This is premium Pinker, and while he ranges across the social sciences his primary focus here is on language, where he is unparalleled. His goal is to examine the nature of language and tease out the aspects of human nature that language embodies and elucidates. Note that the very concept of `human nature' is anathema to many of the postmodernists. Have no fear, because Pinker doesn't. He relishes the opportunity to burst the bubbles of political correctness, particularly with the use of hard facts and common sense.
His task here is complex, since language is so complex, but his writing is always lucid and to the point. He takes verbs, for example, and examines the ways in which they can and cannot be used, the functions that they can and cannot serve and the forms of human reasoning which they undergird. This can be heady stuff but it reads beautifully as we watch a mind that is both rigorous and playful catch us in the act of being, quintessentially, ourselves.
He is at his best when he is pulling together the insights of linguists, evolutionary psychologists and neuroscientists--something he does with ease and clarity. After he proceeds step by step and chapter by chapter he sums it all up in a concluding chapter that is a model of transparent complexity.
Although the materials are different, this book is like Kant's Critique of Pure Reason, its goal being the identification of those aspects of ratiocination that are uniquely human. The difference here is that Pinker draws specifically (and extensively) on the materials of language, draws more conclusions than Kant and does so in accessible and often amusing prose.
Pinker is one of a handful of centrally-important public intellectuals in America. Don't miss his latest (and if you've missed such important, former books as The Blank Slate--you know now what to request for Christmas).