Does Believing in God Arise from Our Evolved Theory of Mind?

In God and Other Minds: A Study of the Rational Justification of Belief in God (published in 1967 and 1990), Alvin Plantinga offered assessments of the various arguments for believing in God. He concluded that the best argument was based on the analogy between believing in other human minds and believing in the Divine Mind. Although we have direct access to our own minds through subjective experience, we have no direct evidence for other human minds. But except for the radical solipsist, we regard belief in other human minds as a reasonable inference from our experience with other human beings. Similarly, we might conclude that although we have no direct, observational evidence for God's existence, we can reasonably infer the existence of a Divine Mind as a more perfect version of our human mind. Plantinga concluded: "if my belief in other minds is rational, so is my belief in God. But obviously the former is rational; so, therefore, is the latter."

(I doubt this conclusion, however, because it is based on a bad analogy.  I have direct experience of a human mind through my subjective experience of my mind.  But I have no such experience of a divine mind.)

Some evolutionary psychologists have recently been converging on an evolutionary explanation of religious belief that might support Plantinga's insight, because they are uncovering a deep, evolutionary link between believing in other minds and believing in God. But while some of these Darwinian psychologists (such as Justin Barrett) see this as showing that Darwinian science is compatible with the truth of believing in God, others (such as Jesse Bering) see this as exposing belief in God as a fictional construction of the evolved human mind. For those like Barrett, religious belief is an adaptive truth. For those like Bering, religious belief is an adaptive illusion.

In contrast to both Barrett and Bering, some evolutionary theorists (like Richard Dawkins) argue that religious belief is not an evolutionary adaptation at all, but rather a byproduct of our having evolved big brains that are capable of big mistakes.

Barrett lays out his position in his book Why Would Anyone Believe in God?, which I have taken up in a previous post.

Bering has summarized his position in a new book--The Belief Instinct: The Psychology of Souls, Destiny, and the Meaning of Life (2011). Bering has posted a brief excerpt from this book as an essay for Slate.

Bering builds upon the "social brain" hypothesis of Robin Dunbar and others--the idea that the big brains of primates can best be explained as evolutionary adaptations to the social complexity of primate life. The unique complexity of human social life is correlated with the unique complexity of the human mind.

Navigating our way through the intricacies of human social life requires that we have a "theory of mind"--that we be able to read the minds of other individuals as intentional agents whose actions are governed by their beliefs, desires, and goals. This is difficult, because while we have direct, subjective awareness of our own minds, we have no experience of other minds. We must project our own subjective experience onto others and infer that they are intentional agents like us.

Although there continues to be debate as to whether there is any evidence for chimpanzees or other apes having some capacity for a theory of mind, it is clear that human beings are uniquely good at reading the minds of others. There is some evidence that human infants as early as 9-months old begin to understand adults as intentional agents, and they do this in a way that far surpasses what the chimps can do.

This human capacity for mind-reading is probably rooted in the development of the human brain--particularly, the prefrontal cortex--as suggested by some brain imaging studies. Further evidence for this is that autistic people and others who show deficits in their mind-reading abilities are probably suffering from impairment in those parts of the brain necessary for interpreting the subtle cues of intentional agency in others.

Because we have such a powerful neural system for mind-reading, we are easily inclined to see minds everywhere, even in nonliving objects. In the famous experiment conducted by Fritz Heider and Mary-Ann Simmel, the viewers of a film showing geometric figures in motion thought they saw a large triangle "bullying" a "timid" small triangle to steal the affections of a "female" circle.

Similarly, Bering argues, our instinctive theory of mind inclines us to see supernatural minds at work in the universe. Thus, our belief in God's mind is just our overactive theory of mind.

Bering contends that this evolved human instinct for mind reading is responsible for four kinds of illusions--superhuman purpose, superhuman signs, a superhuman afterlife, and superhuman morality.

Our belief in superhuman purpose comes from our projecting mental agency onto the cosmos. We ask about the purpose of life, as if life must be the artificial product of a plan by an intelligent agent with some purpose in mind. Even atheists commonly have some sense of destiny, some vague belief that their life has a purpose.

But if we accept the theory of evolution, Bering insists, then this belief in the purpose of life is a cognitive illusion. We don't have a purpose in life, we simply are. Life has no purpose, it simply is. But our mindlessly evolved theory of mind makes it almost impossible for us to believe that there is no mindful purpose to life.

Our belief in superhuman signs comes from our instinctive inclination to look for hidden messages in natural events as controlled by invisible intelligent agents. It is not enough to know how things happen, because we want to know why they happen. We look for the meaning in things. Consequently, much of religious experience consists in interpreting the supernatural messages in the natural world coming from dead ancestors, spirits, angels, or gods. Even modern scientists continue the tradition of natural theology in considering how the divine order is manifest in nature.

Our belief in a superhuman afterlife comes from our inability to imagine what it would feel like to be dead. We cannot prove to ourselves that we are mortal, because we cannot be conscious of being dead. Thus, as Goethe said, "everyone carries the proof of his own immortality within himself."

Sigmund Freud explained the belief in an afterlife as wish fulfillment, and therefore as an expression of our fear of death. But Bering argues that this wish-fulfillment theory doesn't account for the illusion. We have lots of wishes that we don't assume to be true. So why is the wish to be immortal so easy to believe? It must be because it matches our instinctive intuitions about the continuity of the mind after death, which we can see in the beliefs of young children.

Our belief in supernatural morality comes from our evolved social psychology of morality. We look for people to blame for our suffering. When we can't blame another person, we look for some invisible intentional agent to give meaning to the suffering.

It's not enough for us to know how bad things happen to good people. We want to know why they happen, which implies that everything is ordered by some cosmic mind with a moral purpose. This natural propensity of the human mind to look for a cosmic moral order is so strong, Bering indicates, that even most atheists (according to some psychological studies) believe that "everything happens for a reason."

Bering's evolutionary explanation for this is that human social cooperation requires that we be intensely sensitive to the opinions of others--we care about what others think of us, and this concern for our reputation gives us the incentive for good behavior. That's why gossip is such a powerful tool for enforcing good conduct and punishing bad conduct. This requires a theory of mind by which we see ourselves through the eyes of others.

If we think others are not looking, we are tempted to cheat. But if we think there are supernatural agents always watching us, then we are less tempted to cheat. Believing in supernatural moral spectators would protect us from doing the things that ruin our reputations, and this would be favored by natural selection.

Of course, Bering recognizes, the doctrinal and ritualistic content of religious belief is set by cultural traditions that vary across history and across societies. But underlying this cultural diversity is a basic cognitive illusion that is universal. Bering writes:

By all accounts, the basic illusion of God (or some other supernatural agent) "willfully" creating us as individuals, "wanting" us to behave in particular ways, "observing" and "knowing" about our otherwise private actions, "communicating" His desires to us in code through natural events, and "intending" to meet us after we die is pretty convincing for most people. (195)

And yet, how does Bering know that this is an adaptive illusion rather than an adaptive truth? He admits that his evolutionary account of religion as rooted in an evolved theory of mind cannot disprove the existence of God. After all, evolutionary psychologists like Justin Barrett defend this evolutionary account, while seeing it as perfectly compatible with believing that God allowed human beings to have this naturally evolved theory of mind so that they could discover Him.

Bering agrees with Barrett that science by itself can neither prove nor disprove the existence of God. But still, Bering insists, science can conclude that God's existence is highly improbable. Barrett finds Plantinga's argument plausible: "if my belief in other minds is rational, so is my belief in God." And yet, Bering finds this sort of reasoning silly. Plantinga assumes that believing in the existence of other human minds is comparable to believing in the existence of God's mind. But this is clearly not true. Dealing with other human minds is part of our ordinary human experience. Dealing with God's mind is not.

Bering doesn't realize that this debate has a long philosophical history--from Plato to Cicero to Hume. From Plato's Laws (Book 10) and his Phaedo, we know that Plato understood that the most appealing ground for believing in the divine was to project our experience of mental agency onto the universe, but there are good reasons to doubt the plausibility of such reasoning, as suggested by Cicero--in On the Nature of the Gods--and Hume--in Dialogues Concerning Natural Religion. Although we are innately inclined to see an analogy between human minds and divine minds, it is not clear that the analogy is strong enough to justify religious belief.

Bering doesn't realize that most of what he says about the evolution of religious belief follows the lines of Darwin's reasoning in the DESCENT OF MAN (Penguin Classics, 2004). Darwin saw that "belief in unseen or spiritual agencies" was universal among primitive human beings, and that this probably arose first "when anything which manifested power or movement is thought to be endowed with some form of life, and with mental faculties analogous to our own" (116-117). "The belief in spiritual agencies would easily pass into the belief in the existence of one or more gods. For savages would naturally attribute to spirits the same passions, the same love of vengeance or simplest form of justice, and the same affections which they themselves feel" (118).

Only by deeper rational reflection and observation do we realize that all the order we see in the world does not have to be the product of intelligent and intentional design. As Cicero and Hume suggested, human intelligent design is not the only possible source of order that we observe in the world. For example, in the growth of plants from seeds, we see order arising by nature without mental agency. Furthermore, thinkers like Cicero and Hume recognized the possibility of evolutionary order through the selective retention of heritable traits that enhance survival and reproduction, which can create spontaneous orders that are not intelligently designed by any mind or group of minds.

In the philosophic tradition of Plato, Cicero, and Hume, we can see a deeper question at issue here that Bering passes over quickly without much thought. Can we--or should we--free ourselves of the "adaptive illusion of God"?

On the one hand, Bering seems to think we can't do this. He writes:

It is therefore more than a little foolhardy to think that human nature can ever be "cured" of God by scientific reason. As a way of thinking, God is an inherent part of our natural cognitive systems, and ridding ourselves of Him--really, thoroughly, permanently removing Him from our heads--would require a neurosurgeon, not a science teacher. (200)

On the other hand, Bering rejoices that for the first time in human history, we find ourselves "in the full godless light of this shattered illusion." He admits that this might be detrimental to our moral life, if in fact, we need religious belief to support our morality. But then he concludes: "With or without belief, the consequences for acting selfishly are as much a deterrent as they've always been: those who don't play by the rules will--by and large, more often than not--suffer the human consequences" (201-202).

Plato, Cicero, and Hume would agree that moral order can be based on human nature, human custom, and human judgment, without any religious support. But they also suggested that for many, if not most, human beings, religious belief provides a necessary reinforcement for moral conduct. Darwin suggested the same conclusion in his account of the natural moral sense, in which morality can stand on its own natural ground, even without religious sanction, although religious belief can provide powerful reinforcement for our natural morality.

