Handbook of the History of Logic: - Fordham University Faculty

262 Terence Parsons
to formulate a proposition containing a term that works this way, using only the
terminology we have at our disposal. 125
Paul of Venice in LM divides distributive supposition into mobile and immobile.
His account of mobile supposition is interestingly different from earlier accounts.
He says that a term has mobile distributive supposition in a proposition if one may
descend under a term to a conjunction of instances of that proposition, and one
may also ascend — not from a single instance – but from the whole conjunction. 126
It is easy to check that the subjects of the standard universal propositions have this
kind of supposition, as well as the predicate of a universal negative proposition.
But the predicate of a particular negative proposition does not have this kind of
supposition, since you cannot go from
to
Some A is not this B and some A is not that B and ...and so on for
all the Bs.
SomeAisnotaB.
It is odd for him to call this “immobile” supposition, because one can descend
under the predicate term of a particular negative to any instance. Perhaps he sees
mobility as requiring a valid inference in both directions. We will return to his
particular kind of supposition in a later section. Meanwhile it appears that there
was a practical consensus on the account of distributive supposition simpliciter.
8.9.3 Merely Confused Supposition
We have been using this definition:
A term F has merely confused supposition in a proposition P if and
only if
[Descent]: you may not descend under F to either a conjunction
or a disjunction of propositional instances of all the F s,
and
[Ascent]: from any instance you may ascend back to the
original proposition P .
This mode shows the most variation in how it is characterized. I’ll look at two
options. The first is the most famous one, devised by Ockham, which invokes
125 Spade [1988] argues this, giving a clear explanation of what is at issue. (Trivial counterexamples
to the claim are ruled out by the policy of ignoring the effect of repeated terms in
testing for mode of supposition.)
126 Paul of Venice LM 3.11a (89-121): “Distributive general reference is twofold because some is
mobile, some immobile. Distributive mobile general reference is the meaning of a common term
beneath which one can infer to all of its singulars conjunctively on the condition of a proper
middle and, conversely, with the same middle.”