There are several standard skeptical answers to the perennial question of why religions exist. They are said to provide explanations for natural phenomena, dreams, the origin of the world and the presence in it of human beings, or the existence of evil and suffering; they provide comfort in the face of suffering and death; they help to hold society together and give a basis for morality; or they are simply an expression of human gullibility and willingness to believe anything. Clearly there are difficulties with some of these ideas: the Calvinist doctrine of predestination, for example, could hardly be considered comforting. But Boyer finds that all such explanations, though often superficially plausible, are fundamentally mistaken, and in this book he sets out to tell us why.
At the heart of his explanation is the notion that religious beliefs arise from the normal functioning of the human mind. To account for this he introduces the notion of "inference systems": that is, explanatory devices adapted to different sorts of events. These devices are called on to explain ordinary occurrences such as a tennis ball breaking a window, but Boyer's claim, which he develops at length with abundant citation of anthropological material, is that exactly the same principle underlies the generation of religious beliefs in invisible beings and hidden influences on events.
This counter-intuitive notion is the basis of his theory of religion. It is, he insists, our ordinary explanatory devices that give rise to religious ideas, which is why certain kinds of religious belief are common all over the world whereas other, conceivable, beliefs are rare or absent. Moreover—and this is very important—these mental processes are not accessible to introspection; they produce beliefs but we don't know how these arise, which is why such beliefs are so persuasive.
As this outline will indicate, Boyer adheres to what has been called the "Swiss army knife" theory of how the mind works. That is, there are supposed to be numerous specialized functions within the mind, each adapted to a particular set of circumstances, rather than a general-purpose problem-solving ability. This theory derives from evolutionary psychology, which Boyer favours. He also makes use of the notion of culture as memes, originally proposed by Richard Dawkins, which implies that ideas compete with one another for propagation in a Darwinian manner. Successful memes spread from mind to mind: "[to] explain religion is to explain a certain kind of mental epidemic…". Almost all of the first half of the book is taken up with a detailed exposition of these ideas.
Having established the basis of his approach, Boyer then goes on to apply his theory to various kinds of religious phenomena. These include gods and spirits, death rituals, other types of rituals, and doctrinal beliefs. Here he provides a wealth of anthropological material. I was particularly struck by his statement that in the male initiation rituals found in a number of societies much is made of the secret knowledge supposed to be divulged to the young candidates, yet in the end it may turn out that the secret is trivial or that there is no secret at all. The candidates may also find themselves in double binds: damned if they obey their instructions and damned if they don't. They nevertheless usually feel as if they have been changed in some indefinable way.
I found this curiously reminiscent of the kind of paradoxes one encounters in many Zen stories, although Boyer does not make this connection. Boyer sees the function of such initiation rites as being to cement group solidarity, in which respect they clearly have much in common with secular "initiation rites" of the kind commonly practised during military training.
The final chapter confronts the fundamental question of why religious belief exists and is in a sense a recapitulation of what has gone before. Repeating his claim that the formation of religious beliefs is normal, not exceptional, Boyer takes issue with the view favoured by William James and others: viz. that religions begin with the experiences of mystics and visionaries which are then adopted by other people. The pronouncements of such exceptional people would have no effect, he remarks, were it not that they find an echo in the minds of others.
Also in this final chapter, Boyer discusses what is perhaps the most intriguing question of all: why are certain people apparently immune to religion? If it is normal for the human mind to form religious beliefs, does this mean that people who fail to do so are abnormal? Unfortunately, Boyer does not have an answer. Theories about the origin of religion apply only in the aggregate; they tell us about group psychodynamics but not about individual mental processes. What we can say, however, is that if it is true that religious belief is natural, religion will always be with us and will not be displaced by rationalism or science. Scientific thinking goes contrary to the spontaneous tendency of the mind: "science is every bit as 'unnatural' to the human mind as religion is 'natural'".
The great merit of Boyer's book is that it makes those of us who are skeptical about religious beliefs question the perhaps facile explanations we generally offer for their widespread existence. Our seemingly commonsense assumptions come up against considerable difficulties once we look outside the rather narrow boundaries of religion encountered by most Westerners.
The book has, however, one serious shortcoming: it does not offer a definition, even an approximate one, of religion, or even discuss why it is not possible to offer such a definition. As a result we never know exactly what we are dealing with. I suspect that this vagueness about what constitutes religion may be deliberate on Boyer's part, since it is the generalized nature of religious ideas that he wants to emphasize; he is more interested in resemblances than in differences. More than once he makes the point that various Christian beliefs and practices, such as the Catholic Mass, are just as bizarre as some of those reported by anthropologists from "primitive" cultures, the only difference being their familiarity.
No doubt for this reason, he concentrates on beliefs and practices that will be unfamiliar to most Westerners and has relatively little to say about Judaeo-Christian religions; thus the index has numerous entries for "gods and spirits" but only a couple for the Christian God. However, I think that he takes matters too far in failing to offer any definition of religion at all; the result is inevitably a certain fuzziness of focus. But although he may not have given us the full explanation of religion that his title promises, he certainly provides some new, and perhaps persuasive, arguments for a naturalistic view of the origin of religion.