It's not every week that a thick scientific tome reaches the top of the bestseller lists; works by Stephen Hawking and Carl Sagan made it to the top spot. But when they do, it's important to give them a serious reading. The popular theories of today become tomorrow's unquestioned axioms. The No. 1 nonfiction bestseller How the Mind Works, by Steven Pinker, is every bit as modest as its title (which is to say, not very). But it's not pure science; it's an older discipline, natural philosophy. Mr. Pinker's ambition is to apply "computational theory" and an advanced mutation of hyper-Darwinism to every aspect of the human condition. He contends that the mind-not just the brain-is a very complicated computer, developed by nature for the purpose of thinking. And that's all it is. Beliefs and desires and intentions are just information, he says, bits and bytes of data being processed by our cranial Crays. That's all, so we can put aside our religious differences and sectarian strife, as well as our dogmatic morality. "We are organisms, not angels, and our minds are organs, not pipelines to the truth." Mr. Pinker constructs his new model on a foundation of unapologetic Darwinism, which he lays out thus: "In the beginning was a replicator." Like Darwin himself, he fails to specify where that replicator came from; what does that matter, he reasons, when "new computer simulations" have proven natural selection to be true? From these principles, the reader is led to the logical conclusions: "One of the reasons God was invented was to be the mind that formed and executed life's plans." "Free will is an idealization of human beings that makes the ethics game playable." And just to show that computational theory is entirely adequate, he goes on to explain why we like music, monogamy, adultery, tearjerkers, roller coasters, and our relatives. And so anything goes. It's no accident that Mr. Pinker is also the author of a recent article in The New York Times arguing for the moral acceptability of infanticide. "The right to life," he writes, "must come ... from morally significant traits that we humans happen to possess. One such trait is having a unique sequence of experiences that defines us as individuals and connects us to other people. Other traits include an ability to reflect upon ourselves as a continuous locus of consciousness, to form and savor plans for the future, to dread death and to express the choice not to die. And there's the rub: Our immature neonates don't possess these traits any more than mice do." In Mr. Pinker's construct, there's no difference between a mouse and a newborn baby, both of whom are subject to extermination. And that's the real point of the book. But it was not always so. Throughout history, many of the leading scientists operated from a Christian worldview. Three centuries ago, another scientist (and amateur computer geek) named Blaise Pascal addressed the same questions as Mr. Pinker. His answers, outlined in the unfinished book Pensées ("Thoughts"), are strikingly dissimilar. "Men despise religion," Pascal observes. "They hate it and are afraid it may be true." And this: "The more enlightened we are, the more greatness and vileness we discover in man." Boston College professor Peter Kreeft has ably annotated an edition of Pensées titled Christianity for Modern Pagans. There's no one better, he says, to address modernists such as Mr. Pinker than Pascal, the 17th-century French scientist. Pascal designed and built the first working computer (a present to his beloved merchant father, who had long columns of figures to add each day). He pioneered probability theory, and he performed experiments on air pressure and vacuums (including putting together the first vacuum cleaner). "He is three centuries ahead of his time," Mr. Kreeft writes in his introduction. "He addresses his apologetic to modern pagans, sophisticated skeptics, comfortable members of the new secular intelligentsia." Pascal agrees with Mr. Pinker that man is no angel: "Man is neither angel nor beast, and it is unfortunately the case that anyone trying to act the angel acts the beast." One last gem from Pascal: "Our religion is wise and foolish: wise, because it is the most learned and most strongly based on miracles, prophecies, etc.; foolish, because it is not all this which makes people belong to it.... What makes them believe is the Cross."