasure. And being furnished with like Faculties, sharing all in one Community of Nature, there cannot be supposed any such Subordination among us, that may Authorize us to destroy one another, as if we were made for one anothers uses, as the inferior ranks of Creatures are for ours. (sec. 6)

Those scholarly interpreters--like James Tully and Brian Tierney--who see Locke as a natural law theorist in the tradition of Aquinas and Richard Hooker emphasize this Lockean declaration of creationist theology, in which "natural rights" can be understood as permissions within the order of natural law as established by God.

But those--like Leo Strauss and Michael Zuckert--who see Locke as a modern natural rights theorist in the tradition of Hobbes emphasize Locke's affirmation of of individual self-ownership in his chapter on property.

Though the Earth, and all inferior Creatures be common to all Men, yet every Man has a Property in his own Person. This no Body has any Right to but himself. The Labour of his Body, and the Work of his Hands, we may say, are properly his. Whatsoever then he removes out of the State that Nature hath provided, and left it in, he hath mixed his Labour with, and joyned to it something that is his own, and thereby makes it his Property. (sec. 27)

From all which it is evident, that though the things of Nature are given in common, yet Man (by being Master of himself), and Proprietor of his own Person, and the Actions or Labour of it) had still in himself the great foundation of Property. (sec. 44)

Here, Zuckert argues, the foundation of Locke's political philosophy of natural rights is not God's ownership of the world and His rule by natural law, but rather the idea that human beings have natural rights because they are self-owners. Moreover, Zuckert insists, it is this natural autonomy of human beings, rather than their natural subordination to God, that informs the modern understanding of human rights.

Here we see a tension or contradiction that runs through much of our modern debate about liberal political thought. On the one hand, some people argue that human rights depend upon religious belief in creationism--in the the idea that human beings have been created by God and endowed by Him with rights (as asserted by the Declaration of Independence). On the other hand, other people argue that human rights depend on a purely secular belief in individual autonomy, which includes the freedom of individuals from any politically enforced establishment of religion. So how we interpret Locke has implications for this continuing debate in liberal societies over the relationship between religious belief and liberal politics.

Recently, Adam Seagrave--one of Zuckert's students--has offered an interpretation of Locke that resolves this tension, so that Locke's arguments for divine ownership and self-ownership can be compatible. The key is in seeing how divine ownership and self-ownership apply to two different but concurrent facets of human beings.

On the one hand, God has created the generic traits of human beings as belonging to the same human species--"being furnished with like Faculties, sharing all in one Community of Nature"--as distinguished in their uniquely human nature from other animals--"the inferior ranks of Creatures."

On the other hand, human beings as distinguished from one another have each a "person" or "self" that arises as the product of each individual's self-conscious workmanship.

It seems that in creating human beings in His own image as a creative mind, God created them with the capacity for self-conscious creating. Thus, God created human beings as potential self-creators and thus self-owners. Human beings are created co-creators. (TT.I.30, 39; II.44). Consequently, "in respect of God the Maker of Heaven and Earth," human beings are God's property; but "in respect of one another," they have property in themselves and in whatever they appropriate to themselves (TT.I.39).

Seagrave thinks this opens up a Lockean resolution to the contuing debate over the relationship between religion and politics in liberal regimes. He writes:

The premise of self-ownership is not derived from, and may be conceived entirely independent of, the premise of Divine ownership. Similarly, the premise of Divine ownership may be conceived independently from the premise of self-ownership. The two premises considered together, however, are compatible and even in profound harmony with one another. . . . This framework opens up a true common ground, rather than a mere overlap, between atheist and religious citizens of liberal democracies in the idea of self-ownership despite persistent disagreement regarding the premise of Divine ownership. This common ground is also potentially open to citizens subscribing to very different religious doctrines; despite the persistence of heated religious controversy, both premises that enter into the "nesting" property framework may be accepted by such citizens.

I wonder, however, how Seagrave would explain Locke's argument--in the "Letter Concerning Toleration"--that atheists must not be tolerated, because "the taking away of God, tho but even in thought, dissolves all." If this is what Locke believes, then how can Locke provide common ground for atheists and religious believers?

What Seagrave says about the compatibility of self-ownership and Divine ownership as grounds for natural rights restates what was said by Richard Overton in 1646.  Overton was one of the Levellers in the English Civil War.  In An Arrow Against All Tyrants, he argued for religious liberty as grounded in "self-propriety"--the property that a man has in himself.  But he also assumed that this self-ownership manifested a natural instinct implanted by God, and thus the equality of self-ownership was compatible with the equality of human beings as created in God's image.  This could have been the original source for Locke's reasoning.  Seagrave does not Overton, however.

