Abstract

The view that ‘ought’ cannot be deduced from ‘is’, credited to Hume as a major insight into the nature of morality, is surprisingly easy to refute. What they are doing is evil. Therefore, they ought not to do it. Here we have a case of deducing ‘ought’ from ‘is’. The conclusion follows, because ‘ought not’ is analytic to ‘evil’. ‘Ah, but that's just what is wrong with the example: the premise is not a pure “is”; it contains an “ought”, though this does not appear explicitly.’ This is true, of course; the inference would not be valid otherwise. Still, the example shows that the is/ought principle will not do as it stands