Permissivism is the view that a single body of evidence can sometimes rationalize incompatible doxastic attitudes – for example, suspension of judgment and belief – toward some hypothesis. Impermissivism, by contrast, is the view that there is at most one rational doxastic response to the evidence. This dissertation argues that rationality is permissive, but in an unexpected way: cases in which a body of evidence rationalizes multiple, incompatible responses are possible, but subjects who are in such a case can never rationally believe that they are. This view has sometimes been referred to as unacknowledged permissivism. Unacknowledged permissivism is often said to be implausible. The orthodox view is that it is an unmotivated view, in par...