Even if man really were nothing but a piano-key, even if this were proved to him by natural science and mathematics, even then he would not become reasonable, but would purposely do something perverse out of simple ingratitude, simply to gain his point.

—Fyodor Dostoyevsky, Notes from the Underground

(Self-promotion: this is the epigraph to the novella I'm working on, which is not really about rationality but is about what we're pleased to call "human nature", and which you may read the beginning of here if so inclined.)