The End of Decision Theory

Brian Weatherson (University of Michigan, Ann Arbor)

Abstract: There are a lot of rival decision theories on the market these days. But it's not always clear what question those theories take themselves to be answering. And once we get clear on what the question is, it's not clear why we should be interested in answering it. My talk is about this question, and why it is, or isn't, interesting. I'll argue that the question concerns a rather specific kind of idealisation: what would a person do if they had the same information and preferences as we do, but did not have ourcomputational limitations. Answering this question does not, I’ll argue, provide us with a guide to action. We are too different to a person with no computational limitations for that to be right. Rather, answering this question is useful in predicting and understanding how people behave in specified contexts. Decision theory, on my picture, is an input to useful models in social science. Understanding decision theory this way has implications for what a good theory of decision might look like.