In his Essay Concerning Human Understanding, Locke identifies a "person" or "self" as "a thinking intelligent being, that has reason and reflection, and can consider itself as itself, the same thinking thing, in different times and places." All the parts of a human body are vitally united to this thinking self, "so that we feel when they are touched, and are affected by, and conscious of good or harm that happens to them, are a part of ourselves; i.e. of our thinking conscious self." So that "the limbs of his body are to every one a part of himself; he sympathizes and is concerned for them." "Self is that conscious thinking thing . . . which is sensible or conscious of pleasure and pain, capable of happiness or misery, and so is concerned for itself, as far as that consciousness extends. Thus every one finds that, whilst comprehended under that consciousness, the little finger is as much a part of himself as what is most so" (II.xxvii.9, 11, 17).

This Lockean conception of individual personhood as embodied self-conscious awareness of, and emotional concern for, the survival and well-being of the body can now be confirmed as manifest in the human nervous system as a product of mammalian evolution. If we follow Antonio Damasio's "somatic marker hypothesis" and Bud Craig's neuroanatomical argument, we can identify the self-ownership of the person as the activity of the anterior insular cortex (AIC) in constituting the subjective awareness of the individual in caring for one's self and for others to whom one is attached.

This mammalian extension of care to offspring, sexual mates, and other social partners is identified by Locke when he explains human sociality as rooted in the biological inclinations for survival, mating, and reproduction (TT.I.86-89; II.54-56, 77-84).

As intensely social mammals who feel social pain as well as physical pain, and as animals with uniquely human capacities for deliberation, language, and symbolic learning, we develop moral norms expressed in moral sentiments and moral traditions. The idea of "rights" is one way that we formulate these norms as developed through individual and social experience. The modern tradition of "natural rights" or "human rights" manifests that practical experience by which we negotiate the terms of our social life. Natural desires become natural rights when rational creatures reflect on the conditions for satisfying their desires in cooperation with others.

But even if we conclude that evolutionary neuroscience can support a Lockean conception of natural rights as rooted in natural self-ownership, we might wonder about whether this science can also support the Lockean conception of divine ownership.

Since its first formulation by Darwin, evolutionary science has often been assumed to be atheistic. And yet Darwin himself left room for the Divine Creator as First Cause of those original laws of the universe that allowed the natural evolution of life to unfold. Moreover, Darwin recognized the importance of religious belief for moral progress, although he implied that such religious belief was not absolutely necessary.

The Darwinian understanding of the natural moral sense resembles Locke in his appeal to "God and Nature" or Revelation and Reason, so that divine right becomes natural right insofar as Nature's God manifests His will in the way he has "ordered the course of nature" (TT.I.88-90; II.25). We can discern the law of nature by reflecting on our natural experience of the natural world. The atheistic naturalist will not go any further, because the natural order of things will be taken as the unexplained ground of all explanation. But the religious believer will look beyond nature to nature's God as the unexplained ground of all explanation. Darwinian science neither affirms nor denies such religious beliefs. But it does affirm that the moral and political order of life can be rooted in evolved human nature without any necessity for religious belief.

Whether Darwinian natural right can reconcile Thomistic natural law and Lockean natural rights requires more commentary than I can provide here. But I will offer one comment on what Seagrave says about comparing natural law and natural rights.

Seagrave contrasts the "objective moral standard" of traditional natural law with the "subjective rights" of individuals in the Lockean teaching. Here he follows the lead of Strauss, and in doing that, he makes Strauss's mistake in failing to see that we can affirm the objectivity of the generic goods rooted in human nature, while also affirming the individuality in the expression of those generic human goods by particular individuals.

Darwinian natural right supports this by recognizing the universal natural desires of evolved human nature, while also recognizing the individualized expression of those natural desires in the personal life of human beings. In my argument, the twenty natural natural desires constitute the objective standard of the human good. But each individual will organize and rank those natural desires in a manner that is appropriate for the individual.

We can recognize the liberal regime as the best regime because it secures the conditions in which individuals are free to organize their social lives in the pursuit of the objective goods of human life without coercive enforcement of any one conception of the good upon all.

This is what I have defended in some previous posts as Aristotelian liberalism, which combines Aristotelian social virtue and Lockean political liberty.

