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It may mean either of two things: either that x presupposes, in the sense that x requires y by a specific and definite necessity: or that x anticipates y, in the sense that x requires y by only a generic and indefinite necessity. (Perhaps another way of explaining what is meant by the two things that implication may mean-- i.e., presupposition and anticipation--is to say that, whereas the implication rightly distinguished as "presupposition" is unconditional, the implication rightly distinguished as "anticipation" is conditional.)

7 October 2008; rev. 15 August 2009