Imagine an utterly irrepressible smile stretching across a child's face. Almost anyone seeing such an expression believes the child is experiencing some sort of delight. But why do we believe this? Reasoning from premises about bodily demeanor to conclusions about mental states is fraught with difficulty—famously so. Even the most promising arguments are halting gestures at our effortless movement in thought. From a very early age, we just find ourselves possessed of a conviction about the state of mind behind beaming faces—a conviction that neither claims the aid of arguments nor fears their failure. This tendency to form beliefs about the mental states of others on the basis of facial expressions is, of course, resistible and responsive to cultural influences. But a tendency is there to be shaped or resisted, and to blaze the trail our painstaking arguments attempt to follow.

For some time now philosophers have been interested in exploring the idea that belief in God is based on similar tendencies. But why think so? How should we understand the proposal? What implications does the idea have for the traditional arguments of natural theology? Does the proposal support or undermine the claim that belief in God is based on evidence, perhaps even good evidence? Is the proposal supported or undermined by the emerging scientific accounts of the origin of religious belief? In Natural Signs and Knowledge of God: A New Look at Theistic Arguments, C. Stephen Evans offers excellent answers to these excellent questions.

Evans' book is a characteristic combination of careful attention to neglected historical ideas and insightful analysis of a broad range of contemporary issues. This slim volume rewards readers with a theory of natural signs, a state-of-the-art assessment of three traditional arguments for the existence of God, and a fresh approach to the issue of natural knowledge of God. Readers will also be left with some large, partly interdisciplinary questions. That's only fitting: the questions that emerge mark the fecundity, not the failure, of the approach.

Evans' reasoning unfolds from a simple question, often rushed past in discussions of natural theology. If the God of classical theism exists, what should we expect in the way of grounds for belief in God? Evans answers in a Pascalian vein: in light of God's love for creatures, we should expect belief in God to be grounded in a way that balances two competing considerations. Knowledge of God's reality is ultimately necessary for the development of loving divine-human relationships. So it would be contrary to God's loving purposes for belief in God's existence to be exceptionally difficult to achieve—so difficult, say, that belief in God is accessible only to those with advanced degrees in cosmology or philosophy. At the same time, loving relationships must ultimately be freely embraced. So it would be similarly contrary to God's purposes if the existence of God were coercively obvious—so obvious that those who are uninterested in, or resistant to, relationship with God are forced by reason alone to live in light of the reality of God. Evans thus expects the grounds for belief in God to be, in his words, widely accessible yet easily resistible.

Beliefs based on some sort of natural proclivity fill the Pascalian bill nicely. In the case of the smiling child, normal adults find belief in the child's inner state hard to suppress. Consequently, the belief is very widespread. Yet the belief is not fully determinate, nor are its grounds fully compelling. Rational people, subject to differing cultural influences, interpret the content of the belief in a variety of competing ways. Some manage to suspend belief in the mental life of others altogether. The fit between the Pascalian constraints and the appeal to natural tendencies is, very briefly, the motivation for Evans' approach, which he elaborates under the tutelage of a very different thinker, Thomas Reid.

The lesson Evans takes from Reid has been a long time coming. Reid himself never applied his most original ideas to belief in God, opting instead (as best we can tell) for a traditional evidentialist approach to natural theology. In our own day, those who have applied Reidian ideas to belief in God draw less from his theory of natural signs than from his (early externalist) account of knowledge. Oddly enough those who come closest to anticipating the Reidian ideas that interest Evans are not Reid's allies but his great competitors, Hume and Kant. We will return to the irony here shortly, as Evans uses it to great effect.

Reid famously argued that certain beliefs—like the case of the smiling child and, more important for his purposes, the existence of the external world—are grounded in the operation of natural signs. To get quickly to the heart of Reid's sign theory, think of natural signs as the mental parallel of bodily reflexes. Certain bodily stimuli are regularly connected with instantaneous and involuntary bodily motions—as in the case of sneezing, blinking, startling, and the like. These responses are not explicable in terms of other known principles of bodily change; they are not the result of conscious decisions, for example, or of the autonomic processes governing the motion of our internal organs. Thus we posit original principles of our nature—i.e., reflexes—to account for these patterns of change. Attributing these patterns to nature, however, is not incompatible with recognizing the influence of other factors. Thanks to the startle reflex, the rapid encroachment of a projectile triggers a burst of protective motion. But the precise manner and extent of the motion is partly the result of conditioning. Failure to respond appropriately to such stimuli can lead to very vigorous evasive maneuvers indeed! A pattern of successful responses, on the other hand, produces more athletically adept movements (e.g., catching the projectile). Some reflexes, like the reflex to withdraw from painful stimuli, may even be completely suppressed by such influences.

