In the previous chapter, I argued that the doxastic state of accepting a hypothesis is not reducible to probability, and I sketched a Bayesian theory of rational acceptance that takes into account cognitive utilities as well as probabilities. But a theory of acceptance is not a usual component of Bayesian philosophies of science. It seems that many Bayesian philosophers of science think of subjective probability as a replacement for the notion of acceptance, and so think that acceptance has no important role to play in a Bayesian philosophy of science. This chapter will argue that that view is a mistake, by describing three ways in which the theory of acceptance makes an important contribution to Bayesian philosophy of science.

EXPLAINING THE HISTORY OF SCIENCE

Much of what is recorded in the history of science is categorical assertions by scientists of one or another hypothesis, together with reasons adduced in support of those hypotheses and against competing hypotheses. It is much less common for history to record scientists' probabilities. Thus philosophers of science without a theory of acceptance lack the theoretical resources to discuss the rationality (or irrationality) of most of the judgments recorded in the history of science. But a philosophy of science this limited in scope can fairly be described as impoverished.

Without a theory of acceptance, it is also impossible to infer anything about scientists' subjective probabilities from their categorical assertions.