Abstract

A scientific dispute may turn crucially upon whether or not a given hypothesis is ad hoc. So, it is extremely important to determine what makes a hypothesis ad hoc. Yet, previous accounts have failed, either because they have run afoul of the Quine-Duhem problem, or because of other major defects.I develop a novel account of ad hocness. I propose that a hypothesis is ad hoc when disconfirming evidence leads scientists to accept that hypothesis into their theory even though the core of the theory, in combination with auxiliaries and the evidence, does not entail the hypothesis.