Abstract
It is often observed that explanatory reasoning, especially the so-called inference to best explanation, plays a crucial role in theory choice in scientific practice. This paper defends an alternative account of the justificatory role of explanatory reasoning in general, and IBE in particular, inspired by C.S. Peirce's account of abduction. Most contemporary proponents of IBE take it to provide justification for accepting hypotheses as true. In contrast to this, the Peircean view defended here takes explanatory reasoning to first and foremost provide justification for pursuing hypotheses, i.e. to subject them to empirical testing. The standard view of IBE faces a problem of accounting for the connection between explanatoriness and truth-likeliness : Why should the fact that a hypothesis would be a good explanation if it were true give us any reason to regard it as actually true? The Peircean view avoids this problem since justification for pursuing a hypothesis H does not require showing H any more probable. Furthermore, the Peircean view faces no analogous challenge: I develop an account of pursuit where the connection between explanatoriness and justification for pursuit is simple and intuitive. Briefly: assuming that one important goal of science is to find good explanations, showing that H would provide a better explanation than previously thought also shows that it would be more valuable to learn whether H is actually true, thus increasing the justification for pursuing H. Finally, the Peircean view provides an alternative account of the role played by explanatory reasoning in many of the historical case studies cited by proponents of IBE. This undermines historical-empirical arguments for the reliability of explanatory reasoning as a guide to true hypotheses.