H. P. Grice: It might be that either generally or at least in special contexts it is impossible for a rational speaker to employ the conditional form unless, at least in his view, not merely the truth-table requirements are satisfied but also some strong connection holds. In such a case a speaker will nonconventionally implicate, when he uses the conditional form in such a context, that a strong connection does hold.

It might be that either generally or at least in special contexts it is impossible for a rational speaker to employ the conditional form unless, at least in his view, not merely the truth-table requirements are satisfied but also some strong connection holds. In such a case a speaker will nonconventionally implicate, when he uses the conditional form in such a context, that a strong connection does hold.