How do we go about weighing evidence, testing hypotheses, and making inferences? The model of "inference to the best explanation" (IBE) -- that we infer the hypothesis that would, if correct, provide the best explanation of the available evidence--offers a compelling account of inferences both in science and in ordinary life. Widely cited by epistemologists and philosophers of science, IBE has nonetheless remained little more than a slogan. Now this influential work has been thoroughly revised and updated, and features a new introduction and two new chapters. "Inference to the Best Explanation" is an unrivaled exposition of a theory of particular interest in the fields both of epistemology and the philosophy of science.