Handbook of the History of Logic: - Fordham University Faculty

Logic in the 14 th Century after Ockham 465
had determinate or merely confused supposition.
A different approach to the same issue can be found for example in the writings
of the early 17th century philosopher and theologian John of St. Thomas
(admittedly a few centuries off our period); 30 there, one finds a precise account
of the effect of distributive terms (the negation in particular) upon terms already
having confused and distributive supposition. For this purpose, one has to consider
the whole propositional context, i.e. the supposition of the other term in the
proposition. Here is how John formulates it: If two universal signs simultaneously
affect the same term, then you must see how it remains after the first negation
or universal sign is removed; and if it remains distributive with reference to a
term having determinate supposition, then it originally had confused supposition;
if however the term remains distributive with reference to a term having confused
supposition, it originally was determinate. [John of St. Thomas, 1955, 69]
Here are his own examples: ‘For example, if I said, No man is not an animal,
then when the first negative, i.e. the no, is taken away, animal becomes distributive
with reference to man, which is determinate. Thus originally animal had confused
supposition. However, if I said, Not every man is an animal, then when I take the
not away, man becomes distributive with reference to animal which is confused.
And thus man originally had determinate supposition.’ [John of St. Thomas,
1955, 69]
Making use of the symbolism introduced here, these rules can be formulated as:
Rule 3o ′ Dist(A)P & Conf(B)P &〈∼,A〉P∗ → Det(A)P ∗
Rule 3b ′ Dist(A)P & Det(B)P &〈∼,A〉P∗ → Conf(A)P ∗
If a uniform account of the effect of distributive terms upon terms already
having distributive and confused supposition could not be provided, this would
have been a serious drawback for theories of supposition as a whole. Seemingly,
at the time of Ockham and Buridan a solution for this issue had not yet been
found; however, later authors such as John Dorp and John of St. Thomas were
clearly aware of the problem, and succeeded in finding appropriate rules to deal
with it. Clearly, many other cases may seem problematic and appear to be, at first
sight, unaccountable for within supposition theory; but the reformulation of the
rules for confused and distributive supposition above shows that the supposition
framework is more resourceful than one might expect at first sight, allowing for
constant refinement. 31
30But this approach was already known in the 15th and 16th centuries, see [Ashworth, 1978,
600].
31See (Klima and Sandu 1991) for the use of supposition theory to account for complex quantificational
cases.