The relationship between a set of premises and a conclusion when the conclusion follows from the premises, or may validly be inferred from the premises. Many philosophers identify this with it being logically impossible that the premises should all be true, yet the conclusion false. Others are sufficiently impressed by the paradoxes of strict implication to look for a stronger relation, which would distinguish between valid and invalid arguments within the sphere of necessary propositions. The search for a stronger notion is the goal of relevance logics.