(Or "predicate calculus") An extenSIon of propoSItional logic with separate symbols for predicates, subjects, and quantifiers. For example, where propoSItional logic might asSIgn a SIngle symbol P to the propoSItion "All men are mortal", predicate logic can define the predicate M(x) which asserts that the subject, x, is mortal and bind x with the {universal quantifier} ("For all"): All x . M(x) Higher-order predicate logic allows predicates to be the subjects of other predicates. (2002-05-21)