At the APA yesterday Jim Joyce gave an interesting talk on the future for inductive logic. Joyce argued that there is no future for it since there is no correct objective measure of confirmation. The goal of inductive logic is to characterize the inductive strength of arguments from some given evidence to a conclusion. This can be represented as a conditional probability, the probability of a hypothesis on a body of evidence—P(H/E1 & E2 & … & En). Joyce argues that even the clearest cases of inductive probability turn out to rely on a mistaken assumption. Here’s the case:
A ball will be drawn at random from an urn containing 100 balls.
Seventy-five balls are white and twenty-five are black.
—
A white ball will be drawn.
What is the degree of confirmation the premises provide for the conclusion? The intuitive answer is .75. Joyce argues, however, that this is mistaken because it relies on the principle of insufficient reason–treating equipossible outcomes as having an equal probability of occurring. (more…)