Confirmation and Induction Jan Sprenger∗ Abstract Scientific knowledge is based on induction, that is, ampliative inferences from experience. This chapter reviews attacks on and defenses of induction, as well as attempts to spell out rules of inductive inference. Particular attention is paid to the degree of confirmation of a hypothesis, its role in inductive inference and the Bayesian explications of that concept. Finally, the chapter compares Bayesian and frequentist approaches to statistical inference. Keywords: confirmation, degree of confirmation, induction, probability, inductive logic, Bayesianism, statistical inference. ∗Contact information: Tilburg Center for Logic, Ethics and Philosophy of Science (TiLPS), Tilburg University, P.O. Box 90153, 5000 LE Tilburg, The Netherlands. Email:
[email protected]. Webpage: www.laeuferpaar.de 1 1 The Problems of Induction Induction is a method of inference that aims at gaining empirical knowledge. It has two main characteristics: First, it is based on experience. (The term “experience” is used interchangeably with “observations” and “evidence”.) Second, induction is ampliative, that is, the conclusions of an inductive inference are not necessary, but contingent. The first feature makes sure that induction targets empirical knowledge, the second feature distinguishes induction from other modes of inference, such as deduction, where the truth of the premises guarantees the truth of the conclusion. Induction can have many forms. The most simple one is enumerative induction: inferring a general principle or making a prediction based on the observation of par- ticular instances. For example, if we have observed 100 black ravens and no non-black ravens, we may predict that also raven #101 will be black.