Published online by Cambridge University Press: 01 April 2022
Crucial to bayesian contributions to the philosophy of science has been a characteristic psychology, according to which investigators harbor degree of confidence assignments that (insofar as the agents are rational) obey the axioms of the probability calculus. The rub is that, if the evidence of introspection is to be trusted, this fruitful psychology is false: actual investigators harbor no such assignments. The orthodox bayesian response has been to argue that the evidence of introspection is not to be trusted here; it is to investigators' dispositions—not to their felt convictions—that the psychology is meant to be (and succeeds in being) faithful. I argue that this response, in both its orthodox and convex-set bayesian forms, should be rejected—as should the regulative ideals that make the response seem so attractive. I offer a different variant of bayesianism, designed to give the evidence of introspection its due and thus realize (as I claim the other forms of bayesianism cannot) the prescriptive mission of the bayesian project.
I would like to thank Daniel Hausman, Paul Horwich, Richard Jeffrey, Patrick Maher, Robert Schwartz, Julius Sensat, James Van Aken, and, especially, Joan Weiner for criticism of earlier drafts of this paper. I have also benefited from conversations with Isaac Levi, David Lewis, and Edward McClennan.