Published online by Cambridge University Press: 28 February 2022
Here follows a puzzle for those attempting to explain inductive inference. Suppose one hypothesis, H, implies another, I. Suppose further we obtain evidence, E, deemed sufficient to warrant the rejection of I. Is this evidence sufficient to warrant the rejection of H as well?
It is very tempting to answer this question affirmatively. The inference in question appears to be justified by a single use of modus tollens or denying the consequent:
A testament to the obvious plausibility of this sort of inference is the ubiquity of its endorsement in treatises on inductive inference. See, for example, Popper (Popper 1935, p. 76), Hempel (Hempel 1945, p. 31), Hacking (Hacking 1976, p. 33), or Savage (Savage 1954, p. 32). Indeed, a referee reporting on another paper called the following “rule of implication”:
(+) If hypothesis H implies hypothesis I, then evidence sufficient to warrant the rejection of I, in turn warrants the rejection of H.