Some of the political founders of modern liberal republicanism understood this. For example, George Washington, in his Farewell Address, observed:

Of all the dispositions and habits which lead to political prosperity, religion and morality are indispensable supports. In vain would that man claim the tribute of patriotism who should labor to subvert these great pillars of human happiness--these firmest props of the duties of men and citizens. The mere politician, equally with the pious man, ought to respect and to cherish them. A volume could not trace all their connections with private and public felicity. Let it simply be asked, Where is the security for property, for reputation, for life, if the sense of religious obligation desert the oaths which are the instruments of investigation in courts of justice? And let us with caution indulge the supposition that morality can be maintained without religion. Whatever may be conceded to the influence of refined education on minds of peculiar structure, reason and experience both forbid us to expect that national morality can prevail in exclusion of religious principle.

Notice that Washington intimates that "the influence of refined education on minds of peculiar structure" can produce good behavior without religious belief. But "reason and experience" should tell us that most human beings need religious belief as a support for their morality.

Washington helped to establish a new government without a governmental establishment of religion, but one which would secure the free exercise of religion. Doesn't this indicate the best political resolution of this debate between reason and revelation?

If the religious belief supporting morality really is rooted in our evolved theory of mind, then we can rely on it to arise by spontaneous order in any civil society with religious liberty. At the same time, those few who live "in the full godless light of this shattered illusion" can be guided by the moral norms rooted in human nature, human culture, and human judgment.

In a free society, people like Jesse Bering and Justin Barrett can live together, being united by their scientific inquiry into human nature, while being free to disagree as to whether the final ground of explanation is to be found in nature or in nature's God.

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

The MPS in the Galapagos (14): The Evolution of Religious Belief

Originally, Pascal Boyer was to lecture at the MPS conference on the evolution of religious belief.  He teaches in the Departments of Psychology and Anthropology at Washington University in St. Louis.  In one short summary of his evolutionary theory of religion, he concludes: "The mind has myriad distinct belief networks that contribute to making religious claims quite natural to many people."

Unfortunately, Boyer lost his passport, and so he could not travel to the Galapagos.  Leda Cosmides agreed to speak in his place, followed by Father Robert Sirico, the founder of the Acton Institute for the Study of Religion and Liberty.

Cosmides began by suggesting that Boyer's evolutionary account of religious belief is a Hayekian view of how ideas spread--those that are more successful in conforming to the human mind tend to prevail.  Boyer explains how ideas about the supernatural arise as byproducts of normal cognitive functioning.

According to evolutionary psychologists, the human brain has evolved cognitive functions for detecting intelligent agency and human artifacts, and consequently the brain is naturally inclined to find intelligent agency in whatever looks like it was intentionally designed.  This makes it easy for us to belief in supernatural agents.

Cosmides insisted that this theory of the cognitive evolution of religious belief remains neutral on the issue of whether God exists.

To support this, she could have mentioned the work of Jesse Bering and Justin Barrett.  As I have indicated in some previous posts here and here, Bering and Barrett agree in accepting the evolutionary origin of religious belief.  But while Bering is an atheist, Barrett is a Christian.  A Christian psychologist like Barrett can believe that human beings have a naturally evolved inclination to believe in God, because God has created them that way, using an evolutionary process.  By contrast, an atheist like Bering can see the evolutionary explanation of religious belief as showing that such belief is an illusion.

Following Cosmides, Father Sirico spoke on "Hayekian Social Theory and Religious Truth."  His main idea is conveyed in the last two sentences: "The battle to see the religious mind as an integral part of the social process is part of the same battle to regard the freedom of the marketplace through which economic knowledge develops and which must be allowed to work itself out without the intervention of 'scientists' who purport to have more knowledge than the human experience itself can provide.  However implausible it may seem, the development of society and the development of faith have more in common than might be first supposed" (18-19).

While wondering why Hayek's writing shows so little overt discussion of religion, Father Sirico argued that Hayek's understanding of social order as emerging best through spontaneous evolution is applicable to the evolution of religious belief.  He made three points in support of this claim.

First, he noted how often Hayek cited religious thinkers like Lord Acton and the late scholastics of the middle ages, who supported the idea of social order as the "result of human action but not of human design."

Second, Father Sirico argued that Hayek's condemnation of rationalist constructivism and scientism could apply to the rationalism of the "New Atheists," who try to dispose of all inherited religious beliefs and then reconstruct all our beliefs as personal constructions of reason.

Third, he argued that Hayek's account of how social order arises from a gradual evolutionary development could also apply to the development of religious doctrine.  The doctrines of Christianity arose through many centuries of experience as an evolutionary process of adaptation and refinement.  He found this best expressed in some of the writing of John Henry Newman.

Father Sirico's most interesting thought on this third point was how religious fundamentalism took a constructivist approach similar to socialism.

As I listened to Father Sirico, I wondered whether Boyer would agree with him that religious belief arises from the social marketplace, in which some religious beliefs by trial and error are found to be better adapted to the human mind than are others.  This seemed to be what Cosmides meant when she said that Boyer's evolutionary explanation of religious belief was Hayekian.

In the question and answer period after the two lectures, I asked this question: Do the two of you agree that atheism is contrary to evolved human nature?

They both said yes.  Cosmides said that atheism is not naturally adapted to evolved mental capacities.  She also indicated that she disagrees with Richard Dawkins in his aggressive attacks on religion.

Father Sirico said that the methodological naturalism of many scientists is contrary to natural human experience.

During this discussion period, Father Sirico objected to Hayek's social evolution as lacking a telos.  He said that we need a standard in human nature to set the telos for judging cultural traditions.  He used the example of the multiculturalist support for female circumcision (or genital mutilation) as showing the stupidity of cultural relativism without a natural standard of judgment.

I agree with this.  I would say that there is an immanent telos in human evolution insofar as the 20 natural desires of evolved human nature set a standard by which we can judge societies as better or worse in satisfying those natural desire, including the natural desire for religious understanding.

In some previous posts, I have used the example of female circumcision to illustrate this, just as Father Sirico did.  This is what I mean by "Darwinian natural right."

These lectures concluded the Mont Pelerin Society conference in the Galapagos on "Evolution, the Human Sciences, and Liberty."  As you can see by my 14 blog posts, this was a remarkably stimulating conference in helping me think about the moral, economic, political, and religious implications of Darwinian evolutionary science.  Combined with my "evolutionary tour of the Galapagos" during the preceding week,  this gave me much to ponder as I continue to develop my argument for Darwinian liberalism.

A Thousand Posts (2)

2009
In January, my post on "Evolutionary Psychology's Slow Acceptance of Darwinian Morality" pointed to the most important turn in the recent history of evolutionary psychology--the acceptance of Darwin's evolutionary theory of morality in The Descent of Man. 

In his famous lecture on "Evolution and Ethics" in 1893, Thomas Huxley adopted a Kantian transcendentalist view of ethics and invoked the is/ought dichotomy in rejecting Darwin's claim that the evolutionary explanation of morality was part of the evolutionary science of human nature.  For over a century after Huxley's lecture, most Darwinian biologists--including George Williams and Richard Dawkins--agreed with Huxley's rejection of Darwin's evolutionary ethics.  Therefore, they were disturbed by Ed Wilson's efforts--in Sociobiology (1975) and Consilience (1998)--to revive Darwin's evolutionary study of morality.  In the 1980s and 1990s, I had argued in agreement with Darwin and Wilson, but my argument was scorned by the leaders of evolutionary psychology.  Remarkably, however, by 2009, the tide had turned as the growing research on the evolutionary psychology of morality confirmed that Darwin was right after all.  One of the leaders of this movement was Jonathan Haidt.  I wrote my first post on Haidt's research in November of 2009.  I returned to Haidt in September of 2012 and October of 2016.  In January of 2011, I wrote a post on how Sam Harris had persuaded Richard Dawkins to change his mind and accept Darwinian ethics.

An evolutionary moral psychology assumes the reality of an evolved human nature.  But my colleague at Northern Illinois University--David Buller--has dismissed the idea of human nature as a superstition in his book Adapting Minds, which is a general critique of evolutionary psychology.  In January, I wrote a post arguing that Buller's denial of human nature depends on a silly definition of human nature as consisting only of traits that satisfy three conditions--first, they must be unique to human beings and thus not shared with any other animals; second, they must be invariably and exactly the same for all human individuals everywhere; and, third, they must be eternal essences that are not historically contingent.  It is easy for Buller to argue that human evolution has not produced a human species with such traits. But a sensible definition of human nature does not require these conditions. We could define human nature as constituted by regularities in that suite of generally recurrent anatomical, physiological, and psychological traits that characterize the human species.  These regularities do not have to be uniquely human, invariably the same for all individuals, or eternal essences.  These regularities of human nature include what I have identified as the 20 natural desires.

I elaborated some of these points in April in posts on nature and human nature and on Marjorie Grene's account of natural teleology and the concept of species.  In September, I defended the Aristotelian and Darwinian understanding of species.

In the spring, I taught a graduate seminar on David Hume. In May, I wrote a long post on "A Research Program for a Humean Science of Human Nature."  In his Treatise of Human Nature, Hume laid out his grand vision of a comprehensive science grounded on a science of human nature.  Every topic that I have taken up on this blog could be understood as part of this Humean science of human nature rooted in Darwinian evolutionary science. This science could be sketched out according to at least ten broad themes running through my blog posts: (1) Darwinian liberal education, (2) deep history, (3) ethology, (4) behavioral game theory, (5) neuroscience, (6) social history, (7) moral psychology, (8) evolution of religion, (9) evolutionary aesthetics, and (10) the Darwinian future of human nature.

In May and June, I travelled around England and Scotland, and I wrote a series of posts on the natural history of Great Britain based on my travels.  During this trip, I visited Darwin's house in Down and wrote some posts on that.  As I indicated, some of my first reading of Darwin included the notebooks that he began writing after he returned to England from his trip on the Beagle.  I was impressed with those notebooks as showing Darwin's mind at work, and my writing of this blog is in some ways following the style of Darwin's writing in his notebooks.

My visit to Darwin's house and reading about his family life led me to write about how Darwin's pondering the suffering and death of his daughter Annie manifested his understanding of love and death.  I wrote this in response to Peter Lawler's assertion that Darwin advanced an "impersonal theory of evolution" denying the personal reality of love and death.

