 ‘I am a poet but I do not know it’ expresses a proposition I cannot know.  But I can reach the proposition by other attitudes such as hoping and wishing. A blindspot for a propositional attitude is a consistent proposition that cannot be accessed by that attitude. Blindspots are relative to the means of reaching the proposition, the person making the attempt, and time at which he tries. Although \(I\) cannot rationally believe ‘Polar bears have black skin but I believe they do not’ you can believe that I mistakenly believe polar bears do not have black skin. The evidence that persuades you I am currently making that mistake cannot persuade me that I am currently making that mistake. This is an asymmetry imposed by rationality rather than irrationality. Attributions of specific errors are personal blindspots for the person who is alleged to have erred.