  Sylvan’s program was left unfinished when he died. Whatever one thinks of his bold statements (“a wild mixture of wonderfully incisive ideas and absolutely false claims,” as Meyer put it in 1996), Sylvan pushes philosophers to recognize that many propositions taken as facts are not unrestrictedly true, but rather are relative to what assumptions one is making about logic, ontology, and value. Changing those assumptions changes the possibilities. And Sylvan’s work urges us to be ready for more possibilities—even what is, as he put it, “beyond the possible” (this is the title of an unpublished manuscript cited in Routley 1980).