 For convenience, approaches to modeling doubt about one’s own ability to judge and to the five questions above can be separated into four types, which are overlapping and complementary rather than inconsistent. One approach is through seeing the self-doubting subject as believing epistemically unflattering categorical statements about the relation of her beliefs to the world. Another is through conditional principles, asking what a subject’s credence in q should be given that she has a particular credence in q but thinks she may be epistemically inadequate or compromised. A third approach is to construe doubt about one’s judgment as a matter of respecting evidence about oneself and one’s evidence (higher-order evidence). A fourth approach ties together the first order and second order by using the idea that we should match our confidence in p to our expected reliability. That is, treating ourselves like measuring instruments we should aim to be calibrated.