  This section describes Sylvan’s work in logic. As in other areas of his philosophy, Sylvan was notable for his staunch defence of highly controversial and radical views—most strikingly, that classical logic is wrong, that non-classical logic is right, and that some contradictions may be true (see: dialetheism). What makes his work worth remembering is that he backed up such claims with rigorous (if contentious) arguments and mathematical details.