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The Mental Proof. In this formulation, an all-intelligent Being is offered as the only explanation for the power of reason and for humanity's other nonmaterial qualities of mind and imagination. A contemporary restatement is the 1947 classic Miracles by the late English literary critic C.S. Lewis, the century's most read apologist for God. Lewis dismissed the philosophy that mind results from nature: "If any thought is valid, an eternal, self-existent Reason must exist and must be the source of my own imperfect and intermittent rationality."
America's leading orthodox Protestant philosopher of God, Alvin Plantinga of Michigan's Calvin College, develops a related argument from one of the pressing issues in modern epistemology. Though it sounds strange to the man in the street, philosophers ponder how an individual can know that there is any creature besides himself who thinks, feels and reasons, or how he can know that anything ever existed in the past. How, for instance, can we know if another person is in pain? Plantinga answers that such knowledge is acquired through analogy, and in God and Other Minds (Cornell; $13.50) he makes an intricate case that this is the way believers know God. Since it is perfectly plausible to infer that other minds exist, he thinks it is reasonable to believe that God does as well.
The Experiential Proof. Because religious experiences are so widespread, this argument runs, there must be something (or rather, Someone) inspiring them. Skeptics, of course, reply that experiences are subjective, hence unreliable as evidence, and besides they can be explained apart from God. Harvard's Quine, for example, dismisses beliefs as the product of "tradition, wishful thinking or something in the genes." However, one of Britain's most distinguished zoologists, Alister Hardy, begs to wonder. A project he founded at Oxford has issued a rigorous scientific study of 3,000 religious experiences, and reports a striking—and intriguing—commonality among them.
The Teological Proof. Here the infinitely complex structure of the universe is used to argue the necessary existence of an intelligent Designer. In English Archdeacon William Paley's famous analogy of 1802, anyone who sees a watch is forced to assume the existence of a watchmaker who made it. The marvels of nature's design, from snowflakes to developing embryos, are comforting buttresses to faith for many people.
Since the Enlightenment, though, philosophers have not been impressed. The great skeptic was David Hume (1711-76), who scoffed at the design argument because nature is so savage and wasteful that it might have been the work of "some infant deity who afterwards abandoned it, ashamed of his lame performance." Turned inside out, the proof is really a question: Could this intricate universe have evolved by pure trial and error? The last major philosopher to promote the argument, Britain's F.R. Tennant, wrote in 1934: "Presumably the world is comparable with a single throw of the dice. And common sense is not foolish in suspecting the dice to have been loaded."