"The best lecture I ever heard at Columbia." That stopped me in my tracks. I heard so many good ones, so many entertaining ones, even several that I remember in detail.

Names crowd in, names of faculty and guest speakers: Sidney Morgenbesser, Alfred Hitchcock, Jacques Barzun, Fred Fielding, Ernest Nagel, Gene Santomasso, Saul Kripke, David Kaplan, Noam Chomsky, Tom Kuhn, van Quine, Herb Terrace, Hilary Putnam, Arthur Danto, Mark Steiner, Paul Kristeller, Jim Higginbotham, Mary Mothersill, Robert Cumming.

But the best of them all? My first reaction was that I could not possibly pick out a best lecture. But it got me thinking, and my thoughts eventually led me to this: there was indeed a best lecture, from which I learned a life-long lesson, in the fall of 1972.

The speaker, Georg Henrik von Wright, did not make my list of favorite speakers. His lecture was neither exciting nor informative--not, at least, to me as a 22-year-old with other interests in philosophy. I found the topic utterly boring. I went because it was an important lecture series for which von Wright had prepared carefully, an honorary series of four lectures to be given over a period of two months, and because I thought philosophy was to be my career.

High time to see the big dogs in action. Professor von Wright was decidedly a big dog. He had succeeded Wittgenstein at Cambridge, and at the time was a senior researcher at the Academy of Finland and visiting professor at Cornell.

In my case, what made his talk so special was neither content nor method of delivery. I remembered it because of what happened at the very outset.

Von Wright started with a careful description of the premises he was going to build upon in the series of lectures. These would form the solid foundation upon which he would construct his detailed argument concerning determinism in natural and human events. Even at this early juncture in his lecture, I was having trouble keeping all the threads together in my mind.

To my rescue came Sidney Morgenbesser, who raised his hand from the back of the room, even though it was hardly the time for questions. He asked a question that I did not fully understand, but I got this much from it: Morgenbesser was challenging one of von Wright's most fundamental premises about human action.

Given that von Wright had prepared so carefully for this lecture, and given the importance that he had clearly placed on the reliability of these premises, I expected that he would have a ready answer to Morgenbesser's friendly challenge. Instead, as Morgenbesser developed his point, I saw von Wright's pale skin start to turn a bright red.

There was a long pause. After what seemed to me an eternity, von Wright allowed that he had not considered the point made by Morgenbesser, and that he would have to re-evaluate a major part of his argument, and rethink his lectures.

He almost had a conversation with himself right there on the stage, sorting out what he could and could not continue, and then launched into the rest of his talk. I was utterly dazzled by the intellectual honesty on display. Since then, I have never witnessed its ilk. Very few of us have learned how to question our cherished assumptions freely, much less to do it while on public display. It was Columbia--and philosophy--at its very best.