From the end of June to the end of September, I wrote many posts on the history and philosophy of Platonic moral cosmology, in which I set up a debate between Remi Brague and C. S. Lewis, on one side, and Catherine Zuckert and Joseph Cropsey, on the other.  Brague and Lewis see Plato's dialogues (particularly the Timaeus and book 10 of The Laws) as defending a divinely designed teleological cosmology as setting the cosmic standards for the moral and political life of human beings, but they also see this Platonic moral cosmology as overturned by modern science (including Darwinism) in a way that promotes moral nihilism by teaching that the cosmos is indifferent or even hostile to human concerns.  By contrast, Zuckert and Cropsey see Plato's Socrates as denying, or at least questioning, that moral cosmology taught by Timaeus and the Athenian stranger, and suggesting that instead of finding moral guidance in the cosmos, humans need to look to their own human wants and desires.  Even if the cosmos does not care about or for us, we care about and for ourselves.  This Socrates identified by Zuckert and Cropsey belongs to a tradition of Socratic skepticism that includes Cicero, Hume, and Darwin.

If Zuckert and Cropsey have the correct interpretation of Socrates' position, then Socrates is close to my position--that human morality and politics depend not on a cosmic teleology but on an immanent teleology of human natural desires.  If human beings are by their natural desires directed to certain ends or purposes, then we can see those ends or purposes as intrinsic to their nature, regardless of whether those ends or purposes have any cosmic reference.  Darwinian biology supports such an immanent teleology because it recognizes the goal-directed behavior characteristic of various animal species, including the human species.

While some Straussians like Zuckert and Cropsey reject Platonic cosmic teleology as false, others insist that it needs to be supported as at least a "noble lie" that sustains popular conceptions of natural right, and that the Darwinian denial of cosmic teleology is (as Nietzsche put it) "true but deadly."

In September, I endorsed the "Midwest Straussianism" promoted by Catherine and Michael Zuckert.  The Straussians seem to have affirmed three propositions that are contradictory: 1. America is modern. 2. Modernity is bad. 3. America is good.  To overcome the contradiction, the West-Coast Straussians have denied #1, the East-Coast Straussians have denied #3, and the Midwest Straussians have denied #2.  I agree with the Midwest Straussians that modernity is good, and for me this includes not only modern political thought, but also modern natural science.

From October to December, I wrote many posts on the evolutionary biology of human rights as rooted in evolved human nature, and in doing so, I argued that the idea of human rights does not depend on any religious belief in the creation of human beings in the image of God.  As part of this discussion, I wrote about the debate over female genital mutilation as a violation of human rights.

2010
In January, I travelled to England to direct a week-long seminar at Oxford University on "Evolution and Ethics."  The participants were mostly philosophy professors and students from China.  In October, we met again in China (Beijing) for a conference to present papers coming out of the seminar.  This led to a series of posts on the evolutionary psychology of ethics.

As I anticipated, much of the discussion at the seminar turned on the debate between the Platonic or transcendentalist view of ethics and the Humean or empiricist view. A Darwinian evolutionary understanding of ethics is on the side of the Humean view that sees ethics as rooted in human nature, particularly in human emotions, beliefs, and desires. On the other side, the Platonic view taken by those like Kant looks to a transcendent conception of the Good that is somehow woven into the order of the cosmos. (As I have indicated in various posts, the careful reader of the Platonic dialogues might doubt whether Plato himself--or Plato's Socrates--was a Platonist in this way.)

A growing number of leading philosophers today are adopting a Humean/Darwinian moral psychology supported by recent research in evolutionary science, neuroscience, anthropology, and animal behavior. But one can still see the powerful influence of a Kantian transcendentalism in moral philosophy that regards morality as an autonomous realm of pure reason totally separated from the empirical realm of nature as studied by natural science.

Kantian philosophers like Richard Joyce worry that evolutionary ethics promotes moral nihilism by teaching that morality is fictional. Joyce agrees with Kant that by definition moral judgments presuppose belief in a transcendent world of moral facts beyond the empirical world of natural facts. But since he denies the truth of that belief, because there really are no such moral facts, he concludes that we cannot know that morality is true, and therefore we cannot know that moral rightness and wrongness really exist. Moreover, he argues that evolutionary ethics necessarily leads us to this conclusion that morality is fictional, because an evolutionary account of morality explains it as arising from the natural facts of human desires and capacities without any reference to any distinctively moral facts.

I agree that believing in a moral law grounded in divine will or transcendent reason might strengthen the moral motivation of people with such a belief. But it seems clear to me that people can still have a strong motivation for moral conduct when they believe that morality has no other ground than the evolved human nature of our moral emotions.

That a Kantian philosophical idealism does not necessarily support good moral judgment is indicated by the fact that most of the German philosophers who supported Nazism were Kantian idealists. For me, as I indicated in a post in January, this suggests that the evils of Nazism flowed from a metaphysical tradition of idealist utopian philosophy that stretches from Plato to Fichte to Nietzsche to Heidegger.

My reasoning for rejecting Kantian categorical normativity is clarified in my post on "Philippa Foot and the Hypothetical Imperatives of Natural Goodness" (March).

In 2010, I wrote a lot about the natural evolution of religious belief.  I have identified the desire for religious understanding as one of the twenty natural desires rooted in our evolved human nature. Human beings generally desire to understand the world as governed by gods or God, because this satisfies their natural longing to make sense of things that would otherwise be incomprehensible.

The recent research on the evolutionary and cognitive causes of religious belief goes a long way to substantiate my position. The general reasoning for how religious belief evolved as an innate disposition of human nature is laid out by David Hume and Charles Darwin. This new research provides elaborate theoretical and empirical grounds for their naturalistic account of religion.

One of the proponents of this research is Justin Barrett, whom I met at the Oxford seminar. He is an evolutionary psychologist who argues that the evolved propensity of the human mind to detect intelligent agents supports a natural tendency to believe in divine agents. Barrett is a Christian evolutionist.  His work largely confirms what Hume says in his Natural History of Religion. Barrett is a Christian who sees his evolutionary explanation of religious belief as compatible with his own Christian belief that God has created human beings so that they can discover him.  I have also written about Jesse Bering (in February of 2011), who explains the evolutionary psychology of religious belief in a way similar to Barrett's explanation, but Bering is an atheist.

Also in 2010, I wrote about Rebecca Goldstein's philosophical novel on the "36 arguments for the existence of God" (February), the evolution of Heaven and Hell (April-May), the evolutionary game theory of how religion supports cooperation (April), and Confucianism (June, August, October).  My writing on Confucianism was drawn from my paper on Darwinian and Confucian Ethics for the conference on "Evolution and Ethics" in Beijing in October, which included some of the same Chinese professors and students who were at the Oxford conference in January.

Religious belief is uniquely human because it arises from the uniquely human capacity for symbolic thought and communication that allows human beings to construct a shared imagined reality.  In February, I wrote about how Eva Jablonka and Marion Lamb have explained human symbolism as one of four dimensions of evolutionary inheritance: genetic, epigenetic, behavioral, and symbolic.  Recognizing these four levels of evolution helps to explain the "animal culture wars" (April): if "culture" is defined as inherited behavioral traditions, then some nonhuman animals have culture; but if "culture" is defined as inherited symbolic traditions (like religious belief), then this is uniquely human.

In 2010, I wrote a lot about Aristotelianism.  In March and April, I wrote a series of posts on Douglas Rasmussen and Douglas Den Uyl's Aristotelian liberalism and showed how a Darwinian moral and political psychology supported this.  In the fall, I was teaching a graduate seminar on Aristotle, and I wrote some posts in September, October, and December, on "Aristotle's Darwinian Ethics," which went into my paper on "The Darwinian Science of Aristotelian Virtue" for the conference on "Science and Virtue" organized by Peter Lawler and Marc Guerra at Berry College (Mount Berry, Georgia) in November.  In 2013, the papers for this conference were published in The Science of Modern Virtue: On Descartes, Darwin, and Locke, edited by Lawler and Guerra (NIU Press).

In July, I pointed to my essay for "Cato Unbound" on "Darwinian Liberalism," which would lead to papers and lectures in later years on the Darwinian psychology of classical liberalism.

My list of 20 natural desires includes the natural desire for courage in war, because human beings generally desire war when they think it will advance their group in conflicts with outside groups.  The is the one desire that has provoked the most criticism from people who are uncomfortable with the idea that war might be rooted in evolved human nature.  In 2010, I began to write the evolutionary psychology of war in various posts (in February, June, and December).  I returned to this issue in 2011, in response to the publication of Steven Pinker's The Better Angels of Our Nature.

Also, in 2010, I began writing about anarchism (June) and equality in the Lockean state of nature (July), and I would return to these topics in subsequent years.

To be continued . . .

The Darwinian Lockean Liberalism of Natural Religion

In this season of the year, our greetings of "Merry Christmas" and "Happy Holidays" acknowledge our natural human propensity to religious beliefs and rituals, while also acknowledging that in the modern liberal social orders in which many of us live today, we respect religious liberty and toleration.  "Merry Christmas" doesn't favor any one Christian tradition over any other.  And "Happy Holy Days" recognizes that there are some non-Christian religious observances during this season--particularly, the Jewish festival of Hanukkah.

The Darwinian Lockean Liberalism that I have defended explains the naturalness of religion as rooted in our evolved human nature.  It also explains why we need religious liberty and toleration so that all individuals have the equal liberty to pursue their natural desire for religious experience in their own way.

My position has provoked lots of criticisms, of which two are most prominent.  The first is that Darwinian Lockean Liberalism is incoherent insofar as Darwinian atheism denies the Christian foundations of Lockean Liberalism.  The second is that Lockean religious liberty and toleration denies the truth of Christian Integralism (Catholic or Protestant) that there is one true church--the true Christian Church established by Jesus Christ--and that this Christian Church can rightly use the secular authority of government to enforce the Orthodoxy of that Church.

I have previously responded to these two criticisms (here and here).  But after thinking more about these issues, I have decided to lay out a slightly revised version of my previous responses.

Various authors have countered my position with a syllogistic rebuttal (Dilley, 2013; Holloway, 2006; West, 2006).  I will call this “Dilley’s Syllogism” because Stephen Dilley formulated it in his Introduction to his edited book Darwinian Evolution and Classical Liberalism:

Classical (Lockean) liberalism is founded on Christianity.

Darwinism denies Christianity.

Therefore, Darwinism denies classical (Lockean) liberalism.

The conclusion of this syllogism is false, because the major premise is only partly true, and the minor premise is totally false.

