Do humans act rationally? Economic theory has long told us the answer is "yes." But a half century ago, two psychologists — Daniel Kahneman and Amos Tversky — began to challenge this notion. Their work laid the foundation for behavioral economics and influenced many scholars who've followed in their footsteps. This week, we mark our 100th episode by talking with Daniel Kahneman about his collaboration with Tversky, and how their work transformed our thinking about judgment, memory, and the mind itself.