Presupposition and entailment (Q2560803)

Mitchell Ginsberg has recently argued that the traditional conception of entailment must be modified to allow for the fact that a statement having a presupposition can entail a statement not having the presupposition. Contending that the entailed statement may be false while the entailing statement is truthvalueless, Ginsberg suggests rejecting the traditional principle that if \(A\) entails \(B\), then if \(B\) is false \(A\) is false. Against Ginsberg it is argued that rejection of this principle has undesirable consequences, and that a satisfactory solution can be provided by modifying instead the conception of presupposition underlying Ginsberg's view. Rather than viewing a presupposition as a proposition whose truth is a necessary condition of the truth and of the falsity of the presupposing statement, it is suggested that we view a presupposition as a proposition whose truth is a necessary condition of the truth of the presupposing statement and of every logical compound statement containing the presupposing statement. lt is argued that by employing this conception we can explain the relevant phenomena while avoiding any clash with the traditional conception of entailment.