The major premise has been asserted by those of my critics who are proponents of what they call “Christian classical liberalism” or “theistic classical liberalism” (Dilley, 2013, pp. 19, 23, 158-59).  I have inserted “Lockean” into the syllogism because these critics generally appeal to Locke as “the quintessential classical liberal” (Dilley, 2013, p. 198).  The only doctrinal teaching of Christianity that they mention as supporting Lockean classical liberalism is the idea of imago Dei: that all human beings have been created in the image of God (as declared in Genesis 1:26-27) seems to endow them with the equal moral dignity that supports the classical liberal teaching that all human beings are created equal in their moral dignity as equally endowed by God with natural rights (Dilley, 2013, p. 11). 

Locke seemed to adopt this idea in speaking about the law of nature as grounded in the nature of human beings as God’s “workmanship”:

Reason, which is that Law, teaches all Mankind, who will but 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 another’s Pleasure (ST, 6).

Locke identified this idea of men being God’s property because they are his workmanship with man being created in God’s image, in the sense that all members of the human species were created as “intellectual creatures,” which gave them dominion over the “inferior creatures,” but without giving any human being dominion over any other human being, because all men were equal in having a human mind that was a likeness to the Mind of God (FT, 30, 39, 52-54, 85-86; ST, 56).

But Locke also claimed that natural rights were rooted in every man’s self-ownership (ST, 27).  Now, as Peter Laslett (1970, p. 100) observed, this principle of human self-ownership “almost contradicts his principle that men belong to God, not themselves.”  “Almost”?  Can men both belong to themselves and belong to God?  I have argued that evolutionary neuroscience can explain the human experience of self-ownership as rooted in the interoceptive capacity of the embodied brain.  But the human experience of being owned by God might be harder to explain scientifically.

The apparent contradiction between Locke’s principle of self-ownership and his principle of divine ownership can be resolved by seeing that Locke made what Michael Zuckert has called a “two-track argument,” in which “one track is theistic, the workmanship argument, an argument of natural theology; the other track is the appeal to self-ownership” (Zuckert, 2002, pp. 4-5; 2005, p. 431).  Locke believed that the workmanship argument would require a rational theology that could prove the existence of God.  From “the idea of ourselves as understanding, rational creatures,” we would have to infer “the idea of a supreme Being, infinite in power, goodness, and wisdom, whose workmanship we are” (ECHU, IV.3.18).  Through an anthropomorphic analogy, we could project from the idea of our own minds and other human minds the idea of a Divine Mind.  Thus, man would create God in man’s image (ECHU, IV.3.27; IV.10.1).  But then Locke admitted that having the idea of God in one’s mind does not prove God’s real existence (ECHU, IV.10.7; IV.10.19; IV.11.1).

Since he doubted that reason could prove God’s existence in support of the workmanship argument, Locke developed the self-ownership argument that would provide a purely natural ground for his law of nature.  He wanted to appeal to a rational theology of divine workmanship, but if that failed, he could fall back onto his natural self-ownership argument.  These two tracks—God and nature--are suggested by Locke’s repeated appeals to “the Laws of God and Nature” (FT, 56, 124; ST, 60, 66, 90, 93, 142, 195).  The “fixed and permanent rule of morals” could be “firmly rooted in the soil of human nature,” and human nature could be understood as created by “nature or God” (1997, p. 125).  Notice that the creative source of human nature is nature or God.

Consequently, the major premise of Dilley’s Syllogism is only partly true.  Yes, Locke’s classical liberalism can be grounded in the Christian doctrine of creation in the image of God as supporting the workmanship argument.  But Locke suggested that reason can neither prove nor disprove creationist theology.  And that led him to appeal to the self-ownership principle as a purely naturalistic argument that did not require any theological assumptions.  Another way of saying this is that Locke left the Reason/Revelation debate open, believing that neither side can refute the other.  And so, he often invited his readers to consider both what “Reason” taught them by their natural experience and what “Revelation” taught them through their reading of the Bible (ST, 25).

The minor premise of Dilley’s Syllogism—Darwinism denies Christianity—assumes that the Darwinian scientist believes that scientific reason can refute Christian revelation and thus supports atheism.  But even if this is true for some Darwinian scientists, it is not true for all--not even for Darwin himself.  Moreover, Darwinian evolutionary science recognizes that there is a natural desire for religious understanding, and so atheism is contrary to our evolved human nature.  But even though religious belief is natural for most human beings, what they believe about the supernatural will be determined by faith rather than reason.  And since religious believers can never reach agreement about the content of their faith, they must accept the fact of religious pluralism and recognize how that religious pluralism dictates the religious toleration that secures religious liberty.

Of course, there are Darwinian atheists.  Richard Dawkins, for example, has said that “I could not imagine being an atheist at any time before 1859, when Darwin’s Origin of Species was published.”  He thinks the Argument from Design has always been the best of the arguments for the existence of God, because the complexity of the living world appears to be the work of an intelligent designer—just as William Paley’s watch implied the existence of a watchmaker—and so we might infer that God is the Intelligent Designer of the living world.  David Hume rightly criticized this reasoning as illogical because it rests on a false analogy between human intelligent design and divine intelligent design.  We have all seen human intelligent designers at work as part of our ordinary human experience.  But we have never seen a Divine Intelligent Designer creating everything out of nothing.  This is not part of our ordinary human experience.  It is fallacious, therefore, to use apparent design in nature as evidence for the existence of God.  But even if Hume was right about this, Dawkins has observed, Hume did not offer any alternative explanation for apparent design in nature.  It was only in 1859, when Darwin showed how evolution by natural selection could explain complex biological design, that “Darwin made it possible to be an intellectually fulfilled atheist” (Dawkins, 1986, pp. 5-6).

And yet Darwin himself denied that his theory of evolution promoted atheism.  Consider what he said about “the Creator” in the last two paragraphs of The Origin of Species.  He rejected the common “view that each species has been independently created,” and he proposed instead that “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.”  Then, in his famous last sentence, he spoke of the “grandeur in this view of life, with its several powers, having been originally breathed by the Creator into a few forms or into one,” and that “from so simple a beginning endless forms most beautiful and most wonderful have been, and are being evolved” (1936, pp. 373-74).

Here we see that Darwin adopted the medieval Scholastic metaphysics of “dual causality” in distinguishing supernatural primary causes and natural secondary causes (Maurer, 2004).  The Creator did not miraculously create each species of life separately.  But He did originally exercise primary causality in impressing the laws of nature on matter and breathing life into a few forms or into one.  Then, from that simple beginning, the Creator allowed all the forms of life to emerge through the secondary causes of the natural evolutionary process.

At this point in his life, Darwin was what today we would call a “theistic evolutionist” or “evolutionary creationist”—someone who believes that the existence of God as the Creator is compatible with evolutionary science.  Indeed, Darwin said that it was “absurd to doubt that a man may be an ardent Theist and an evolutionist.”  And even when, towards the end of his life, he became an agnostic, he insisted: “In my most extreme fluctuations, I have never been an atheist in the sense of denying the existence of God” (1879; 1969, pp. 92-96). 

In the creation/evolution debate among Christians today, many Christian thinkers—such as Francis Collins, Deborah Haarsma, Darrel Falk, Alvin Plantinga, and Justin Barrett—have defended evolutionary creationism in arguing that, just as Darwin said, one can be both a theist and an evolutionist (Collins, 2006; Stump, 2007).  Remarkably, even the “young-Earth creationists,” who believe in the literal six-days-creation story in Genesis and a 6,000-year-old Earth, concede that Darwin’s Origin of Species refuted the traditional belief that God specially created all species of life, because they agree that all species emerged through evolution by natural selection.  But they also insist that God had to specially create all the “kinds” of animals and plants, so that the evolution of species could unfold within the limits of those “kinds” (with “kinds” corresponding to the taxonomic level of “families”) (Wood, 2008, 2011; Wood and Murray, 2003; Ham, 2017, pp. 14-26).   This resembles what Darwin said about the Creator breathing life into “a few forms or into one,” from which all species could then evolve by natural selection.

Darwin and the evolutionary creationists agree with Locke that religious belief is natural for human beings because they are naturally inclined to infer from their knowledge of their own minds and the minds of others that there must be a divine mind that exercises a supernatural intelligent agency analogous to the natural intelligent agency of human minds.  Darwin observed that when “conceiving this immense and wonderful universe, including man with his capacity of looking far backwards and far into futurity,” he “felt compelled to look to a First Cause having an intelligent mind in some degree analogous to that of man,” which made him a theist (1969, pp. 92-93).  

Similarly, some evolutionary psychologists—such as Justin Barrett and Jesse Bering--have argued that the natural evolution of religious belief is rooted in the propensity of the human mind to detect rational agency in humans and other animals and then to infer a supernatural intelligent agency analogous to that of human minds (Barret, 2004; Bering, 2011).  But as we have seen, this anthropomorphic analogy between human and divine minds is dubious, and even if this explained the natural evolution of the idea of God in the human mind, that would not prove the existence of God.

This led Locke to conclude that believing in the existence of God is ultimately not a matter of reason but of faith.  And since “faith is not knowledge,” we cannot know what the true religion is (Locke, 1870, pp. 94-96; 1997, pp. 248-50; ECHU, IV.17-18).  Consequently, political rulers cannot coercively enforce belief in the religious orthodoxy of the true church, because religious believers cannot agree on what that orthodoxy is.  “Every man is orthodox to himself,” Locke observed in the Letter Concerning Toleration.  And “every church is orthodox to itself” (2010, pp. 7, 21, 38).  The simple fact of religious pluralism—that religious believers cannot agree on religious orthodoxy—supports Locke’s liberal argument for religious liberty and toleration of all religious sects that inflict no injury on others.  Religious liberty and religious pluralism create a free marketplace of religion in which religious movements must compete for adherents.  Those religious groups that succeed in satisfying the natural desire for religious understanding gain a larger share of the religious market (Seabright, 2024).

The mistake of the Christian Integralists (both Catholic and Protestant) in rejecting Lockean religious liberty and toleration and affirming Christian Theocracy (or Christian Nationalism) is their failure to see how any theocratic attempt to suppress religious pluralism must be oppressively unjust and also contrary to the religious voluntarism practiced by the early Christian Churches.

We can see then how a Darwinian Lockean Liberalism can explain natural religion and can secure the religious liberty and toleration that respect religious pluralism and allow every individual to satisfy his natural desire for religious understanding in his own way, while allowing all others the same religious liberty.

Merry Christmas and Happy Holidays!

REFERENCES

Barrett, J. 2004. Why Would Anyone Believe in God? Lanham, MD: Rowman and Littlefield.

Bering, J. 2011. The Belief Instinct: The Psychology of Souls, Destiny, and the Meaning of Life. New York: W. W. Norton.

