Good Guesses

This paper is about guessing: how people respond to a question when they aren’t certain of the answer. Guesses show surprising and systematic patterns that the most obvious theories don’t explain. We offer a theory that does explain them: we propose that people aim to optimize a tradeoff between accuracy and informativity in forming their guess. After spelling out our theory, we use it to argue that guessing plays a central role in our cognitive lives. In particular, our account of guessing yields new theories of (1) belief, (2) assertion, and (3) the conjunction fallacy—the psychological finding that people sometimes rate conjunctions as more probable than their conjuncts. More generally, we suggest that guessing helps explain how boundedly rational agents like us navigate a complex, uncertain world.