ABSTRACT
Many attempts have been made to reduce ‘presupposes’ to ‘implies’; so as to make life easier for analysts, and also by way of defending the claim that certain two–valued calculi are adequate to express all logical relationships. The argument that true knowledge is infallible affirms the Antecedent, and moves ‘back’ to what is presupposed. The relations of presupposition, just reviewed, underly a surprising number of moves in current philosophical debate: surprising, because the relations themselves are often not distinctly recognized, but lumped in with others which are more familiar. Socrates used to test definitions by whether they fitted the admitted instances, and sometimes ended by discarding all the received accounts as inadequate: the accounts, not the concept they were failing to define. The cynic may well suppose that some people will blunder on with the exploded old morality, imagining that killing is ‘wrong’ and that health is somehow ‘good’.