Collins, F. S. 2006. The Language of God. New York: Free Press.

Darwin, C. 1879. Letter to John Fordyce, May 7. Cambridge, UK: Darwin Correspondence Project, Letter No.: DCP-LETT-12041.

Darwin, C. 1936. The Origin of Species & The Descent of Man. New York: Random House, The Modern Library.

Darwin, C. 1969. The Autobiography of Charles Darwin. Ed. N. Barlow. New York: W. W. Norton.

Dilley, S., ed. 2013. Darwinian Evolution and Classical Liberalism: Theories in Tension. Lanham, MD: Lexington Books.

Ham, K. 2017. "Young-Earth Creationism." In J. B. Stump, ed., Four Views on Creation, Evolution, and Intelligent Design. Grand Rapids, MI: Zondervan.

Holloway, C. 2006. The Right Darwin? Evolution, Religion, and the Future of Democracy. Dallas: Spence Publishing.

Laslett, P. 1970. Introduction. In: John Locke, Two Treatises of Government: A Critical Edition with an Introduction and Apparatus Criticus, by Peter Laslett. Second edition. Cambridge: Cambridge University Press, pp. 3-152.

Locke, J. 1870. Four Letters on Toleration. London: Ward, Lock, and Tyler.

Locke, J. 2010. A Letter Concerning Toleration and Other Writings, M. Goldie, ed. Indianapolis: Liberty Fund.

Maurer, A. 2004. "Darwin, Thomists, and Secondary Causality." The Review of Metaphysics 57: 491-514.

Seabright, P. 2024. The Divine Economy: How Religions Compete for Wealth, Power, and People. Princeton: Princeton University Press.

Stump, J. B., ed. 2017. Four Views on Creation, Evolution, and Intelligent Design. Grand Rapids, MI: Zondervan.

West, J. G. 2006. Darwin's Conservatives: The Misguided Quest. Seattle, WA: Discovery Institute Press.

Wood, T. C. 2008. "Species Variability and Creationism." Origins Number 62: 6-24.

Wood, T. C., and M. J. Murray. 2003. Understanding the Pattern of Life: Origins and the Organization of the Species. Nashville, TN: Broadman & Holman.

Zuckert, M. 2002. Launching Liberalism: On Lockean Political Philosophy. Lawrence: University Press of Kansas.

Zuckert, M. 2005. "Locke-Religion-Equality." The Review of Politics 67: 419-431.

"I Do Not Believe in the Bible": Darwin's Correspondence on Biblical Religion

In September of 2015, this one-sentence letter by Charles Darwin was sold in an auction in New York City for $197,000.  This brief letter could command such a high price because scholars were unaware of its existence for over a hundred years, and it seemed to finally answer one of the most urgent questions that people have had about Darwin--Was he a Christian?  It did not answer, however, a different, although related, question--Does his theory of evolution require atheism?

Written on November 24, 1880, this letter was in response to a letter that Darwin had received the day before from Frederick McDermott, who was a stranger to Darwin.  Darwin was near the end of his life.  He would die a year and a half later at age 73.  (Darwin's correspondence is conveniently available online at the Darwin Correspondence Project at the University of Cambridge.)

McDermott said he desired to read Darwin's books, particularly after he had learned that Charles Kingsley had recommended them.  Kingsley had been a prominent clergyman, university professor, novelist, and chaplain to Queen Victoria; he was also a friend of Darwin's, who was one of the first people to endorse the argument of Darwin's Origin of Species.

McDermott wanted reassurance, however, that he could read Darwin's books without losing his faith in the New Testament.  "I fear my brain is not fine enough to argue out doubts which might be suggested by your works," he wrote to Darwin.  "My reason in writing to you therefore is to ask you to give me a Yes or No to the question Do you believe in the New Testament."  He promised that if he received an answer, he would not send it to "the theological papers" for publication.

Here's Darwin's letter in reply:

Nov. 24th 1880

Private

Dear Sir

I am sorry to have to inform you that I do not believe in the Bible as a Divine revelation, & therefore not in Jesus Christ as the son of God.

 Yours faithfully  Ch. Darwin

Darwin was reluctant to speak publicly about his religious beliefs, but he often spoke openly about this in letters that were marked "private."  Among his published writings, the most candid statement about his religious beliefs is the section on "Religious Belief" in his Autobiography, which he wrote in the summer of 1876, for publication after his death.   After his death in 1882, the Autobiography was published in 1887.  But, as I indicated in the previous post, his wife Emma had some passages about religion cut out because they were too disturbing.

If you go to the Darwin Correspondence Project, and search for the letters that mention religion or the Bible, you will find hundreds of letters, many of them addressed to Darwin from strangers like McDermott who want Darwin to tell them about his religious beliefs.  Some of these strangers were concerned about the eternal salvation of Darwin's soul.  A Joseph Plimsoll wrote six letters to Darwin--five in 1867-1868 and one in 1881--that were sermons filled with biblical quotations and pleading with Darwin to accept Jesus Christ as his personal savior. Plimsoll identified Darwin's "development theory" as atheism, and warned him that he would go to Hell for this if he did not ask for redemption.

But one should notice that neither in the letter to McDermott nor in any published writing or private correspondence does Darwin ever identify himself as an atheist or identify his scientific theory as atheistic.  On the contrary, he always insisted that his theory of evolution was compatible with theistic religion, although it was incompatible with a literal interpretation of the Bible as a divinely revealed history of the world.

Darwin's best brief statement of his religious views that is consistent with everything else he wrote about this is a letter to John Fordyce in May 7, 1879:

"It seems to me absurd to doubt that a man may be an ardent Theist & an evolutionist.--You are right about Kingsley. Asa Gray, the eminent botanist, is another case in point-- What my own views may be is a question of no consequence to any one except myself.--But as you ask, I may state that my judgment often fluctuates. Moreover whether a man deserves to be called a theist depends on the definition of the term: which is much too large a subject for a note.  In my most extreme fluctuations I have never been an atheist in the sense of denying the existence of a God.--I think that generally (& more and more so as I grow older) but not always, that an agnostic would be the most correct description of my state of mind."

There are five points here that Darwin repeated in his Autobiography and in his correspondence. 

(1) It is possible to affirm both theism and evolution--to be a theistic evolutionist--and people like Charles Kingsley and Asa Gray show this. 

(2) Darwin thinks his views of this issue should be of no special concern for others, because each person must make up his own mind based on his personal weighing of the pertinent arguments and evidence.

(3) Darwin finds this issue so mentally challenging that he fluctuates in his thinking, and he cannot come to any final conclusion.

(4) In all of that fluctuation, Darwin has never seen any good reasons to be an atheist, in the sense of denying the existence of God.

(5) And yet, Darwin has seen good reasons, especially in his later years of life, to be an agnostic, in the sense of being in such a state of ignorance that human reason is incapable of providing sufficient rational grounds to justify either the belief that God exists or the belief that God does not exist.

Prior to its official publication date of November 24, 1859, Darwin sent advance copies of The Origin of Species to a few people, including Charles Kingsley.  Kingsley wrote a letter to Darwin on November 18, 1859, which included this remark:

"I have gradually learnt to see that it is just as noble a conception of Deity, to believe that he created primal forms capable of self development into all forms needful pro tempore & pro loco, as to believe that He required a fresh act of intervention to supply the lacunas which he himself had made."

A few days later (December 2), Darwin wrote to John Murray, his publisher, that Kingsley's "capital sentence" should be inserted in the second edition of Origin, "in answer to anyone who may, as many will, say that my Book is irreligious."  This sentence was introduced into the concluding section of Origin as showing that there is "no good reason why the views given in this volume should shock the religious feelings of any one."

Kingsley's "capital sentence" is the first clear statement of the basic idea that is today called theistic evolution or evolutionary creation.  For example, theistic evolutionist Dennis Venema echoes Kingsley's sentence in his new book--Adam and the Genome (coauthored with Scot McKnight)--when he writes: "Evolution . . . may be God's chosen design to bring about biodiversity on earth. . . . Indeed, making an object that can self-assemble would require a design far superior to that of an object that requires manual assembly. . . . I view evolution as God's grand design for creating life" (89).

The best proponent of theistic evolution among Darwin's correspondents was Asa Gray, a professor of botany at Harvard University, who was the greatest American botanist of the 19th century, who was a devout orthodox Christian, and who exchanged hundreds of letters with Darwin from 1843 until Darwin's death in 1882.  The number of these letters peaked in the period of 1860 to 1864, when Gray was the leading American scientist defending both Darwin's science and the compatibility of his science with theistic religion.

In a letter to Gray on May 22, 1860, Darwin said: "Certainly I agree with you that my views are not at all necessarily atheistical."  Darwin and Gray agreed that God did not have to miraculously intervene throughout history to specially create every species and form of life.  But they also agreed that God could have originally created the laws of nature so that natural evolution could spontaneously unfold within those laws.  Darwin thought that the human mind generally, including his own mind, was "instinctively" by an "inward conviction" inclined to see divinely intelligent design at the origin of matter, life, and the human mind; but it was hard for him to see how some divine design at the beginning of everything could be manifest in the seemingly random contingencies of the natural world.   

In his many letters to Asa Gray where he takes up the theological arguments, Darwin repeatedly expresses the frustration of reaching the limits of human reason in trying to resolve fundamental mysteries: "I feel most deeply that the whole subject is too profound for the human intellect.  A dog might as well speculate on the mind of Newton.-- Let each man hope & believe what he can.--" (May 22, 1860).

There are some fundamental mysteries in the universe, Darwin suggests, and science might never be able to fully resolve these mysteries because of the limitations of human experience and human reasoning.  But it does not follow from this fact of human ignorance that there is no natural explanation for such mysteries, and that we must invoke God acting outside of nature.  To invoke God as the explanation is what Rebecca Goldstein calls the Fallacy of Using One Mystery to Explain Another.  Why is there something rather than nothing?  There is no good scientific or philosophic answer to that question, which points to the problem of ultimate explanation: we can keep passing the buck, but the buck must stop somewhere.  To say that God is the First Cause--the Uncaused Cause of everything--doesn't resolve the mystery because then we have the even greater mystery of how to explain God.  If we can say that God is uncaused or self-caused, then why not say that Nature is uncaused or self-caused?  (I have elaborated these points here and here.)

