In Why We Believe, the anthropologist Agustín Fuentes has written a clear and concise account of belief in light of his extensive knowledge of human evolution. Fuentes, who has taught at Notre Dame and is now a professor at Princeton, has written several books and articles that strive to present a biologically informed but non-reductive account of human nature. While himself religiously unaffiliated, he has frequently worked with theologians and scholars of religion in various collaborative science-and-religion projects. For an evolutionary thinker, he has a remarkable openness to what can be learned from religious traditions, religious philosophers, and theologians.

His new book is intended to show that, while we are the product of evolutionary processes and belong to the biological world along with countless other organisms, our distinctive capacities for imagining, feeling, and thinking give us special responsibilities to shape our societies more justly than we have in the past. Fuentes wants to explain “why we believe” partly in order to correct what he calls the dueling “fundamentalisms” of, on the one side, religious people who refuse to allow their view of human nature to be shaped by the impressive and growing body of knowledge about human evolution and, on the other, secular intellectuals whose enthusiasm for scientific methods of investigation has led them to embrace “scientism”—that is, the assumption that science alone provides the kinds of explanations that count as real knowledge. Fuentes rejects the assertion of scientism that “beliefs” are mere subjective opinions that educated adults should not take seriously. He argues instead that, while the sciences do yield a vast array of insights into how things work, there are many other paths to knowledge that involve believing claims we cannot justify on scientific grounds. Most of what we think is true is not “immanently generated knowledge,” as Bernard Lonergan points out in Method in Theology, and our reliance on the division of labor means that “belief plays as large a role in science as in most other areas of human activity.”

Fuentes appropriately begins his book by laying out what he means by “belief” and “believing.” In popular discourse, the act of believing is often taken to mean affirming the truth of a claim without having any empirical evidence for it. Philosophers have produced an enormous body of literature debating whether there are necessary and jointly sufficient conditions for “propositional knowledge.” A great deal of that literature is critical of the (purportedly) traditional theory of knowledge as “justified true belief.” But rather than wading into these waters, Fuentes draws on Terry Eagleton’s conception of believing as a state of being “completely in love with a concept, an experience, a knowledge.” The capacity to believe is based in our distinctively human capacity “to imagine, to be creative, to hope and dream, and to infuse the world with meaning.”

Believing is a pervasive part of human experience and by no means the sole preserve of the religiously devout. Fuentes distinguishes between our core ability to believe and our believing that this or that particular proposition is true. Here he unknowingly resonates with the Catholic vision of faith as comprising both fides qua creditur (the faith with which we personally assent to a truth) and fides quae creditur (the content of what we believe). Living faith, in the Christian sense, is not simply believing that God exists, but believing in, trusting, and loving God. This is not Fuentes’s concern, but Catholics will have no trouble understanding his distinction between our capacity to believe and the particular ways in which we exercise that capacity in our lives.


Our ancestors transformed the world not only for transactional but also for transcendent motives. The formation of beliefs about how things could and ought to be proves central to our ability to improve our lot.

Why We Believe is divided into three parts: How did we as a species come to believe? How do we believe now? And what do we believe now? We came to believe because of the social, emotional, and cognitive resources that emerged in our primate ancestors. We evolved from intelligent mammals who were highly adept at cooperating and forming strong groups. Fuentes understands human behavior as embedded in particular “niches,” which he defines as the “dynamic multidimensional space in which an organism lives.” The distinctively human niche is not only material, biological, and ecological, but also “imagined, perceived, and constructed”—in short, “meaning matters” and therefore so do beliefs. Organisms shape their habitats and vice versa. Human beings have shaped their habitats according to what they believe.

Evolution has made believing possible. Fuentes explains that between 2.3 and 1 million years ago our prehuman ancestors underwent significant changes in nutrition, the structures of their bodies and brains, and practices of caring for their young, making tools, avoiding predators, and obtaining supplies of food. In the past half-million years, massive growth in communication and social coordination led to better ways of understanding the world, imagining better alternatives, and then acting to transform it. These developments eventually led contemporary humans to produce innovations in food acquisition and storage, the domestication of plants and animals, the establishment of large residential settlements, and the identification of specific places, times, and relationships as sacred. Readers of Commonweal will appreciate Fuentes’s recognition that our ancestors transformed the world not only for transactional but also for transcendent motives. The formation of beliefs about how things could and ought to be proves central to our ability to improve our lot.

