In an inductive inference, we acquire a belief on the basis of evidence that is less than conclusive. The new belief is compatible with the evidence, but so are (possibly many) competing hypotheses that we are unwilling to infer. Such is the situation for a great number of the inferences we make, and this raises a question of description and a question of justification. What principles lead us to infer one hypothesis rather than another? And do we have any reason to believe that these principles are good ones, leading us to accept hypotheses that are true and to reject those that are false? Inference to the Best Explanation offers partial answers to both questions.

According to this model, explanatory considerations are a guide to inductive inference. We decide which of the competing hypotheses the evidence best supports by determining...