Darwin wondered whether the instinctive tendency of the human mind to see intelligent design in the universe could be trusted, or whether it reflected an unreasonable propensity of evolved human nature to anthropomorphic analogy.  He wrote about this in The Descent of Man, in explaining the evolution of religious belief.  The "belief in unseen or spiritual agencies" seems to be universal.  The simplest hypothesis to explain this, Darwin suggested, is that as human beings are aware of how their minds prompt them to act, and as they imagine that other human beings have the same mental agency in their actions, they are inclined to explain natural forces in plants, animals, and physical things as showing mental agency analogous to human minds; and this can lead to belief in supernatural minds that exercise intelligent agency in the world (Penguin Books, 2004, 116-118).

Recently, evolutionary psychologists have elaborated a Darwinian theory of religious belief as arising from a "hyperactive agency detection device"--that just as we believe in the existence of other human minds that we cannot directly observe, so we believe in the divine mind from projecting our mental experience onto the world.  As I have observed in other posts (here and here),  some of these Darwinian psychologists (such as Justin Barrett) see this as showing that Darwinian science is compatible with the truth of believing in God, others (such as Jesse Bering) see this as exposing belief in God as a fictional construction of the evolved human mind. For those like Barrett, religious belief is an adaptive truth. For those like Bering, religious belief is an adaptive illusion.  So, as Darwin indicates, it's not clear as to whether we are warranted in trusting our evolved propensity to religious belief.

Thus, as Asa Gray observed, "Darwinism may bear an atheistic as well as a theistic interpretation" (in his review of Charles Hodge's What Is Darwinism?).  So, if you're an atheist like Richard Dawkins, you can see Darwin's theory of evolution as making it possible for you to be "an intellectually fulfilled atheist" (The Blind Watchmaker).  But if you're a theist like Gray or Francis Collins, you can see Darwin's theory of evolution as showing the beautiful natural order that arises through laws of nature originally designed by God.

If you are a theistic evolutionist, however, your theism cannot be based on a literal interpretation of the Bible as a history of the world that was created in six 24-hour days, including the miraculous creation of Adam and Eve as the two individuals from whom all human beings descended.  While Darwin is open to the thought that the general laws of nature were originally created by God, he cannot take seriously the stories in the Bible about God's miracles as being literally true.

For example, Darwin received letters from people who were looking for ways to make his theory of human evolution from animal ancestors compatible with the story in Genesis about God creating Adam and Eve in His image, and thus set apart from the other animals.  But Darwin saw no need for this, because he did not see the Genesis account of creation as a divine revelation of a literally true history.

Leonard Jenyns was one of the people to whom Darwin had sent early copies of The Origin of Species.  Jenyns was an Anglican vicar and a naturalist, and he was one of the few naturalists to whom Darwin sent a letter in 1844 revealing Darwin's views on the transmutation of species.  Jenyns wrote to Darwin on January 4, 1860.  He indicated that he partly agreed with Darwin's theory of how species evolved from ancestral species.  But he was not convinced by Darwin's claim that "all organic beings that have ever lived on the earth, had descended from some one primordial form."

He was also worried that Darwin's theory as applied to human evolution would contradict the Genesis creation story:

"One great difficulty to my mind in the way of your theory is the fact of the existence of Man. I was beginning to think you had entirely passed over this question, till almost in the last page I find you saying that 'light will be thrown on the origin of man & his history.' By this I suppose is meant that he is to be considered a modified & no doubt greatly improved orang! I doubt if t his will find acceptance with the generality of readers--I am not one of those in the habit of mixing up questions of science & scripture, but I can hardly see what sense or meaning is to be attached to Gen: 2.7. & yet more to vv. 21, 22, of the same chapter, giving an account of the creation of woman,--if the human species at least has not been created independently of other animals, but merely come into the world by ordinary descent from previously existing races--whatever these races may be supposed to have been.  Neither can I easily bring myself to the idea that man's reasoning faculties & above all his moral sense, could ever have been obtained from irrational progenitors, by mere natural selection--acting however gradually & for whatever length of time that may be required.  This seems to be doing away altogether with the Divine Image which forms the insurmountable distinction between man & brutes."

In Darwin's letter of reply (on January 7), he passes over the question of the Divine Image quickly: "With respect to man, I am very far from wishing to obtrude my belief; but I thought it dishonest to quite conceal my opinion.-- Of course it is open to everyone to believe that man appeared by separate miracle, though I do not myself see the necessity or probability.--" 

In 1871, in The Descent of Man, Darwin did provide an evolutionary account of human reason and the moral sense as uniquely human, and yet derived from mental capacities shared with other animals, and without any reference to the Creation of Adam and Eve in God's Image.  If one agrees that "man is descended from some less highly organized form," and that "man is the co-descendant with other mammals of a common progenitor," Darwin concluded, then one "cannot any longer believe that man is the work of a separate act of creation" (Descent, Penguin edition, 2004, 676).

Twenty years after his exchange of letters with Jenyns, Darwin received a letter from William Tearle (in April 1880), who was worried that Darwin's theory was "antagonistic to the strict reading of the Bible."  He suggested to Darwin a new way to interpret the Bible's "Let us make man in our image": "May man not have been previously created, as an animal of a superior order, and God seeing that all living creatures required a head, and earthly master, he marked man as the most suitable, and then fashioned him after his own image."  (A similar interpretation of the Genesis creation story was advanced by C. S. Lewis in his book The Problem of Pain.)

Darwin's letter of reply (April 16, 1880) was brief and dismissive:

"I am sorry to say that I can be of no assistance to you.--Any remarks which I might make on your letter would as far as they had any influence, add to your doubts on subjects which you consider sacred."

 "In my opinion every man ought to weigh for himself impartially & anxiously al the arguments for & against any revelation ever having been made to man.--"

In an earlier letter (to Bartholomew James Sullivan, May 24, 1861), Darwin was dismissive about an article attempting to reconcile Genesis and science: "I am weary of all these various attempts to reconcile, what I believe to be irreconcilable."

But even if a literal reading of Genesis as natural history is irreconcilable with Darwinian natural history, the contradiction might be overcome by reading Genesis as telling stories with theological meaning that were never intended to be read as literal natural history.  Recently, some evangelical Christians who are theistic evolutionists have taken this position, which denies the historical reality of Adam and Eve. 

But many evangelical Christians now worry that this would deny the core doctrines of orthodox Christianity, while also denying the importance of the idea of humans created in God's image in supporting the moral dignity of human beings as endowed by their Creator with inalienable rights.  I will say more about this in future posts.

Debating Darwinian Liberalism (3): Dual Causality and Theistic Evolution

The second premise of Dilley's Syllogism is: "Darwinism denies Christianity."

I disagree.  Darwinian evolutionary science does not resolve the reason-revelation debate in favor of reason over revelation, because that science rightly understood (as I understand it!) recognizes that neither side in this debate can refute the other.  Darwinian evolutionary science also recognizes that there is a natural desire for religious understanding, and so atheism is contrary to our evolved human nature.

In taking this position, I am on the side of Charles Darwin as against Richard Dawkins.  Darwin never claimed, either in public or in private, that his evolutionary science proved atheism.  By contrast, Dawkins has proclaimed that the publication of The Origin of Species in 1859 made it possible for the first time in history to be an intellectually fulfilled atheist, because evolutionary science provided a rational refutation of revelation.  Remarkably, my nine critics who embrace Dilley's Syllogism agree with Dawkins that Darwinism is atheism, even though they think this Darwinian atheism can be refuted by revelation and intelligent design theory.

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 by rational proof to deny the possibility that nature itself is the contingent product of nature's God.

Darwin recognizes this in adopting the principle of dual causality, which originated in medieval Islamic and Christian theology.  He speaks of the laws of nature as manifested in evolution as "secondary causes," which leaves open the possibility of God's creative power acting through "primary causes" to create the original order of nature itself.  I have elaborated this point in a previous post.

Darwin thus allows for theistic evolution, which has been adopted by a long line of Christian thinkers, including C. S. Lewis, Francis Collins, and Alvin Plantinga.  Darwin rejects the "theory of special creation," which sees God as having to intervene miraculously in nature to specially create each form of life.  But Darwin allows for God to be understood as the First Cause, the uncaused cause of matter and life.

Most of my critics in Dilley's book seem to recognize that Darwin adopted the principle of dual causality, with natural evolution working through "secondary causes" and the Creator working through "primary causes" (3, 25-26, 87, 275-77, 284, 290).  Bruce Gordon, however, seems to reject the principle of dual causality as a blasphemous denial of God's omnipotence (168), which could be interpreted as his endorsement of a radical divine voluntarism that would make natural science impossible by denying the lawful regularity of nature (87, 162).

Darwin's dual causality allows him to conclude The Origin of Species with this famous sentence:  "There is grandeur in this view of life, with its several powers, having been originally breathed by the Creator into a few forms or into one; and that, whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been, are being evolved."

Dilley suggests that Darwin was not really serious in thus writing about life as "originally breathed by the Creator" into the first organisms, because he believes that for Darwin this language was merely a dishonest rhetorical gesture to placate his Christian readers (25).  Dilley quotes from a letter that Darwin wrote to Joseph Hooker in 1863: "I have long regretted that I truckled to public opinion & used Pentateuchal term of creation, by which I really meant 'appeared' by some wholly unknown process.--It is mere rubbish thinking, at present, of origin of life; one might as well think of origin of matter."  But notice what Darwin is saying here.  He regrets that using the "Pentateuchal term of creation" might be read as endorsing a literal reading of the Creation story in Genesis, which is what Biblical creationists have done.  And yet he wants to recognize the ineluctable mystery of how matter and life originated "by some wholly unknown process." 

Like C. S. Lewis, Darwin probably saw the Creation story in Genesis as a "myth" or "Hebrew folk tale."  (I have written about Lewis's position here and here.)  But he also saw this story as pointing to a mystery--the problem of ultimate explanation--that might be beyond the limits of natural reason.

All explanation depends on some ultimate reality that is unexplained.  All explanation presupposes the observable order of the world as the final ground of explanation that cannot itself be explained.  To the question of why nature exists or why it has the order that it does, the only reasonable answer is that we must accept this as a brute fact of our experience.  That's just the way it is! 

Now, of course, some religious believers will argue that we can reason to the existence of God as the simplest way of explaining the existence and the order of the natural world that is presupposed in all scientific explanations.  But those like David Hume can insist that there is nothing in our ordinary experience of the world that would make it likely, or even comprehensible, that something would have the power to create everything in the world out of nothing.  Moreover, the religious believers might admit that they cannot explain why God is the way He is.  Thus, in looking for ultimate explanation, we must stop somewhere with something that is unexplained--either an uncaused or self-caused Nature or an uncaused or self-caused God.  I have elaborated this thought in a previous post.

