Not since the 18th century has there been so much argument about the mind. In that era, philosophers such as John Locke, Jean-Jacques Rousseau, David Hume, and Immanuel Kant argued about the relationships between thought and speech, and between sensation and knowledge, in terms that we still mull over today. Are human beings born with innate ideas, or are we just blank slates, filled up by experience as we grow up? Is language something that uniquely makes us human? Do words really represent things in the world or are they markers of ideas inside our brains? Is there a language of thought itself, or do different languages embrace and shape the world in different ways?

Such questions have been asked afresh in recent years, not only by philosophers and linguists, but also by cognitive scientists and evolutionary biologists seeking the origins of human sensibility. Among the most prolific and most public of the current generation of inquirers into human understanding is the Harvard psychologist Steven Pinker. In a veritable bookshelf of recently published volumes, he has argued for what might be called a soft innatism: a theory of mind that holds that certain concepts or ways of thinking are hardwired into our brains at birth.

Not everything, Mr. Pinker would claim, comes with the child out of the womb — he rejects, for example, the linguist Jerry Fodor’s notion that we are born with some 50 thousand concepts and that every human language has a way of representing, in a core vocabulary, this embedded stock of ideas. Mr. Pinker believes in something he calls “conceptual semantics.” As he puts it in his new book, “The Stuff of Thought” (Viking, 512 pages, $29.95), “Word meanings are represented in the mind as assemblies of basic concepts in a language of thought.” All human beings do not necessarily have all the same structures of language or expression. Rather, we have a “sensitivity to subtle semantic distinctions” — a way of recognizing differences between certain kinds of actions or conditions.

We all have, according to Mr. Pinker, ways of expressing place and movement, ways of distinguishing actions in time, and ways of expressing causal relationships. Not everybody in the world expresses these things in the same way. But just about everybody has some way of expressing them. Mr. Pinker’s view is therefore different from those who believe in a set of absolute innate ideas: the notion that, not only do we have a concept of, say, killing, but we all have, whatever our language, a word for “kill.” Instead of this kind of absolutism, he holds that we all have “a cast of basic concepts.” These are far more abstract than killing, eating, or fishing. Instead, they are ideas about relationships.

This cast of basic concepts thus includes notions of things happening (not anything happening in particular; rather, the idea of happening). We all contrast, Mr. Pinker holds, coming from going; human from nonhuman, animate from inanimate. We cause things to happen; we prevent things from happening. These are the most general kinds of states, actions, and conditions, and these are what Mr. Pinker avers “to be the major words in a language of thought.”

This argument, what we might call Pinkerism, sets up a fundamental relationship between language and mind. Its implications have been seen across a gamut of human experiences: from understanding social relationships to developing artificial intelligence. Indeed, some adherents might claim that Mr. Pinker’s work gives us not just a template for humanity, but a program for computer architecture. In short, this is a blueprint for the brain, whether it be organic or virtual.

Mr. Pinker has written so much on this subject, and his work has been the object of so much debate, that one may wonder why we need another 400-plus page book on the matter. “The Stuff of Thought” adds little to the intellectual edifice of Pinkerism. It does, however, furnish that edifice’s rooms with popular examples, political and social implications, and reflections on the ways in which we all use language every day. There are extended chapters on swearing and obscenity, discussions of metaphor and figurative expression in literature and popular culture, and ruminations on the social codes of conversation.

Some of this material is fascinating. I was particularly struck by the discussion of “indirectspeech”: why we often make requests or indicate desire in oblique ways. “Would you like to come up for coffee,” has become an indirect request for sex. “I was wondering if you could pass the guacamole,” has become a polite way of saying, “Pass the guacamole.” Politeness and desire compel us to speak and write in subtle ways, and Mr. Pinker’s sensitivity and knowledge make his account far more substantive than those of other writers on this matter.

Then again, there is a fair amount of sheer attention getting in the book, especially the long chapter on “The Seven Words You Can’t Say on Television.” Mr. Pinker comes off as a comedian manqué, channeling George Carlin to make witty observations on why we can and cannot say things publicly. There’s nothing more uncomfortable to a young student than a middle-aged college professor working at being cool, and there are times throughout this book when I just cringed at the Groucho Marxisms or the list of verbs for sexual activity. That this list in particular ends with the Yiddish “shtup” can only be explained by Mr. Pinker’s belief that there is something inherently funny in the sonic concatenations of the shtetl.

Mr. Pinker, of course, is more than just a borscht-belt John Locke. He is the cognitive philosopher of our generation, and his work on language and mind has implications for anybody interested in human expression and experience. Like the paleontologists Stephen Jay Gould and Simon Conway Morris, or the biologist Joan Roughgarden, Mr. Pinker has changed the way we understand where we have come from and where we are going. For readers who can wade through the excesses of “The Stuff of Thought,” there is much to keep them thinking .

Mr. Lerer, a professor of English at Stanford University, last wrote for these pages on Christine Kenneally’s book “The First Word.”