Part two of Why We Believe provides an account of how the human imagination enables us to combine cognitive and social resources to shape our world. “Believing is thinking beyond the here and now and investing to the extent that thinking becomes one’s reality,” Fuentes writes. Though he does not cite William James, his vision resonates with James’s “will to believe.” Belief is made possible by culture, a rich fund of meaning from which we constantly draw and to which our daily actions contribute. We are “not unique in having culture,” Fuentes writes, but the human niche is “completely intertwined with language, socially mediated and reconstructed history, institutions, and beliefs.” He insists that we not only “have” culture but actually “are” our culture: “literally, it is us and we it.” The experiences, memories, and thoughts made possible by our collective cultural resources help form our very bodies through their “neuroendocrine systems.”

Culture is obviously a necessary condition of mind—the set of “skills and processes that enable us to think and act”—and the distinctive core of the human mind is the imagination. Fuentes adopts the philosopher Anna Abraham’s theory of imagination as operative in our powers of sensation and movement, emotions, memory, “novel combinatorial” (generative) capacities, and “altered states.” The physiological structures of the human brain allow us to create symbolic and emotionally compelling mental representations of states of affairs that do not yet exist but could in the future.

Our evolutionary history makes such productive beliefs possible, but their particular forms are shaped by the distinctive cultures within which we live. This does not mean that our shared commitments and deeply held beliefs are in fact nothing but “mere” cultural constructs. “Cultural constructs are real for those who hold them,” Fuentes writes. “That is the way the human mind works.” Such a position allows him to take religions—and religious people—much more seriously than do some of his peers in evolutionary theory. The problem with the dominant evolutionary explanations of religion, he notes, is that they “largely ignore what the religious experience is for believers.” Fuentes knows that third-person analysis is valuable but cannot fully capture religious experience that takes place in the first and second person—when, as Martin Buber puts it, an “I” encounters the absolute “Thou.”

Part three of Why We Believe spells out the implications of this analysis for what people believe. Fuentes does not assume that evolution provides any help explaining the content of what people believe (e.g., why Presbyterians believe in double predestination or Catholics in transubstantiation), but he does think knowledge of our evolutionary past can shed light on why we develop religions, economic arrangements, and patterns of affiliation.


We can take the key features of his discussion of religion, economics, and love in order. First, Fuentes distinguishes religiousness from “religion” in general and particular “religions.” He not only acknowledges that the vast majority of people describe themselves as religiously affiliated, but—with a laudable mixture of respect, intellectual humility, and genuine curiosity—wants to understand why they do so.

Fuentes describes “transcendence” as being “beyond the limits of any possible experience” but then refers to religiousness as an “experience of transcendence.” “Transcendence” and “religious experience” are both notoriously vague concepts. There is a huge range in the different ways we experience going beyond the flow of everyday life. Such experience includes attending an exquisite musical performance, witnessing an extraordinary act of generosity, viewing a luminous work of art, and being awestruck at the birth of a child. All these experiences can be described as “transcendent” in at least three senses: first, they allow us to experience goodness, beauty, or truth in moments that surpass what we normally encounter in everyday life; second, religiously sensitive people often read these experiences as disclosing what is “most real” in human life; and third, these experiences can be called transcendent because they elicit feelings of piety, reverence, and gratitude for their divine source.

Agustín Fuentes (Mark Thiessen/National Geographic Creative)

Fuentes takes seriously the experience of particular persons and communities but, unlike William James’s The Varieties of Religious Experience, Fuentes’s book doesn’t take into account the specific testimonies of such persons or communities. His underdeveloped and rather abstract references to “religious experience” are not particularly satisfying. It would have helped if he had incorporated what the philosopher John A. Smith calls the “religious dimensions of experience”—a more accommodating concept than Fuentes’s “religious experience.” Fuentes might also have considered what Karl Rahner called “the experience of self-transcendence” involved in any true act of knowing or loving.

Fuentes argues that early human beings evolved to become highly social, meaning-making animals, who at some point began to have beliefs about supernatural agents. These beliefs were later taken up and extensively developed by religious institutions that arrived with the development of complex, large-scale societies between four thousand and eight thousand years ago. Fuentes rejects the two dominant evolutionary theories of religion. One of these holds that religion evolved because it was biologically adaptive; the other views religion as an accidental by-product (a “spandrel” in the language of Stephen Jay Gould) of cognitive and social traits that were themselves biologically adaptive. Neither of these approaches provides a satisfying account of the centrality of religion in the lives of so many people. Religious experience and beliefs offer ways of addressing a human need. Once their basic material needs are met, human beings naturally strive to go beyond the mere here-and-now and to relate themselves to larger purposes and schemes of meaning. Belief in transcendent reality thus provides the foothold for the later development of institutional religions, with their rituals, codes, and practices.

