Handbook of the History of Logic: - Fordham University Faculty

The Development of Supposition Theory in the Later 12 th through 14 th Centuries 213
Some animal can be grey
No donkey can be a stone
He can be grey
3. Combining a modal adjective with the copula
The third sort is more complex, with a syntax different from that of English.
Here a modal adjective together with a new copula combines with the existing
copula, which assumes its infinitive form. The subject and predicate terms
also take the objective case. Transliterations of some Latin examples are:
Some animal possible is be grey
No donkey possible is be a stone
Him possible is be a stone
An almost English analogue made by rearranging the words and inserting
‘to’ before the infinitive gives
Some animal is possible to be grey
No donkey is possible to be a stone
Him is possible to be a stone
Klima points out that this is acceptable English if you change ‘possible’to
‘able’:
Some animal is able to be grey
No donkey is able to be a stone
Him (he) is able to be a stone
The syntax is important, and so I will use a transliteration of the Latin
forms, preserving the Latin word-order.
My own opinion is that examples of type (3) are really accusative-infinitive constructions
with raised subjects, as evidenced by the accusative case of their subjects,
and they should be seen as special cases of type (2) above. But this is not
the way that Buridan (and probably others) viewed them. So I will treat them as
special cases of genuinely modal propositions. These three forms are spelled out
in the next section.
5.3.2 Modal Propositions — Semantics
What are the truth conditions for complex modal (alethic) propositions? Discussion
in medieval texts leaves the truth conditions for alethic modal propositions
somewhat unclear. The unclarity that we face here has to do with the logical forms
of such propositions. One option works fairly clearly, and matches most of the discussion
in the texts. This is, roughly, to make modal propositions look as much
like temporal ones as possible. In particular, in modal propositions we assume
that the copula itself is unaffected by the modal sign, and the terms themselves
are ampliated to possible things, or to necessary things. In particular: