Handbook of the History of Logic: - Fordham University Faculty

402 Gyula Klima
it is a substantial or an accidental actuality, this is why when we want
to signify any form or act to actually inhere [inesse] in a subject, we
signify this by means of the verb ‘is’, either absolutely [simpliciter] or
with some qualification [secundum quid] ... 26
That is to say, according to Aquinas, the reason why we use the verb signifying
existence to indicate the application of the predicate to the subject is precisely
because in any act of predication we actually predicate existence: either the existence
of the thing supposited for by the subject absolutely, or the existence of the
form signified by the predicate in the subject.
Thus, the copula with respect to a suppositum of the subject and with respect to
the ultimate significatum of the predicate in that suppositum signifies the existence
of this ultimate significatum, which can be compositionally determined as the value
of the signification of the verb ‘is’ and its equivalents. However, depending on the
nature of the ultimate significata of the predicate, the existence of these ultimate
significata may be radically different. This is the clearest in the case of the ultimate
significata of a privative predicate, such as ‘blind’, and the corresponding positive
predicate, such as ‘sighted’. Clearly, for the ultimate significata of ‘blind’ to exist
is for the ultimate significata of ‘sighted’ not to exist. Therefore, since nothing can
be existence and non-existence in the same sense, we cannot say that in ‘Homer
is blind’ and ‘Socrates is sighted’ the copula would signify existence in the same
sense. So, the significata of the copula in respect of the ultimate significata of the
predicates of these sentences in the supposita of the subjects cannot be said to be
acts of existence in the same sense.
However, at the same time, with regard to the immediate significatum of the
predicate (the common nature signified by the predicate) the copula also signifies
the existence of some other type of entity uniformly, in the same sense, according
to Aquinas, namely, of the entity signified by the proposition as a whole, the
so-called enuntiabile. 27
The conception of propositional signification involving such entities crops up
quite early in the history of medieval logic, and recurs in different guises time and
again. 28 It is present in Abelard’s theory of dicta, and it is worked out in greater
detail by the anonymous author of the 12 th -century tract Ars Burana as follows:
Note that whether we speak about the dictum of a proposition or of the
significate of a proposition or of an enuntiabile it is the same. For an
enuntiabile is what is signified by a proposition. For example: ‘A man
is an animal’, this proposition is true, because what it signifies is true;
26 In Perihermeneias lb. 1, lc. 5, n.22
27 For a detailed reconstruction of Aquinas’ ideas on the signification of the copula along these
lines, see Klima, G. “Aquinas’ Theory of the Copula and the Analogy of Being”, Logical Analysis
and History of Philosophy, 5(2002), pp. 159-176.
28 Cf. Nuchelmans, G. Late Scholastic and Humanist Theories of the Proposition, Amsterdam:
North Holland Publishing Co., 1980, and Theories of the Proposition: Ancient and Medieval
Conceptions of the Bearers of Truth and Falsity. Amsterdam: North Holland Publishing Co.,
1973. Perler, D. “Late Medieval Ontologies of Facts”, The Monist 77(1994), pp. 149-169.