Given a conditional P → Q, the consequent Q is said to be a *necessary* condition for the antecedent P — Q must be true whenever P is true, so Q's truth is necessary for P's truth. Equivalently: 'P only if Q.' Dual to sufficiency — if P is…
Given a conditional P → Q, the consequent Q is said to be a *necessary* condition for the antecedent P — Q must be true whenever P is true, so Q's truth is necessary for P's truth. Equivalently: 'P only if Q.' Dual to sufficiency — if P is…