In response to such mystery, Darwin suggested in The Descent of Man, religious belief might have evolved through the natural tendency of the human mind to project intelligent agency and design onto the world by analogy with our experience of human intelligence.  Intelligent design theory is founded on such reasoning by anthropomorphic analogy.  In recent years, evolutionary theorists like Pascal Boyer, Justin Barrett, and Jesse Bering have elaborated Darwin's thought into a general theory of religious belief as an evolutionary expression of the human mind's propensity for detecting intelligent agency.  This leaves open the question of whether religious belief is an adaptive truth (as Barrett believes) or an adaptive illusion (as Bering believes).  But in either case, religious belief belongs to our evolved human nature.  Thus, as I reported in an earlier post on the MPS conference in the Galapagos, Leda Cosmides and Father Robert Sirico agreed that atheism is unnatural, because it is contrary to our evolved human nature.  Some previous posts on this can be found here, here, here, and here.

Was Man Created in God's Image? Or in the Image of Primates, With 16 Billion Neurons in His Cerebral Cortex?

 

                                  The Hidden Neuroscience in Michelangelo's "Creation of Adam"

THE CREATION OF ADAM'S PREFRONTAL CORTEX

Michelangelo's "Creation of Adam" is his visual depiction of the teaching in Genesis 1:27--"So God created man in his own image, in the image of God created he him; male and female created he them" (KJV).  Remarkably, Adam's body is already fully formed, but God is going to transmit to him something essential to his humanity through God's extended finger.  Presumably, God is endowing Adam with a human soul.  But how exactly is that to happen?  

We should notice that Michelangelo chose not to depict another image of Adam's creation from Genesis: "And the Lord God formed man of the dust of the ground, and breathed into his nostrils the breath of life; and man became a living soul" (2:7).  Michelangelo decided not to show God breathing into Adam's nostrils the breath of life as the source of ensoulment.

So what is it about the image of God flying through the air and stretching out his arm towards Adam lying on the ground that conveys the emergence of a human soul in Adam?  Some neuroscientists have pointed out that one can see a hidden drawing of the human brain in the image of God.  And God's right arm is extended through the prefrontal cortex, which is the part of the cerebral cortex responsible for decision-making, planning, creativity, working memory, and language.  Previously, I have written about how the liberty or freedom to choose between alternatives is a function of the cerebral cortex, under prefrontal control, in its reciprocal interaction with the environment. 

Is This a Hidden Drawing of the Human Brain?

We know that Michelangelo studied human anatomy carefully, and that he dissected human bodies and brains.  We know this from his anatomical drawings.  (Leonardo da Vinci--a contemporary of Michelangelo's--was also a talented anatomist of the brain.)  But of the thousands of Michelangelo's drawings, he destroyed most of them, and only about 600 have survived.  Some of these show drawings of the human skull and brain, but none of them show the exact outline of the cerebral cortex that some neuroscientists have seen hidden in Michelangelo's pictures.  There is certainly no evidence that Michelangelo understood the cognitive functions of the cerebral cortex and the prefrontal cortex.  Seeing a hidden neuroscientific message in Michelangelo's picture seems fanciful.

Nevertheless, we could argue for a modern neuroscientific revision of Michelangelo's picture, in which the image of God could be replaced by the image of the human cerebral cortex.  This would not have to be seen as an atheistic revision of the picture.  Because if the theistic evolutionists (like Francis Collins, Deborah Haarsma, and the last three Catholic popes) are correct, then God works through the natural laws of evolution to execute His creative design.  Some of the theistic evolutionists (like Pope Francis) say that while God works mostly through natural evolution rather than miracles, the creation of the human soul did require an "ontological leap"--a supernatural miracle--that transcended natural evolution.  But as I have argued, there are good reasons to believe that the natural evolution of the primate brain can explain the emergence of the soul in the human brain, so that no miracle was required.  And yet we still have to wonder what properties of the evolved human brain explain the amazing intellectual and emotional capacities of the human mind.

COUNTING NEURONS

Over the past fifteen years, the research of Suzana Herculano-Houzel, a Brazilian neuroscientist now at Vanderbilt University, has shown how this natural evolution of the human brain can be understood as based on the remarkable number of neurons in the human cerebral cortex, as it has emerged from the evolution of the primate brain, and thus we can see that we were created in the image of other primates, just as Charles Darwin suggested in 1871 in The Descent of Man (Gabi et al. 2016; Herculano-Houzel 2016, 2021; Herculano-Houzel and Lent 2005).  I am persuaded by most of what Herculano-Houzel says, although I will identify two points of disagreement with her.

                                                Suzana Herculano-Houzel Counts Neurons

How many neurons are in the human brain?  For many years, the answer from many scientists was 100 billion.  But, surprisingly, when Herculano-Houzel began some years ago looking for the original scientific research that provided evidence for this number, she found nothing.  She discovered that neuroscientists had repeated this number over and over again without realizing that there was no scientific verification for it.  

Moreover, she discovered that scientists had no reliable method for counting brain cells.  The most common method for attempting to do this was stereology: virtual three-dimensional probes are placed throughout thin slices of brain tissue from some part of the brain, then the number of cells within the probes are counted, and finally this is extrapolated to the total number of cells in the entire tissue volume.  The problem is that this works only for tissues with a relatively homogeneous distribution of cells.  In fact, the highly variable density of neurons across different structures of the brain, and even within a single structure, makes stereology impractical for counting the cells in whole brains.

Herculano-Houzel developed a new technique for counting neurons that starts with creating brain soup.  She dissects the brain into its anatomically distinct parts--such as the cerebral cortex, the cerebellum, and the olfactory bulbs.  She then slices and dices each part into smaller portions.  Next, she puts each small part in a tube and uses a detergent that dissolves the cell membranes but leaves the cell nuclei intact.  By sliding a piston up and down in the tube, she homogenizes this brain tissue into a soup in which the nuclei are evenly distributed.  She stains all the cell nuclei blue so that she can count them under a fluorescent microscope.  She then adds an antibody labeled red that binds specifically to a protein expressed in all neuronal cell nuclei, which distinguishes them from other cell nuclei such as glial cells.  Going back to the microscope, she can then determine what percentage of all nuclei (stained blue) belong to neurons (now stained red).  Finally, she can estimate the number of neurons for each structure of the brain.  She has done this in studying the brains of many mammalian animals.

Now she can tell us that the total number of neurons in the whole human brain is not 100 billion but 86 billion.  Of that total, 16 billion are in the cerebral cortex, which includes 1.3 billion neurons in the prefrontal cortex.  The cerebral cortex is the outer covering of the surfaces of the cerebral hemispheres.  The prefrontal cortex covers the front part of the frontal lobe of the cerebral cortex located behind the forehead.

FOUR ADVANTAGES

Comparing the numbers of neurons for the human brain with the numbers for other primate brains and other mammalian brains allows Herculano-Houzel to explain the conundrum of how the human brain can be at once so similar to and yet so different from other animal brains.  She makes four arguments about how the human brain gives human beings four kinds of advantages in their mental abilities: the primate advantage, the human advantage, the advantage of cooking, and the advantage of cultural learning.

Her claim that differences in cognitive capabilities across species can be explained by differences in the absolute numbers of neurons depends on a fundamental assumption.  If neurons are the basic units of brain networks for processing information, and if the networks are structured in similar patterns, then the greater the number of neurons in a network, the greater the capacity of the network for processing information.

The primate advantage.   Not surprisingly, larger brains tend to contain more neurons than smaller brains.  But different groups of animals show different scaling rules in proportioning brain size to number of neurons.  For example, a rodent cortex will have fewer neurons than a primate cortex of similar mass.   Primates always concentrate larger numbers of neurons in the brain than rodents of a similar, or even larger, brain size.

So here a capybara brain of 76 grams has 1.6 billion neurons, while a capuchin monkey brain of 52 grams has 3.7 billion neurons.  Comparison of primates with other mammals shows the same primate advantage:  in primate brains, the neurons are packed more tightly in a similar volume.  As primate brains, human brains have the same primate advantage over other mammals.  Thus, while the number of neurons in the human brain is remarkable, it is not extraordinary, because it falls on the primate scaling line: it's what one would expect for a primate with a body the size of the human body.  As Herculano-Houzel says: "The human brain is just a scaled-up primate brain: remarkable but not special."

One common objection to this is that the bodies of gorillas and orangutans can be as large as human bodies, but the brains of gorillas and orangutans are only about one-third the size of the human brain.  Gorillas and orangutans can weigh about 165 pounds, but their brains have only about 30 billion neurons, in contrast to the 86 billion neurons in the human brain.  Doesn't this show that the human brain is three times larger than what one would expect for a primate with the same size body? 

Herculano-Houzel's answer is that if one excludes the great apes (gorillas and orangutans), the scaling of the human brain in proportion to body size follows the same scaling rule as all other primates.  So the outliers here are not human beings but the great apes: it's not that human brains are too large for their bodies, but that gorillas and orangutans have brains that are too small for their bodies.

She explains this as showing that as primate evolution reaches the outer limits of the primate energy budget--the extra effort to find food--there is a tradeoff between brains and brawn.  More energy for a big body means less energy for a big brain.  The evolutionary history of the great apes shows a tradeoff  favoring big bodies and small brains.  By contrast, the evolutionary history of the human species shows a tradeoff favoring a typically primate slim body but a big brain.

The human advantage.  Herculano-Houzel's counting of neurons has allowed her to see that we human beings have one great advantage over all other animals: "we are the species that owns the largest number of neurons in the cerebral cortex--the part of the brain responsible for finding patterns, reasoning logically, expecting the worst and preparing for it, developing technology and passing it on through culture" (2016, x).  Notice that she is not saying that we have the largest number of neurons in the whole brain.  The African elephant brain has 257 billion neurons, three times our count of 86 billion.  But an amazing 98 percent of the elephant's neurons are in the cerebellum.  Although the elephant's cerebral cortex weighs over 6 pounds, it has only 5.6 billion neurons, far fewer than the 16 billion neurons in the human cerebral cortex weighing 2.6 pounds.  The sperm whale has the largest animal brain--weighing about 18 pounds--but Herculano-Houzel predicts that the number of neurons in the sperm whale's cerebral cortex is probably far fewer than 16 billion.

What Herculano-Houzel says about this human advantage confirms what I have argued about how the human mind or soul can arise from a natural process of emergent evolution in which differences in degree become differences in kind after passing over a critical threshold in the size and complexity of the primate brain.  As a consequence of her research, I can now identify that critical threshold as the remarkably large number of neurons in the human cerebral cortex and particularly in the prefrontal cortex.  Unfortunately, she herself does not see how her research supports the idea of emergent evolution.  That's my first disagreement with her.

