Pinker's position is a synthesis of standard cognitive science with equally standard neo-Darwinian, selfish-gene evolutionary theory, a combination called "evolutionary psychology" by its exponents. Since depressingly large segments of the educated classes either know nothing about these theories, or are hostile to them (quite often, both), Pinker provides two good early chapters ("Thinking Machines" and "Revenge of the Nerds," respectively) to make them plausible.
The mind, for Pinker as for almost all other cognitive scientists, is computational. This does not mean they think it works just like the computer you're reading this on, but that has representations, which it transforms in a rule-governed, algorithmic way. Moreover, the mind is not a single, general-purpose computer, but a collection of them, of "mental modules" or "mental organs," specialized as to subject matter, each with its own particular learning mechanism ("an instinct to acquire an art," in a phrase Pinker lifts from Darwin). This modularity is evident in studying how children learn (recall Pinker's background in language acquisition), and also from tracing the effects of brain lesions which, if sufficiently localized, impair specific abilities depending on where the brain is hurt, and leave others intact. Just as, baring developmental defects, wounds, or the ravages of disease, all human beings have the same physical organs, we all have the same mental organs, whose general structure is, again, the same from person to person.
The specification for these organs is genetic; like all "organs of extreme perfection and complication," they are evolutionary adaptations, shaped by natural selection to help our ancestors' genes propagate. An animal which lives off fruit in the tree-tops will do much better if it can see in depth and in color; thus we can, and Pinker devotes a long and excellent chapter to the computational mechanisms which let us do this, and how various illusions exploit their bugs. Other mental organs are postulated for other sorts of perception; for intuitive physics; for numbers; for "folk biology"; and of course for dealing with the most important organisms in the environment of a political animal, its fellow political animals. Pinker has little to say here about language, having already written the book on it; but there's plenty on the emotions, and on the consequences of the fact that "primates are sneaky baldfaced liars": for instance, we're wired in ways that let us easily solve tricky problems in logic if they are couched as catching someone cheating or breaking rules. Our minds, in short, are Swiss army knives, equipped with every gadget needed to get hunter-gatherers through the Paleolithic, now being put to unnatural uses.
I was going to follow this with a long list of the things Pinker is not saying (e.g., "Our genes control our actions"); but, the intellectual climate being what it is, Pinker has taken some care to point out that he is not saying them, and why those views are in fact wrong. Those who read the book with any care will not come away with these misconceptions, unless of course they are determined to find them there, and in that case this review will not reform them. That said, three points could stand some reinforcement.
First, the accusations of being an "adaptationist." This is Stephen Jay Gould's name for a scientist who regards every feature of an organism as an adaptation, and spins a Just So story to account for it. This creature, fortunately, belongs more to cryptozoology than zoology, as no adaptationist in this sense has ever been seen in the wild or exhibited in captivity --- not Richard Dawkins, not John Maynard Smith, not Bill Hamilton, not even E. O. Wilson himself. (Why someone as smart, learned and well-intentioned as Gould persists in his polemic against adaptationism, I am at a loss to understand.) Pinker certainly is not the Abominable Adaptationist, brought to ground at last in Building 20 at MIT.
Second, ethics. Ever since David Hume, the more clear-thinking philosophers have realized that one cannot go from is to ought, from facts about the world to injunctions about how to act and what is good. (There have been philosophers who've denied this; interestingly enough, they've tended to be the ones claiming that human nature is infinitely malleable.) Pinker, quite soundly, affirms this position, this separation between knowledge and ethics. Our having an inherited disposition towards doing Q says nothing one way or another about whether or not it is right to do Q. (We have, demonstrably, dispositions to make certain specific kinds of errors in logic and probabilistic reasoning, unless we carefully check ourselves; but they are errors.) The ethical implications of evolutionary psychology, certain irresponsible popularizers and muddled opponents to the contrary notwithstanding, are thus exactly nil; at best, like any science, it can tell us whether a certain course of action is likely to achieve the goals we have set ourselves.
Third, the matter of culture and upbringing, and the whole tired nature vs. nurture meshuggaas. On the last, Pinker is appropriately cutting, asking us to imagine the following bit of dialogue:
"This new computer is brimming with sophisticated technology. It has a 500 megahertz processor, a gigabyte of RAM, a terabyte of disk storage, a 3-D color virtual reality display, speech output, wireless access to the World Wide web, expertise in a dozen subjects, and built-in editions of the Bible, the Encyclopedia Britannica, Bartlett's Famous Quotations, [sic] and the complete works of Shakespeare. Tens of thousands of hacker-hours went into its design."Almost no one is quite so clueless as to take the part of the second speaker; but it comes very close to the received wisdom bestowed by an American college education, particularly in what passes for the liberal arts. In part Pinker's book is a running polemic against what evolutionary psychologists contemptuously call the Standard Social Science Model, that mish-mash of half-digested Freud, Skinner and Durkheim, where we are as puppets in the hands of our society (qui est donc cette dame?), or perhaps our potty-training. The study of culture cannot benefit from making demonstrably false assumptions about human psychology and the degree to which it can be changed by circumstance.
"Oh, so I guess you're saying that it doesn't matter what I type into the computer. With all that built-in structure, its environment can't be very important. It will always do the same thing, regardless of what I type in." [pp. 32--33]
Culture is important; upbringing is important; what Pinker is trying to explain are the mechanisms that let us have a culture and receive an upbringing, without which we would be like the fools in Jeremiah, "without understanding; which have eyes, and see not; which have ears, and hear not." The goal is not to explain the idiosyncrasies of particular cultures, still less the acts of particular people, but the capacities we all have, particularly those which make us universally capable of culture. This goal is important, attainable, and already partly attained; such is Pinker's message.
It's clear by this point that I approve of the message and the messenger. Pinker's writing --- clear, informal, witty, and usually good-natured --- is exemplary; the arguments are cogent; the evidence (from neuroscience, psychology, anthropology and paleontology) is well-marshaled and abundant. There are, of course, a few points where I reserve judgment --- in particular, I am leery of Frank Sulloway's ideas about birth-order and personality, but have not examined the relevant evidence in any detail --- but they're side-issues, and no one could make it through a fat book about everything that goes on between the ears without a few of them. How the Mind Works is, in a word, superb, and deserves the widest possible audience.