Abstract

Hume’s familiar sceptical argument against induction brands as irrational our practice of generalising from observed regularities because of its reliance on the assumption that nature is uniform, an assumption which is unjustifiable. The argument which I wish to consider focuses instead on the observed regularities that are required if we are legitimately to extrapolate from experience. According to Hume, the paradigm type of inductive reasoning involves a constant conjunction. But in fact we do not encounter such invariable uniformities: our experience is, almost invariably, irregular. So setting aside Hume’s sceptical qualms about the very attempt to form expectations about the hitherto unobserved, how can we justify our ignoring such irregularities? My conclusion is that, even if the principle of uniformity can be justified, our practice is irrational by Hume’s lights. This is a new Humean critique of our “causal reasoning,” for, although Hume does not present it, the ingredients are all his.