In her book chapter on Darwin's Descent of Man--particularly, Darwin's chapter on "Comparison of the Mental Powers of Man and the Lower Animals"--she supports Darwin's claim that human mental powers differ from the mental powers of other animals only in degree and not in kind, and that if this difference were a difference in kind, that would deny his theory of human evolution from lower animals (Herculano-Houzel 2021, 48-49, 51, 61).

Herculano-Houzel does not see that Darwin in The Descent of Man is forced to contradict himself by both affirming and denying that there are differences in kind between human beings and other animals in their mental capacities.  Despite Darwin's explicit statement that humans differ only in degree, not in kind, from other animals, he implicitly recognized differences in kind.  That is to say, Darwin recognized that human beings have some mental traits that other animals do not have at all.

Darwin noted that self-consciousness is uniquely human: "It may be freely admitted that no animal is self-conscious, if by this term it is implied, that he reflects on such points, as whence he comes or whither he will go, or what is life and death, and so forth" (Descent, Penguin edition, 105).  Morality is also uniquely human: "A moral being is one who is capable of comparing his past and future actions or motives, and of approving or disapproving of them.  We have no reason to suppose that any of the lower animals have this capacity. . . . man . . . alone can with certainty be ranked as a moral being" (135).  And language is uniquely human: "The habitual use of articulate language is . . . peculiar to man" (107).

Darwin could implicitly affirm such emergent differences in kind without affirming any radical differences in kind.  Emergent differences in kind can be explained by natural science as differences in kind that naturally evolve from differences in degree that pass over a critical threshold of complexity.  So, for example, we can see the uniquely human capacities for self-consciousness, morality, and language as emerging from the evolutionary increase in the neurons of the primate brain, so that at some critical point in the evolution of our ancestors, the size and complexity of the brain (perhaps particularly in the frontal cortex) reached a point where distinctively human cognitive capacities emerged at higher levels of brain evolution that are not found in other primates.  With such emergent differences in kind, there is an underlying unbroken continuity between human beings and their hominid ancestors, so there is no need to posit some supernatural intervention in nature that would create a radical difference in kind in which there is a gap with no underlying continuity.  

Like Darwin, Herculano-Houzel fails to see how evolutionary science can recognize emergent differences in kind that arise from natural evolution while denying radical differences in kind that would require supernatural miracles.

The advantage of cooking.  If human beings are created in the image of primates, and yet they are unique among the primates because of those 16 billion neurons in the human cerebral cortex, why are human beings the only primate species to evolve such an increase in those neurons?  Herculano-Houzel's answer is that the evolutionary expansion of the human brain was made possible by the human invention of cooking.  Here she adopts the cooking hypothesis of Richard Wrangham in his book Catching Fire: How Cooking Made Us Human (2009).

The energy cost of the human brain is huge.  The brain is only 2 percent of the total body mass, but it consumes on average about 25% of the daily total energy budget for the human body.  On average 3.3 billion molecules of glucose are consumed per human neuron per minute.  6 kilocalories are consumed per billion neurons per day.  And so the more neurons in a brain, the more energy that a brain costs.

The caloric intake from the typical raw food diet of primates is not enough to supply the energy needs of the human brain.  The human controlled use of fire and the invention of cooking about 1.5 million years ago expanded the daily supply of energy to support the evolutionary expansion of the human brain, which can be seen in the fossil record of the huge expansion of the brain from Homo erectus to Homo sapiens.

The slicing and dicing of food and cooking with heat start the process of digesting food before it enters the mouth.  Cooking with heat breaks down the collagen fibers of meat and softens the hard walls of plant cells.  Cooked foods yield 100 percent of their caloric content to the digestive system.  Without cooking, our ancient human ancestors could never have fed their hungry human brains.

In a previous post, I have suggested that this cooking hypothesis for human evolution confirms what Lucretius said about the importance of fire and cooking for the evolutionary emergence of a fully human species.

The advantage of cultural learning.  The controlled use of fire and cooking are technologies that are invented and passed down across the generations by cultural learning.  As Herculano-Houzel observes, this shows us that "plenty of neurons aren't enough," because while having lots of neurons endows a brain with the capacities for complex cognition, turning those capacities into abilities requires cultural learning across an individual lifetime and across many human generations.

As I have indicated in some previous posts, cultural learning is not uniquely human because some other animals have cultural traditions of behavior.  But human beings are unique in their capacity for symbolic culture.

The behavioral inheritance system is the transmission of information among animals through social learning. For example, among some animals (including human beings) mothers transmit food preferences to their offspring, because information about what mother is eating is transmitted either in the womb or through suckling, so that the offspring inherits a preference for that food. More complex forms of social learning come through animal culture. For example, some chimpanzees can discover how to open nuts with a stone, and then pass on this practice within their group so that it becomes a social tradition. Different communities of chimps in Africa have different cultures based on distinctive profiles of traditional practices transmitted by social learning. As opposed to genetic evolution, cultural evolution is not blind but targeted to functional change.

The symbolic inheritance system is uniquely human because it shows the qualitative leap that defines our humanity as based on our capacity for symbolic thought and communication. Other animals can communicate through signs. But only human beings can communicate through symbols. The evolution of human language was probably crucial for the evolution of symbolism. Symbolic systems allow us to think about abstractions that have little to do with concrete, immediate experiences. Symbolic systems allow human beings to construct a shared imagined reality. These symbolic constructions are often fictional and future-oriented. Art, religion, science, and philosophy are all manifestations of human symbolic evolution. 

Herculano-Houzel gives a good account of human cultural evolution as driven by six technological revolutions (2016, 206-213).  But she doesn't explain why the pace of that technological progress has become so rapid over the past 300 years.  I have argued that the best explanation for this accelerated human progress is the symbolic niche construction of Lockean liberalism, which has sustained the freedom for innovation that has made it possible for the Earth today to support a population of over 8 billion people who are living longer and healthier lives on average than has ever been possible.  That is a stunning enhancement of Darwinian survival and reproductive fitness through cultural evolution.

THE SYMBOLIC EVOLUTION OF RELIGIOUS BELIEF IN "METAPHYSICAL ORIGINS"

The evolved cognitive capacity of the human brain for symbolic cultural learning includes a propensity to religious belief, which can include the belief that human beings were created in the image of God, and that this endowed human existence with a supernatural purpose.  Herculano-Houzel fails to take that religious belief seriously as a part of human cultural evolution, and that's my second point of disagreement with her.  She does say that the human brain gives human beings "the ability to ponder our own material and metaphysical origins" (2016, 215).  But she says nothing more about how the religious belief in "metaphysical origins" might be rooted in the evolutionary psychology of the human brain.  In The Descent of Man, in his chapter on the "mental powers of man and the lower animals," Darwin comments on a long list of mental powers, concluding with "belief in God, spiritual agencies, superstitions."  In her commentary on this chapter, Herculano-Houzel is silent about this.

If she had examined that last part of Darwin's chapter on the evolution of the mental powers as leading to religious belief, she would have seen that Darwin anticipates the modern evolutionary psychology of religion as an expression of the human brain's evolved theory of mind or the "hyperactive agency detection device."  Darwin conveys this idea when he says that the earliest manifestation of religious belief is "when anything which manifests power or movement is thought to be endowed with some form of life, and with mental faculties analogous to our own" (117).  Through symbolic cultural evolution this "belief in spiritual agencies" or animism could eventually be expressed in the belief in the existence of an Omnipotent God who is the "Creator and Ruler of the universe" (116, 118).  This is the God depicted in Michelangelo's "Creation of Adam"--the God who created human beings in His image.

The evolutionary science of the brain can explain how this ability for believing in the existence of the Creator God evolved through the genetic evolution of the human cerebral cortex and prefrontal cortex and the symbolic cultural evolution of religious belief in monotheism.  But while some Darwinian psychologists (such as Justin Barrett) see this as showing that Darwinian science is compatible with the truth of believing in God, others (such as Jesse Bering) see this as exposing belief in God as a fictional construction of the evolved human mind. For those like Barrett, religious belief is an adaptive truth. For those like Bering, religious belief is an adaptive illusion.

Thus, we see that Darwinian science cannot resolve the Reason/Revelation debate.  But Darwinian liberalism can support the freedom of thought that promotes that debate.

Part of that Reason/Revelation debate is whether human beings have a natural need to see the purpose for their existence that can only come from believing in the revelation of a divine purpose for human life, or whether natural reason alone can give human life some purpose or meaning.  Some theistic scientists (like Deborah Haarsma) say that in answering our questions about the Universe, science can tell us when and how, but only religion can tell us who and why.

Friedrich Nietzsche thought that the cultural history of the "teachers of the purpose of existence" over thousands of years had changed human nature so that human beings had a culturally acquired need to see some cosmic purpose to their lives.  "Gradually, man has become a fantasizing [phantastischen] animal that has to fulfill one more condition of existence than any other animal: man has to believe, to know, from time to time why he exists; his race cannot flourish without a periodic trust in life--without faith in reason in life" (The Gay Science, sec. 1).  Consequently, Nietzsche observed, "I fear that the animals consider man as a being like themselves that has lost in a most dangerous way its sound animal common sense; they consider him the insane animal, the laughing animal, the weeping animal, the miserable animal" (sec. 224). 

Is this what happens when you have a brain with 16 billion neurons in its cerebral cortex fed by some delicious, cooked meals?

REFERENCES

Darwin, Charles. 2004. The Descent of Man. 2nd edition.  New York: Penguin Books

Gabi, Mariana, et al. 2016. "No Relative Expansion of the Number of Prefrontal Neurons in Primate and Human Evolution." Proceedings of the National Academy of Sciences 113 (no. 34): 9617-9622.

Herculano-Houzel, Suzana. 2016. The Human Advantage: A New Understanding of How Our Brain Became Remarkable.  Cambridge, MA: MIT Press.

Herculano-Houzel, Suzana. 2021. "Remarkable But Not Extraordinary: The Evolution of the Human Brain." In Jeremy M. Desilva, ed., A Most Interesting Problem: What Darwin's 'Descent of Man' Got Right and Wrong About Human Evolution, 46-62.  Princeton: Princeton University Press.

Herculano-Houzel, Suzana, and Richard Lent. 2005. "Isotropic Fractionator: A Simple, Rapid Method for the Quantification of Total Cell and Neuron Numbers in the Brain." Journal of Neuroscience 25: 2518-2521.

Wrangham, Richard. 2009. Catching Fire: How Cooking Made Us Human. New York: Basic Books.