The contrast between "subject and predicate" is a significant one in at least four different realms of discourse: grammar, epistemology, logic, and metaphysics. A large number of philosophical problems have to do with how the distinction on one level is related to that on some other level; whether there really are four such distinct realms and, if so, how they bear on one another are matters of controversy.

Grammar

In the realm of grammar, subject and predicate are sentence parts; they are, therefore, words or groups of words, and their definition and identification is a matter of syntax. In the simplest case, where the sentence consists of just two words, such as
(1)    � 0A0;Bats fly,
(2)    � 0A0;Fraser swims,
the subject is the noun and the predicate is the verb. Very few sentences are so simple, but an indicative sentence with just one...