  Subjectivists maintain that beliefs come in varying gradations of strength, and that an ideally rational person's graded beliefs can be represented by a subjective probability function P. For each hypothesis H about which the person has a firm opinion, P(H) measures her level of confidence (or "degree of belief") in H's  truth.[6]  Conditional beliefs are represented by conditional probabilities, so that PE(H) measures the person's confidence in H on the supposition that E is a  fact.[7]