Copula. The part of a proposition, be it one word or more, which
connects or couples the subject and the predicate.
In the modern languages, when propositions are stated in pure logical
shape, the part of the copula is generally performed by the verb
substantive, "Man is fallible." By Aristotle a logical proposition is
generally expressed thus: τὸ A ὑπἀρχει
παντὶ τῷ B, though he has other
ways of indicating it.
The copula me saltem judice is of no account in pure logic, is no real
element in the judgment or proposition. That I think consists merely of
the two terms, subject and predicate, and all that is wanted, and that
by no means universally, is some symbol, it may be algebraic, to
indicate their connection, and their quality, positive or negative.
The copula, however, is not viewed thus by all logicians. Some
consider the quality of the proposition to have its seat there, in which case of course it is a
matter of pure logic; others consider modality to be expressed by it, a
notion to which the Greek gave birth more naturally than do the
languages of modern Europe. See