Reid sees the situation with respect to certain movements in thought as perfectly similar. Some thoughts have what Reid calls the power of suggestion, a technical term designating the ability of a thought about one thing (the sign) to bring immediately to mind a thought about another thing (the signified). The words you are reading are signs in this sense. Perceiving these words brings immediately to mind thoughts about Reid's theory. But these words are not natural signs. The connection between these words and the things they bring to mind is easily explained in terms of known principles of association. (Reid attributes the suggestive power of words to implicit human compact.) Where the power of suggestion is not explicable in terms of known principles for establishing connections between ideas, Reid sensibly attributes the power to original principles of our constitution.

Original principles of our constitution determine that one thought triggers another, but in at least some cases (Reid calls them acquired perceptions) the precise content of the second thought is variable and subject to the influence of other factors (e.g., prior reasoning and experience). Thanks to the operation of such open-textured principles, we see smoke and immediately think of fire; we hear a sound and immediately perceive the direction from which it comes; and a sommelier tastes a wine and immediately perceives its vintage. In some cases the response to natural signs is even completely suppressible. All bets are off, Reid thinks, about the direction of a sound heard in an echo chamber.

Arguments that retrace the connections established by natural signs inevitably fail, at least as strict proofs. It is precisely because the connection between the sign and thing signified is not fully explicable in terms of other known principles governing movements of thought that we invoke natural principles in the first place. But, equally predictably, the failure of such arguments does little to erode belief, and even the harshest critics of the arguments acknowledge the naturalness of belief. We are typically undeterred by the lack of decisive arguments for the external world or for the child's delight, for example, and the critics of such arguments themselves happily succumb to the power of the sign when they leave the philosophical parlor.

The idea that there are natural signs for the existence of God thus not only coheres with what we should expect if there is a God, it provides the basis of the new look at theistic arguments promised by Evans' subtitle. If theistic arguments attempt to capture movements of thought grounded in natural signs, we should expect them to fail as strict proofs—arguments that should convince any rational person. Yet we should also expect these arguments to express a very natural and compelling basis of belief. The central chapters of Evans' book argue that this is exactly what we find in the case of three traditional theistic arguments—cosmological, teleological, and moral. We find experiences of cosmic wonder, beneficial order, moral obligation, and human dignity motivating belief with a force that arguments fail to capture. It is with respect to this last point that Evans calls on the testimony of Hume and Kant to such great effect. Hume and Kant are among the most withering critics of natural theology in the history of philosophy. Yet each in turn recognizes a powerful natural tendency to believe in God on the basis of the beneficial order experienced in nature, and each concedes the naturalness of theistic belief on the basis of this tendency.

Evans' treatment of the theistic arguments may seem to be making the best of a bad situation in natural theology. Some will surely protest that the traditional theistic arguments are more successful than Evans' analysis suggests. Others will claim that the arguments are much worse off than he allows; not only do they fail strictly speaking, they have no appeal that survives critical scrutiny. If Evans is right, of course, the situation is not really bad to begin with, but is instead in the ballpark of what we should expect if there is a God. These issues deserve more attention than they can receive in this short review. But a final assessment of Evans' approach is likely to turn on other issues that cannot be adequately treated even within the confines of a large book.

At the end of the day, Evans offers a story about the grounds of belief in God, where "grounds" has strongly psychological connotations concerning the mechanism by which belief in God is produced. Such proposals—like Reid's account of the origin of belief in the child's delight—face two large questions, both of which Evans broaches by way of conclusion. The first question for his approach is philosophical. How does such an account of the grounds for belief in God bear on the epistemic merits of theistic belief, and specifically on the merits required for knowledge? Unsurprisingly, the answer depends entirely upon one's account of the nature of the various epistemic merits, and of the kind and degree of such merits required for knowledge. Evans can hardly be faulted for failing to settle the central questions of epistemology in this book. He wisely tries, instead, to show that the epistemic merits of beliefs based on natural signs can be articulated in a variety of epistemological frameworks. The most promising frameworks all have a place for knowledge that is well-grounded but not acquired by inference. In this way Evans shows that a case can be made for the reasonableness of belief in God on the basis of natural signs regardless of the way one resolves the big questions in epistemology.

The second crucial question for Evans' approach is empirical. Is his hypothesis about the triggers of belief in God borne out by research in psychology and cognitive science? The sheer prevalence of some form of theistic belief in human communities offers some evidence that belief in God is grounded in a natural mechanism of some kind or other. But Evans rightly notes that it would take more research, and indeed fairly sophisticated research, to determine whether the experiences he describes are among the natural mechanisms at work. The rarity of philosophy that relates so directly to empirical research makes that last sentence particularly noteworthy. Given the ascendancy of debunking naturalistic accounts of the origin of theistic belief in the human sciences, the empirical questions Evans' approach raises are not only noteworthy, they are urgent. Natural Signs and Knowledge of God has much to offer philosophers and theologians, but the most significant contribution of Evans' book may well be to motivate and otherwise support broadly theistic research programs in the human sciences.

Todd Buras is associate professor of philosophy at Baylor University.

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