Handbook of the History of Logic: - Fordham University Faculty

The Development of Supposition Theory in the Later 12 th through 14 th Centuries 207
A white is black
is not possibly true.
5.2.2 A Complexity — ambiguity or disjunction?
A sentence like ‘Some bishop was running’ can be true in two different ways. In one
way it is true if something that is a bishop now was running in the past, even if it
was not a bishop then. The other way is that something which may not be a bishop
now (indeed, may not even exist now) was a bishop in the past and ran in the
past. All theorists agree that there are at least these two options. They disagree,
however, about whether this is because the sentence is ambiguous between these
two readings (as Ockham says 60 ), or whether the sentence is unambiguous and it
has disjunctive truth conditions (as Buridan says 61 ), so that it is univocally true
in either of these cases. I don’t know how to choose between these options. For
simplicity, I will discuss the disjunctive truth condition option.
The proposition ‘A bishop was running’ must be made true by something that
ran in the past, not by something that only runs at present, so this dual interpretation
is not available for the predicate. So the subject and predicate of a
past tensed sentence are affected differently by the tense. The predicate is ampliated/restricted
so as to supposit only for things which it formerly signified. The
subject however is ampliated so as to supposit for things which it signifies now or
which it formerly signified.
5.2.3 Coordination of Tenses and Complex Terms
How tenses work in natural language is a complex matter, which is made difficult
by unclarity in the data — that is, unclarity due to speakers of the language not
associating clear truth conditions with tensed sentences. As a result, it is not
easy to assess the ultimate success of the medieval theory. It conflicts with some
standard paradigms of late 20 th century tense logic, but it is often not completely
clear which view better matches ordinary language usage. Since the intent is to
develop the semantics of a somewhat artificial regimented use of Latin, I will be
reluctant to draw many firm conclusions about its adequacy in terms of capturing
Latin usage.
Some complexities in how tenses work are discussed here.
5.2.4 Coordination of times between subject and predicate
I begin with what some may consider the clearest flaw in the simplest applications
of the account. Consider the sentence:
60 SL II.22 (158): “. . . every past-tense or future tense proposition in which the subject is a
commontermmustbedistinguishedasequivocal...Forifthepropositionispast-tense,then
the subject can supposit for that which is such-and-such or for that which was such-and-such.”
61 SD 4.5.2 (293): “. . . a term put before the verb appellates its form in a disjunctive manner,
for the present and for the tense of the verb”