Handbook of the History of Logic: - Fordham University Faculty

The Assimilation of Aristotelian and Arabic Logic up to the Later Thirteenth Century 305
4.2 The De interpretatione
The De interpretatione commentary of Kilwardby in the same series of lectures as
mentioned above is also very interesting. Aristotle begins his work by saying that
“spoken words are signs of mental affections and written words are signs of spoken
words.” These lines were very influential and Kilwardby starts his commentary by
expanding on them. Thought are likenesses of reality, he claims, and he identifies
the meaning (signification) of an utterance with the intelligible species (form) in
the intellective soul. It is hence the form in singulars or the essence in reality that
correspond to the meaning of words.
In his comments on predication in the De interpretatione commentary, he explicitly
compares predication, that is, the relation between the subject and the
predicate, with the relation between form and matter. He uses the terminology
‘forma predicati’ or ‘the form of the predicate’ to explicate how the predicate inheres
in the subject. The proposition ‘Socrates in white’ is true because whiteness
inheres in Socrates, and in the linguistic expression the ontological relation is mirrored.
As the form of white informs a substance or matter the predicate informs
the subject. The whiteness in Socrates is an accidental form, since he in only
contingently white, so the predication expressing this truth is only an accidental
predication, but supposedly in regards to essential or substantial forms the corresponding
predication is essential or substantial, as in ‘A human being is rational’,
since ‘rational’ is in this case a reference to the human soul. Kilwardby brings
these thoughts into his analysis of Aristotle’s modal syllogistics as well (see the
discussion below).
One of the most interesting and also one of the most discussed parts of Aristotle’s
De interpretatione is, of course, Chapter 9. Albert the Great’s and Thomas
Aquinas’ treatments of this chapter in their respective commentaries are very similar
and obviously influenced by Averroes discussion in his middle commentary
on De interpretatione. 59 I will here present some of the most interesting parts of
Aquinas’ discussion.
In Lectio 13, Aquinas begins by dividing propositions (enuntiationes). The first
division is according to unity, that is, into simple and conjunctive propositions;
the second division is according to quantity, that is, into affirmative and negative
propositions; the third division is into quality, that is, into universal, particular,
indefinite and singular propositions. The forth division is according to time and
then propositions divide into propositions about the past, present and the future.
The fifth and final division is in regards to matter. The matter of a proposition is
taken from the relationship of the predicate to the subject. If the predicate is per
se in the subject, then the proposition is said to be in necessary or natural matter.
The examples he gives are ‘A human being is an animal’ and ‘A human being is
risible’. The the first case the relation is a genus to a species and in the second it
is a property (proprium) to a species. If the predicate is repugnant of the subject
as in ‘A human being is an ass’, then the proposition is in impossible or remote
59 See [Knuuttila, 2006].