Saul Kripke turned 65 in November, just a moment ago, existentially speaking, so earlier this week the philosophy program at the Graduate Center of the City University of New York convened a two-day conference celebrating his birthday and work. Mr. Kripke, who has a similarly enlightened view of time, turned up half an hour late for the opening ceremonies.

In many circles, Mr. Kripke, who in 2001 was awarded the Schock Prize, philosophy's equivalent of the Nobel, is thought to be the world's greatest living philosopher, perhaps the greatest since Wittgenstein. Mr. Kripke is actually superior to Wittgenstein in at least two respects. Wittgenstein did not accomplish some of his most important work while still in high school. And unlike Wittgenstein, who was small, slender and hawklike, Mr. Kripke looks the way a philosopher ought to look: pink-faced, white-bearded, rumpled, squinty. He carries his books and papers in a plastic shopping bag from Filene's Basement.

Mr. Kripke, a rabbi's son, grew up in Omaha, and by all accounts was a true prodigy, so brilliant and precocious that the so-called prodigies of today are by comparison mere shadows flickering on the wall of our collective cave. In the fourth grade he discovered algebra, which he later said he could have invented on his own, and by the end of grammar school he had mastered geometry and calculus and taken up philosophy. While still a teenager he wrote a series of papers that eventually transformed the study of modal logic. One of them, or so the legend goes, earned a letter from the math department at Harvard, which hoped he would apply for a job until he wrote back and declined, explaining, "My mother said that I should finish high school and go to college first."

The college he eventually chose was Harvard. "I wish I could have skipped college," Mr. Kripke said in an interview. "I got to know some interesting people, but I can't say I learned anything. I probably would have learned it all anyway, just reading on my own."