Deliberation Welcomes Prediction

Alan Hájek (Australian National University)

A number of prominent authors—Levi, Spohn, Gilboa, Seidenfeld, and Price among them—hold that rational agents cannot assign subjective probabilities to their options while deliberating about which one they will choose. This has been called the “deliberation crowds out prediction” thesis. The thesis, if true, has important ramifications for many aspects of Bayesian epistemology, decision theory, and game theory. The stakes are high.

The thesis is not true—or so I maintain. After some scene-setting, I will precisify and rebut several of the main arguments for the thesis. I will defend the rationality of assigning probabilities to options while deliberating about them: deliberation welcomes prediction. I will also consider applications of the thesis, and its denial, to Pascal’s Wager.