Handbook of the History of Logic: - Fordham University Faculty

306 Henrik Lagerlund
matter. If the relation is neither of these, then the proposition is in possible or
contingent matter. The way Aquinas outlines the modal propositions is very close
to the way Robert Kilwardby did it (see the discussion in the next section). 60
In necessary matter, universal propositions are determinately true, claims Aquinas,
and their negations are determinately false, since they are in impossible matter.
This holds for past, present as well as future tensed propositions. He then turns to
contingent matter and notes that all universal propositions are false in contingent
matter while particular and indefinite propositions are true for past, present and
future tensed propositions. The reason for this is reviled by the square of opposition,
since in a contingent proposition both the affirmation and negation are true
and that is impossible for universal propositions.
The problem for Aquinas is where to locate singular propositions in this division.
He writes:
In singular future propositions, however, there is a difference. In past
and present singular propositions, one of the opposites must be determinately
true and the other false in any matter whatsoever, but
in singulars that are about the future, it is not necessary that one
be determinately true and the other false. This holds with respect
to contingent matter; with respect to necessary and impossible matter
the rule is the same as in propositions about the present and the
past. Aristotle has not mentioned contingent matter until now because
those things that take place contingently pertain exclusively to singulars,
whereas those that per se belong or are repugnant are attributed
so singulars according to the notions of their universals. Aristotle is
therefore wholly concerned here with this question: whether in singular
propositions about the future in contingent matter it is necessary that
one of the opposites be determinately true and the other determinately
false. 61
For Aquinas this is the problem Aristotle addresses in Chapter 9. The rest of
Aquinas’ discussion is about whether singular contingent propositions about the
future are determinately true or false, or not. He explains the problem like this:
If it is necessary that every affirmation or negation about future singulars
is true or false, it is necessary that everyone who affirms or
denies, determinately says what is true and false. From this it follows
that it is necessary that everything be or not be. Therefore, if every
affirmation or negation is determinately true, it is necessary that everything
determinately be or not be. From this he concludes further
that all things are of necessity. That would exclude the three kinds of
60 See also [Knuuttila, 1981, 208-17; 1993, 129-32].
61 See Thomas Aquinas, Expositio peryermeneias, I.13, n. 6, for the Latin, and see [Oesterle,
1962, 103-4], for the translation. I have slightly modified it, though.