  Sylvan’s thinking about contradictions evolved, depending on his co-author, even over the course of a book. In Relevant Logics and their Rivals (1982), early chapters float dialetheism as a hypothesis, in an “agnostic” spirit (61), or that of taking precautions; whereas later in the book, it states bluntly that “mathematics is inconsistent” (255). (The shift is criticized by Urquhart in a 1988 review (Brady 2003, 2).)