 Like the approach via the maximally rational agent, the evidential approach has the virtue of identifying a justification for responding to the second-order beliefs that self-doubt brings. Their authority comes from the facts that they are evidence relevant to whether one has good evidence for one’s first-order belief, and that one should respect one’s evidence. This raises the hope that what we already know about evidence can help settle when negative second-order evidence should override a first order belief and when not. Many authors have thought that in either kind of case rationality demands that the two orders eventually match, in some sense, but we will see below that more recent thinking about evidence has led some to defend the rationality of having the first- and second-order beliefs in tension, for some cases. Another virtue of the evidential approach is that merely knowing what your beliefs are doesn’t automatically imply that a state of self-doubt is inconsistent or incoherent as it did in first two approaches above, via categorical beliefs and conditional principles. There is no obvious contradiction in believing both q and that one’s evidence doesn’t support q, even if one also has a correct belief that one believes q, so what may be irrational about the state must be based on further considerations.