Abstract

The Uniqueness thesis says that any body of evidence E uniquely determines which doxastic attitude is rationally permissible regarding some proposition P. Permissivists deny Uniqueness. They are charged with arbitrarily favouring one doxastic attitude out of the set of attitudes they regard as rationally permissible. Simpson claims that an appeal to differences in cognitive abilities can remove the arbitrariness. I argue that it can't. Impermissivists face a challenge of their own: The problem of fine distinctions. I suggest that meeting this challenge requires impermissivists to loosen up at higher levels – when comparing belief-forming systems that differ in the fineness of their doxastic outputs. This more relaxed take on Uniqueness is a kind of ‘intraspecies impermissivism’.