Copula
Copula
The traditional analysis of a proposition into subject and predicate involves a third part, the copula (is, are, is not, are not), binding the subject and predicate together into an assertion either of affirmation or of denial. It is now, however, commonly held that several wholly different meanings of the verb to be should be distinguished in this connection, including at least the followingpredication of a monadic propositional function of its argument (the sun is hot, 7 is a prime number, mankind is numerous); formal implication (gold is heavy, a horse is a quadruped, mankind is sinful); identity (China is Cathay, that is the sun, I am the State); formal equivalence (lightning is an electric discharge between parts of a cloud and the earth). — A.C.