As I have indicated in some previous posts, we can see in Locke's appeal to two principles--"divine workmanship" and "self-ownership"--the tension between metaphysical ethics and empirical ethics. If human beings are created by God in His Image, then they have a divinely created worth that cannot be properly denied by those who would deprive them of their sacred rights. But if each human being is naturally inclined to take possession of himself in mind and body, and if each man can see that all other men assert the same self-possession, then this human experience of self-ownership could be a purely secular ground of human rights. The modern move towards understanding human rights as rooted in the secular experience of empathy and moral emotions relies on Locke's secular principle of self-ownership without the religious principle of divine workmanship.

A Darwinian moral psychology and modern neuroscience can explain this secular history of human rights as an extension of the empathetic or sympathetic bonds that have evolved for mammalian social life. Locke anticipated this in so far as he stressed the natural sociality of human beings as a species that cannot survive or reproduce without extensive and intensive parental care of offspring.


S. Adam Seagrave, "Self-Ownership vs. Divine Ownership: A Lockean Solution to a Liberal Democratic Dilemma," American Journal of Political Science, 2011.

Seagrave, "How Old Are Modern Rights? On the Lockean Roots of Contemporary Human Rights Discourse," The Journal of the History of Ideas 72 (April 2011): 305-327

Some of my posts on related themes can be found here, here, here, here, here, here, here, here, here, here, here, here, here, and here.

Bud Craig on Interoception and the Neuroscience of Self-Awareness

Ever since I first read Antonio Damasio's Descartes' Error: Emotion, Reason, and the Human Brain (1994), I have been impressed by his "somatic marker hypothesis" for explaining the importance of emotion in decision-making and consciousness. Building on an idea proposed by William James and Carl Lange, Damasio believes that emotions arise from physiological states of the body, so that, for example, the emotion of fear arises from the physiological disturbance of the body associated with some fearful event. Emotions help us to make decisions by assigning emotional valence to our choices. Through imaginative projection, we can foresee the emotional outcome of a choice by anticipating how we will feel--our somatic markers--if we make that choice, and thus we might avoid a choice with fearful associations. Ultimately, this emotional decision-making mechanism can be explained as an evolutionary adaptation to secure the survival and well-being of the body.

I introduced some of Damasio's research into my chapter on psychopathy in Darwinian Natural Right, because it's likely that the brains of psychopaths are abnormal in their failure to process social emotions such as fear, guilt, and shame, so that they don't feel the moral sentiments that guide the behavior of normal people.

This line of thought has been extended by A. D. (Bud) Craig, a functional neuroanatomist at the Barrow Neurological Foundation. He has traced out the fundamental neuroanatomical basis for all human emotions, and he has argued that this shows how the neural substrates for human self-awareness or consciousness are based on the neural representation of the physiological state (the homeostasis) of one's body. This manifests the embodiment of emotional self-consciousness. In particular, he argues that there is a phylogenetically novel sensory pathway in primates, most fully developed in human beings, that provides for a self-conscious integration of the physiological condition of the body (the material "self") with one's sensory environment, with one's motivational condition, and with one's social situation in the anterior insular cortex (AIC).

In imaging studies of emotion, the AIC is jointly activated with the anterior cingulate cortex (ACC). The AIC seems to be the primary site for self-awareness based on representations of the feelings from the body, while the ACC seems to be the site for the initiation of behavior, which thus provides volitional agency.

Wikipedia articles provide some good diagrams and analysis of the AIC and ACC here and here.

My special interest in all of this is in how it might explain the evolutionary neurophysiological basis for Thomas Aquinas's account of natural law or John Locke's account of natural rights. Reasoning about natural law or natural rights ultimately depends on discerning natural human inclinations, such as self-preservation, property, social attachment, practical judgment, and intellectual understanding, which correspond to what I have identified as the twenty natural desires. Evolutionary neuroscience explains how the human nervous system has evolved to serve those natural inclinations or desires. The concrete expression of those natural inclinations will vary according to individual temperament, individual life history, and cultural circumstances. But there will be a universal human pattern that manifests the evolved natural needs of human beings as the very smart social mammals that they are.

The evolution of mammalian social behavior depends on the evolution of pain or "negative affect," which includes pain, fear, panic, and anxiety. In all vertebrates, fear and pain are represented in the brainstem and hypothalamus as signals to elicit self-preserving behavior. In mammalian evolution, these neural mechanisms are modified so that animals care for their offspring as well as themselves. This includes modifying the cortex of the mammalian brain to elaborate the representation of pain to include anxiety tied to separation from or threat to loved ones.