Fuentes’s own social and ethical concerns are on display in his chapter on economics, which he defines as “an organized system of activity involving the production, consumption, exchange, and distribution of goods and services.” Here he strongly challenges the assumption, common in modern and modernizing societies, that free markets are the most “natural”—and therefore the most rational and efficient—way to organize an economy. The dominance of free-market ideology is rooted in a widespread cultural acceptance of the myth of Homo economicus, according to which human beings are best understood as rational economic actors always seeking to maximize their self-interest. Fuentes reminds us that theories of behavioral ecology that describe “market competition” as pervasive in nature miss the richness and complexity of actual animal behavior. He worries that an uncritical acceptance of free markets as “natural” leads us to treat massive global inequality as “inevitable.” Though some part of us may still believe that real human beings are more complex and less predictable than Homo economicus, this reductive model is now “deeply ingrained in [our] communal psyche.”

The rise and growth of permanent large-scale settlements, cities, and then nations brought with it a shift from egalitarian to hierarchical social orders. Adam Smith argued that modern markets would produce a more extensive distribution of wealth, but today a global market economy coexists with massive inequality. Fuentes is not an economist and he does not propose his own alternative economic theory. His goal is simply to undercut the widespread view that human beings are essentially selfish, that free markets are the most “natural” way to organize economic systems, and that radical inequality is just the way things have always been—and always will be. Fuentes urges his readers not to passively accept current inequalities: “We made them, and we can change them.”


The last chapter of Why We Believe focuses on matters of the heart. “Love” and related terms have many meanings even within the history of Western culture. Love has been identified with eros (desire), philia (friendship), agape (self-gift), or with some combination of these. The strongest part of this chapter is its discussion of compassion; the weakest, its treatment of sexual love.

Fuentes argues that the evolution of biological, psychological, and behavioral traits made possible the emergence of maternal-offspring attachment and therefore enhanced the likely survival of human newborns, who are exceptionally immature. He theorizes that the maternal-offspring bond eventually facilitated the pair bonds of mating couples, and then extended further to promote a broader array of social and physiological bonds within the larger group. Drawing on the work of the anthropologist Walter Goldschmidt, Fuentes argues that evolution has produced in us a strong “affective hunger” that leads us to form social bonds far beyond what we see in any other species. Our ancestors extended compassion not only to their own offspring but to other members of their groups. Archeological evidence indicates “the emergence of consistent caring behavior that kept at least some of the injured, sick, and aged alive and part of the community” and produced a capacity to care for others “unrivaled in any other species.” Our strong in-group social cooperation, however, can sometimes be accompanied by hostility toward those outside the group.

Sex and marriage are the most controversial topics addressed in this book. We tend to draw sharp lines between sexual attraction, parental care, friendship, and other deep attachments, and often experience these kinds of relationship as fundamentally different from each other. But Fuentes claims that, “aside from slightly different hormone levels and other physiological responses related to sexual activity, romantic love is not biologically different from any other kind…. The idea that romantic love is distinct from other deep attachments is a product of cultural beliefs and worldviews, not our biology.” Fuentes argues that a great deal of anthropological literature challenges the assumption that we are naturally ordered to form exclusive, lifelong procreative pair bonds. (Catholics might think here of Pope Paul VI’s teaching about the “unitive” and “procreative” ends of sex.) According to Fuentes, sexual pair bonds are characterized by mutual sexual attraction that is preferential but not necessarily exclusive, reproductive, monogamous, or even marital. When he refers to marriage as “a recent occurrence in human history,” he seems to mean the natural history of our species rather than recorded history.

Fuentes rejects normative traditions that confine sexual activity to marriage, though he would perhaps be willing to have marriage continue as one lifestyle option among others. This is the direction in which Western cultures have been trending for decades. These anthropological observations are valuable for underscoring the challenges faced by those of us who endorse monogamy and would like others to do so as well. 

We might respond to that challenge by first asking how Fuentes moves from the “is” of diverse human social and sexual practices to the “ought” of moral standards. For most of recorded human history, there was no awareness of—let alone commitment to—human rights. These, too, are the “product of cultural beliefs, not our biology.” Belief in human rights is also “a recent occurrence in human history.” But rather than discount human rights for being of relatively recent vintage, we regard our belief in them as evidence of moral progress. Why can’t we say the same about the development of monogamous marriage, especially since the historical record shows that polygamous relationships have usually allowed powerful men to dominate their wives (and concubines)? More fundamentally, the social and ethical norms governing sexual behavior cannot be derived from knowledge of either our evolutionary past or our contemporary sexual proclivities, many of which reflect the impact of market forces, consumerism, and social media. Fuentes’s chapter on economics is sharply critical of the radical individualism of free-market ideology, but his chapter on love seems to endorse a radical individualism in sexual matters.

