Handbook of the History of Logic: - Fordham University Faculty

244 Terence Parsons
Every donkey is spotted.
Finally, merely confused supposition:
Merely Confused Supposition 101
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 about
all the F s, and
[Ascent]: from any instance you may ascend back to the
original proposition P .
The term ‘mammal’ has merely confused supposition in ‘Every donkey is a
mammal’ because:
Descent: You may not descend under ‘mammal’ in ‘Every donkey is
a mammal’ to either:
or to:
Every donkey is this mammal and every donkey is that mammal
and ..., and so on for all the donkeys
Every donkey is this mammal or every donkey is that mammal
or ..., and so on for all the donkeys.
Ascent: You may ascend back to the original proposition from any
instance. From:
101 The account given is that of Burley. Burley 1.1.4 para 85 (103): “Supposition is merely confused
when a common term supposits (a) for several things in such a way that (b) the proposition
is inferred from any one of them and (c) one cannot descend to any of them either copulatively
or disjunctively. The predicate supposits in this way in ‘Every man is an animal’, because: (a)
the term ‘animal’ supposits for several things. For if it supposited for some determinate one,
the proposition would be false. (b) The proposition is inferred from any of its singulars. For
it follows: ‘Every man is this animal; therefore, every man is an animal’. And (c) one cannot
descend under ‘animal’ either disjunctively or copulatively. For it does not follow: ‘Every man
is an animal’ therefore, every man is this animal or every man is that animal’. Neither does
it follow: ‘Every man is an animal; therefore, every man is this animal and every man is that
animal’, and so on.
Buridan agrees, but omits the ascent condition. Buridan 4.3.6 (264): “But merely confused
supposition is that in accordance with which none of the singulars follows separately while retaining
the other parts of the proposition, and neither do the singulars follow disjunctively, in terms
of a disjunctive proposition, although perhaps they do follow by a proposition with a disjunct
term.”
Ockham adds a condition on descent which will be discussed in section 8.9.3. Ockham I.70
(201): “Merely confused supposition occurs when a common term supposits personally and it is
not possible, without a change in either extreme, to descend to particulars by way of a disjunctive
proposition, but it is possible to descend by way of a proposition with a disjunctive predicate
and it is possible to infer the original proposition from any particular.”