 Perry 1977 argues that once we accept the distinction between belief states and belief contents, we should see that one can rationally believe a proposition and its negation by being in “distinct” belief states. Lois simultaneously believes that Superman is strong and that Superman is not strong. This does not call her rationality into question, as she believes the first proposition by being in a belief state properly related to ‘Superman is strong’ and believes the second by being in a belief state properly related to ‘Clark Kent is not strong’. Irrationality is believing a proposition and its negation in virtue of being in the same type of state, not merely believing a proposition and its negation.