The norms governing sexual behavior cannot be derived from knowledge of either our evolutionary past or our contemporary sexual proclivities, many of which reflect the impact of market forces, consumerism, and social media.

The fact that we aren’t hard-wired to be monogamists does not mean we shouldn’t strive to be monogamous, any more than the fact that we are not hard-wired to be truth-tellers implies that we shouldn’t strive to be honest. The Christian tradition appreciates the special goods afforded by monogamous marriage, including deep interpersonal intimacy, acceptance, and the trust born of lifelong fidelity. In religious terms, the Protestant description of marriage as a lifelong covenant of love and the Catholic and Orthodox account of marriage as a sacrament both pledge the couple to love each other so truly that their relationship offers a glimpse of Christ’s love for the Church (Ephesians 5:30–31). Many of us are glad that civil marriage is now available to gay couples, and we applaud religious bodies that bless these unions. These developments extend the logic and benefits of monogamy.

Fuentes is strangely silent about families (both nuclear and extended), which seems odd for a thinker so attuned to our sociality. His criticism of belief in monogamous marriage does not mention the extensive social-scientific literature that shows that children raised by single parents are more likely to be poor, to have lower cognitive skills, to drop out of school, to have health problems, and to give birth outside of marriage themselves (see Kimberly Howard and Richard J. Reeves’s 2014 paper “The Marriage Effect: Money or Parenting”). Fuentes cares about the poor and laments inequality, but he does not acknowledge that the decline of marriage seems to contribute to both inequality and poverty (along with other factors, of course). Between 1980 and now, the rate of births to single mothers has doubled, from 20 to 40 percent. We are engaged in a massive social experiment that does not seem to be benefiting children. Of course, Fuentes is not against biological parents living with, and taking responsibility for, their children, but he doesn’t want society to put any pressure on parents to legally bind themselves to one another for life. Yet the legal and social bond of marriage is a stronger, more reliable form of commitment than the informal agreements of couples who cohabitate, and it is therefore a preferable arrangement for child rearing. Not taking into account the well-being of children is, at the very least, a significant oversight in Fuentes’s analysis of our beliefs about love.


Still, the strengths of Why We Believe significantly outweigh its weaknesses. Fuentes ought to be appreciated by readers of Commonweal primarily for his open-minded, non-reductive and non-polemical approach to religious matters. He has the confidence to think about nuanced and complex matters of belief that are often grossly oversimplified by popular writers. The very title gives a clue to the book’s tone: an aggressive secularist would be more likely to talk about “why they believe,” not “why we believe.” Fuentes does not say, “You (simple people) believe religion provides the path to God but we (scientists) know it is really nothing but a social institution constructed to serve certain social ends.” His non-reductive attitude to religion contrasts sharply with what we are used to getting from Richard Dawkins and other New Atheists, who believe society can be divided between the “brights” (who inhabit the “community of reason”) and the “dulls”—those incapable of rationality or invincibly ignorant.

Fuentes’s openness is remarkable. “Unlike many of my evolutionary explanation-oriented colleagues,” he writes, “I’m fully comfortable leaving open the possibility that some form of transcendent revelation plays a role in a religion’s particular beliefs.” This intriguing statement is partly just an expression of disciplinary self-restraint: as a scientist, Fuentes can reject only those claims that run against well-established scientific knowledge, and so he will not dismiss religious truth claims that can be neither proved nor disproved. This kind of humility should be normal; because it is not, it requires real intellectual courage. It will be met with mockery by militant atheists, and with gratitude by religious readers. Fuentes’s refusal to rule out the possibility that a religious tradition might really be shaped by divine revelation raises a host of questions, but these must be answered by theologians and philosophers rather than by anthropologists and evolutionary theorists.

Why We Believe provides a superb and very readable summary of one influential approach to our evolutionary past. Written in a graceful style, it briskly covers a vast amount of scholarly terrain in less than three hundred pages. And, like the best books in any field, it will leave the reader wanting to learn more.

Why We Believe
Evolution and the Human Way of Being
Agustín Fuentes
$28 | 280 pp.

Stephen J. Pope is a professor of theological ethics at Boston College. He is the author of A Step Along the Way: Models of Christian Service (Orbis, 2015).

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Published in the July/August 2022 issue: View Contents
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