Craig's research clarifies this neural evolution of pain by classifying pain as a homeostatic emotion rather than as a sensation of touch. Pain belongs to "interoception"--the sense of the physiological condition of the body--and it is therefore part of the evolved mechanisms for self-preservation.

The insular cortex receives signals from all the tissues of the body, and these signals are integrated with physical and social stimuli from outside the body and with the memory of past experiences as well as imaginative projections of future experiences. This supports a general awareness of the body's condition in space and time. The ACC can then be activated to motivate behavior to correct whatever is wrong. This neural processing mechanism seems to be unique to primates, but it's more highly developed in human beings.

Both the insular cortex and the ACC respond not only to physical pain from bodily injury but also social pain from social injury. It seems that in mammalian evolution, the neural circuitry for physical pain was appropriated for registering social pain in animals adapted for social attachment. Mammals must care for the survival and well-being not only of themselves but of others to whom they are attached. Extending the neural mechanisms originally evolved for individual self-preservation to include the welfare of offspring and social partners secures mammalian social order. The uniquely human evolution of the neocortex elaborates this mammalian development to sustain human love and concern for others.

When we use the language of physical pain to describe our social pain ("a broken heart"), we recognize the embodiment of our natural social consciousness, in which our mind, our brain, our body, and our social life are inseparably intertwined.

If this is true, then the Platonic idea of the disembodied immortality of the soul is nonsensical.


Patricia Churchland, Braintrust: What Neuroscience Tells Us about Morality (Princeton: Princeton University Press, 2011)

A. D. (Bud) Craig, "How Do You Feel? Interoception: The Sense of the Physiological Condition of the Body," Nature Reviews Neuroscience 3 (August 2002): 655-666

Craig, "A New View of Pain as a Homeostatic Emotion," Trends in Neurosciences 26 (June 2003): 303-307

Craig, "Interoception and Emotion: A Neuroanatomical Perspective," In Handbook of Emotions, 3rd ed., edited by Michael Lewis, Jeannette Haviland-Jones, and Lisa Barrett, 272-288. New York: Guilford, 2008.

Craig, "How Do You Feel--Now? The Anterior Insula and Human Awareness," Nature Reviews Neuroscience 10 (January 2009): 59-70.

Naomi I. Eisenberger and Matthew D. Lieberman, "Why Rejection Hurts: A Common Neural Alarm System for Physical and Social Pain," Trends in Cognitive Sciences 8 (July 2004): 294-300.

A few of the many posts on related themes can be found here, here, here, and here.

Sunday, June 05, 2011

Strauss's Plato, Churchland's Naturalism, and the Neurobiology of Care

In Braintrust: What Neuroscience Tells Us About Morality (Princeton University Press, 2011), Patricia Churchland explains "the neural platform for morality" by showing how the neurochemistry of mammalian attachment provides the natural ground for human morality and social order. This adds to her life-long project for laying out the philosophic implications of a neuroscientific naturalism.

This might seem far away from the Platonic political philosophy of Leo Strauss. But in fact, I see a fundamental agreement between the Straussian reading of Plato and the Churchlandian account of the neurobiology of morality--particularly, in the theme of human care within an uncaring universe.

Plato is well known for teaching a moral cosmology that shaped the Western intellectual tradition--"The Great Chain of Being"--for almost 2,000 years. According to this view, the moral order of human life depends on a cosmic moral order in which everything has been intelligently designed for the Good, and thus the human good requires that human beings imitate somehow the cosmic good.

Remarkably, Strauss and his followers argue that a careful reading of Plato shows that this is his exoteric teaching, the teaching for the unphilosophic multitude, but not the esoteric teaching, the teaching for the philosophic few. The philosophic teaching of Plato's Socrates suggests that the cosmos is morally neutral--that the cosmos does not care for human beings. Thus, Plato is not a Platonist.

It follows then--as indicated by Joseph Cropsey, Catherine Zuckert, and other followers of Strauss--that the moral and political order of human life depends on human "care": human beings care about their existence within an uncaring world of nature and without any divinity to care for them.

Churchland elaborates the same theme and indicates how modern neuroscience is beginning to explain the evolved neurobiological mechanisms supporting human care. As shaped by evolutionary history, nervous systems are organized to take care of the body. Animals with neural adaptations inclined to care for themselves and for their well-being are selected over those that neglect their self-preservation. In mammals, this caring for oneself is extended into care for others--for one's offspring, for one's mate, for one's kin, and for others in one's group. We are now beginning to explain how this works through the neurochemistry of oxytocin and vasopressin, which support attachment and bonding. This sustains the basic social desires or sentiments that lead to human morality.

