Handbook of the History of Logic: - Fordham University Faculty

260 Terence Parsons
mode of supposition that it has in the original proposition. However, Ockham
limits this principle. In the paragraph following the cited one he says:
One might claim that a consequence of this analysis is that the subject
in ‘Only what is an animal is a man’ would not have merely confused
supposition. The point would be that since the proposition is equivalent
to a conjunction of propositions, one of which is affirmative and the
other negative, the subject would have a different form of supposition
in each of the elements of the conjunction. The response is that in the
exclusive affirmative proposition the subject has merely confused supposition,
for although the exponents of that proposition have subjects
with different forms of supposition, those subjects are not identical
with the subject in the original exclusive proposition; and because the
subjects of the affirmative and negative exponents differ from the subject
of the exclusive proposition, that subject can have one of the three
forms of proposition.
Probably Ockham has in mind expounding ‘Only an animal is a man’ as ‘An
animal is a man and every man is an animal’. Here the subjects are clearly not
the same, but it is not clear why that should yield any answer at all. I speculate
that Ockham’s policy is to try to apply the tests for supposition to the original
proposition, and if one of them works, then that settles the matter. If none of
them work, then the term has no mode of supposition. It is only in the latter
case that one looks for an explanation in terms of the term’s occurring twice in
the exponents of the proposition with different modes of supposition. What is
puzzling is why, if this is a good explanation, the same sort of explanation should
not be good in other cases.
8.9 Variant Interpretations of the Modes
I have been discussing certain definitions of the modes of personal supposition. No
one author used exactly these three definitions. Instead I chose them to represent
the “best of Burley-Ockham-Buridan”. In this section I discuss variant definitions.
8.9.1 Determinate supposition
We have used this version of determinate supposition:
A term F has determinate supposition in a proposition P if and only
if
[Descent]: you may descend under F to a disjunction of
propositional instances of all the F s, and
[Ascent]: from any such instance you may ascend back to
the original proposition P .