This thing called "analytic philosophy"?the kind of philosophy almost universally practiced by academics in Britain, the U.S., and the rest of the Anglophone world?what the heck makes it go? Is its evolution a matter of incremental progress toward the truth? Or is it pushed this way and that by the shifting winds of fashion and personality? Why has metaphysics?the quest to discover the True and Ultimate Furniture of the Universe?made a roaring comeback over the past few decades, after being banished as nonsense by the logical positivists and ordinary-language philosophers of an earlier generation? And why does the name of Wittgenstein?once the revered deity of analytic philosophy?no longer strike fear in the hearts of today's practitioners?

Timothy Williamson, a professor of logic at the University of Oxford, offers some bracingly opinionated answers in his elegant conspectus of the field. What might surprise non-philosophers is the identity of who Williamson claims is "undoubtedly" the most influential figure in analytic philosophy today: not Wittgenstein, not Quine, not Kripke (the most recent philosopher, by the way, to make the cover of The New York Times Magazine), and certainly not Richard Rorty, but ... David Lewis (1941-2001), who was known as "the machine in the ghost" for his detached air and sheer computational horsepower. One of the oddest tidbits in this essay is that David Lewis's tutor at Oxford was none other than Iris Murdoch. Which causes one to wonder whether Lewis's "modal realism"?the doctrine that possible worlds are genuinely real, even those containing talking donkeys and such?was somehow implicit in The Sacred and Profane Love Machine.