This is not a satisfying view of morality for those people who want their morality grounded in cosmic standards of right and wrong, as in the moral commands of a divine lawgiver. An evolved human morality is purely human in being adapted to human needs and desires, and thus it has no cosmic support. For many contemporary moral philosophers, this would mean that human morality is an illusion because it lacks "normativity" in so far as it lacks any support by a cosmic God, cosmic Reason, or cosmic Nature.

Platonism is associated with the idea of moral cosmology--the Idea of the Good. But Strauss and his students see in Plato's Socrates an implied skepticism about any moral cosmology.

Churchland sees this as well. In her comments on Plato's Euthyphro, she writes:

Always modest, Socrates confesses ignorance of the answer to his own questions concerning the source of morality. The pattern of questioning strongly hints, however, that whatever it is that makes something good or just or right is rooted in the nature of humans and the society we make, not in the nature of the gods we invent. There is something about the facts concerning human needs and human nature that entails that some social practices are better than others, that some human behavior cannot be tolerated, and that some forms of punishment are needed. This does not mean that moral practices are mere conventions, on par with using a fork or wearing a hat to a funeral. (196)

This suggests a fundamental continuity between Straussian Platonic naturalism and Churchlandian Darwinian naturalism.

A few of the relevant blog posts can be found here, here, and here.

Friday, June 03, 2011

The Role of Reason in Evolutionary Spontaneous Orders

"Whenever we see a well ordered arrangement of things or men we instinctively assume that someone has intentionally placed them in that way."

That quotation from Michael Polanyi's The Logic of Liberty nicely captures one of the fundamental problems in political philosophy and the social sciences. Because of our common experience of intelligently designed order through the intentional actions of ourselves and others, we "instinctively" project such intentionality onto any well ordered arrangement in the physical world or the social world. The appeal of natural theology and "intelligent design theory" arises from such anthropomorphic projections of intentionality, so that we see the whole universe as governed by Mind. Similarly, we assume that social order must arise from the intelligent planning of a human mind or group of minds. This fails to recognize, however, how the most complex social orders arise not by intentional design but as the unintended outcome of human interactions in which the result could not have been foreseen or understood by any of the individuals involved. This is what Polanyi called "spontaneous order."

In the history of political philosophy, beginning in ancient Greece, it took over 2,000 years before the idea of spontaneous order was clearly formulated for the first time in the Scottish Enlightenment of the 18th century (in the writings of Adam Ferguson, David Hume, and Adam Smith). This Scottish theory of spontaneous order was then picked up by Charles Darwin and developed as his theory of evolution to explain how the complex order of the living world, including human beings, could have arisen from inherited variation and natural selection without being planned out by intelligent design.

As indicated by the statement on the masthead of this blog, this theory of evolved spontaneous order runs through my argument for Darwinian liberal conservatism.

Perhaps the single best survey of the intellectual history of the theory of spontaneous order is Norman Barry's "The Tradition of Spontaneous Order," Literature of Liberty, 5 (Summer 1982), pp. 7-58, which is available online at the Liberty Fund's "Online Library of Liberty" website. Barry traces this history from the Scholastic "School of Salamanca" to the Scottish philosophers to Carl Menger and the Austrian School economists and, finally, to F. A. Hayek's revival of this tradition in the second half of the 20th century.

Originally, the idea of spontaneous order came most clearly from the explanation of how market order arises through the mechanism of a price system. We can see this, of course, in Adam Smith's Wealth of Nations. But we can also see Smith extending this theory of spontaneous order to explain moral order (in his Theory of Moral Sentiments)legal order (in his Lectures of Jurisprudence), and linguistic order (in his Considerations Concerning the First Formation of Languages). Menger and Hayek continued in this tradition.

Like me, Barry is impressed by the profound ways in which Hayek deepened this theory of spontaneous order, while also seeing weaknesses. One major weakness comes from Hayek pushing his antirationalist position so hard that he almost denies the role of reason in criticizing or correcting spontaneous order traditions, and thus he falls into a relativism that subverts his commitment to classical liberal principles. Other critics of Hayek--including many classical liberal critics--have made this criticism.

