Handbook of the History of Logic: - Fordham University Faculty

206 Terence Parsons
makes no difference — and you end up with a complex term suppositing for grey
donkeys. 58 Since the issue of restriction by modification has no effect on the truth
conditions of sentences containing modified terms, I’ll ignore this complexity.
5.2 Ampliation and Restriction by Tenses
5.2.1 A rejected view
Some writers begin their discussion of ampliation caused by tenses by rejecting a
view that must have been widely discussed, if not widely held. This is the view
that:
A past tense proposition is true now iff its present tense version was
true sometime in the past.
On this view, ‘A donkey was grey’ istruenowiff‘A donkey is grey’ once was true.
This theory is easily shown false by examples like:
A white was black
This is true if something that is now white was black in the past. And this is so
even if the present tense proposition:
A white is black
was never true. 59 A similar example for the corresponding modal case is:
A white can be black
which has a true reading, even though
58Some authors said that as a consequence of such restriction, a word like ‘risible’ “alienates”
the supposition of ‘donkey’ in:
Every risible donkey is running.
It makes it supposit for nothing. Again, the important point is that the complex subject ‘risible
donkey’ supposits for nothing, and it doesn’t matter whether this is because the intersection of
risible things with donkeys is empty, or because the intersection of risible things with no things
at all (that is, with risible donkeys) is empty.
59In discussing the future tense Buridan says (SD Sophismata 4 (881): And from these [considerations]
there follows an important point: it is not required for the truth of a past or future
tense proposition in which the subject is appellative that the corresponding proposition in the
present tense be true sometime in the future. This is so, even assuming that such a proposition
will always exist in the future. Here by “corresponding proposition”, I mean one that has
the same subject and predicate, for although ‘[A] white [thing] will be black’ is true, because
it is equivalent to the true [proposition] ‘What is or will be white will be black’, nevertheless,
‘[A] white [thing] is black’ will never be true, even if it should be uttered. But in reducing a
future tense proposition to a present tense proposition, it is necessary to remove the appellation
from the subject of the proposition and it is necessary to change the appellative subject into a
non-appellative subject that supposits for what the appellative subject supposited for, and in
respect of which the proposition was true; as when, pointing to [that thing], we were to change
the subject into the pronoun ‘this’, and say ‘This is white’, and then it is necessary that, if
the future tense proposition was true, then a present tense proposition of that sort will be true
sometime.