(Originally posted at http://joelnoche.multiply.com/journal/item/13/Proof on July 1, 2010 8:46 AM)

*Proof* is a beautiful play by David Auburn. It won the Pulitzer Prize in Drama and the Tony Award for Best Play in 2001, among other awards. (I got a copy of the play from BOOKSALE.)

The main character, Catherine, claims to have written a proof of a very important mathematical theorem. Hal, a mathematician, initially does not believe her, thinking that the proof was actually written by Catherine’s recently deceased father, a famous mathematician. Eventually, Hal comes to believe Catherine’s claim, and goes to her to apologize. The following conversation brilliantly shows how the concept of proof in mathematics differs from that in the “real world.”

HAL: Come on, Catherine. I’m trying to correct things.

CATHERINE: Youcan’t. Do you hear me?

You think you’ve figured something out? You run over here so pleased with yourself because you changed your mind. Now you’re certain. You’re so . . .sloppy. You don’t know anything. The book, the math, the dates, the writing, all that stuff you decided with your buddies, it’s just evidence. It doesn’t finish the job. It doesn’t prove anything.

HAL: Okay, what would?

CATHERINE:Nothing.