Although I agree with Barry on this point, I don't agree with his claim that Hayek's mistake comes from the influence of Darwinian evolutionary theory. I suggest that Hayek's mistake comes from his failure to see how Darwin's theory of human evolution recognizes the decisive role of human reason in social order, although that reason is constrained by the spontaneous orders of genetic evolution and cultural evolution. (This has come up in some of my recent posts on Hayek and evolution.)

Barry introduces the problem in this way:

The role of 'reason' is crucially important here because the theorists of spontaneous order are commonly associated with the anti-rationalist tradition in social thought. However, this does not mean that the doctrine turns upon any kind of irrationalism, or that the persistence and continuity of social systems is a product of divine intervention or some other extraterrestrial force which is invulnerable to rational explanation. Rather, the position is that originally formulated by David Hume. Hume argued that a pure and unaided human reason is incapable of determining a priori those moral and legal norms which are required for the servicing of a social order. In addition, Hume maintained that tradition, experience, and general uniformities in human nature themselves contain the guidelines for appropriate social conduct. In other words, so far from being irrationalist, the Humean argument is that rationality should be used to 'whittle down' the exaggerated claims made on behalf of reason by th Enlightenment philosophes. The danger here, however, is that the doctrine of spontaneous evolution may collapse into a certain kind of relativism: the elimination of the role of reason from making universal statements about the appropriate structure of a social order may well tempt the social theorist into accepting a given structure of rules merely because it is the product of traditional processes.

Barry sees Hayek leaning towards relativism because Hayek fails to distinguish "two senses of spontaneous order: noncoercive emergent patterns vs. 'survival of the fittest'" (11). By associating spontaneous order with a Darwinian order of evolutionary survival, Hayek falls into relativism. "For if the criterion of social value is survival in an evolutionary process, what can be said against those institutions which, although they may embody anti-liberal values, have survived?" (30). Barry observes: "The difficulty with Hayek's analysis is that social evolution does not necessarily culminate in the classical liberalism that he so clearly favors: there are as many non-liberal institutions which have survived. . . . If we are intellectually tied to tradition, and if our 'reason' is too fragile an instrument to recommend satisfactory alternatives, how are we to evaluate critically that statist and anti-individualist order of society which seems to have as much claim to be a product of evolution as any other social structure?" (46) One good example of this problem is that while Hayek favors the spontaneous order of British common law as superior to statutory law, the spontaneous emergence of parliamentary sovereignty has subverted the common law and the liberal order (16, 46).

Barry also rightly observes that Menger, who had such a powerful influence on Hayek's understanding of spontaneous order, did not deny the importance of reason and constructivist rationalism the way Hayek did. Menger did not assume that spontaneous evolved rules were always superior to deliberately designed rules. Menger believed that reason could criticize the outcomes of undesigned traditions and try to correct them (33, 52). After all, as even Hayek conceded, the successful functioning of a spontaneous order always depends on a legal and political framework that is subject to rational criticism and deliberate design.

Barry is mistaken, however, in attributing this mistake of Hayek to Darwinian evolutionary theory. The Darwinian evolutionary explanation of social order--including economic, moral, legal, and political order--sees a complex interaction of human nature, human culture, and human reason. This is evident in Darwin's account of the evolution of the moral sense in The Descent of Man, in which the emergence of human morality requires social instincts, habituation, language, and deliberation. "Ultimately," Darwin concluded, "our moral sense or conscience becomes a highly complex sentiment--originating in the social instincts, largely guided by the approbation of our fellow-men, ruled by reason, self-interest, and in later times by deep religious feelings, and confirmed by instruction and habit."

In Darwinian Conservatism (Chapter 2), I lay out this Darwinian explanation of the moral sense as moving through three levels of human experience: moral sentiments, moral traditions, and moral judgments. Moreover, by looking to the twenty natural desires of evolved human nature, we can judge moral, legal, and political traditions by how well they satisfy those natural desires.

The role of reason in this evolutionary understanding of social order is exactly what Barry says about Hume's position as being antirationalist but not irrationalist. Unaided reason--abstract or a priori reason--cannot by itself design a moral, legal, or political order. Reason needs the lessons coming from "tradition, experience, and general uniformities in human nature," but within the constraints set by our evolved human nature and our evolved human traditions, we can exercise practical judgment in deciding particular cases and devising general rules to promote the fullest satisfaction of our desires.

The instinctive human tendency to look for intelligent-design explanations for order underlies the tradition of Platonic moral cosmology and the attempt to explain the intelligibility of the whole as intelligently designed. The Straussians have struggled with this in their reading of Plato's dialogues. This was the subject of a series of my posts in the summer of 2009.