  Sylvan’s work in logic can be viewed in part as a response to a wide range of paradoxes, such as the paradoxes of self-reference (like the Liar Paradox). He was equally focused on paradoxes of implication, and so was a leading developer of relevant logics, logics characterized by their concern that there be a meaningful connection between the antecedent and consequent of a conditional. These topics would lead him to be one of the founders of the so-called “Australasian school” of paraconsistent logic, logics that tolerate inconsistency without incoherence. He was perennially concerned with the universality of logic. Along with intrinsic interest, his logical research was always motivated by its eventual application to issues in metaphysics, ethics, and beyond.