‘Ought Implies Can’: Not So Pragmatic After All

Those who want to deny the ‘ought implies can’ principle often turn to weakened views to explain ‘ought implies can’ phenomena. The two most common versions of such views are (a) that ‘ought’ presupposes ‘can’, and (b) that ‘ought’ conversationally implicates ‘can’. This paper will reject both views, and in doing so, present a case against any pragmatic view of ‘ought implies can’. Unlike much of the literature, I won't rely on counterexamples, but instead will argue that each of these views fails on its own terms. ‘Ought’ and ‘can’ do not obey the negation test for presupposition, and they do not obey the calculability or the cancelability tests for conversational implicature. I diagnose these failures as partly a result of the importance of the contrapositive of ‘ought implies can’. I end with a final argument emphasizing the role the principle plays in moral thinking, and the fact that no pragmatic account can do it justice.