Handbook of the History of Logic: - Fordham University Faculty

212 Terence Parsons
In both of these cases the modality is predicated of what Buridan and others
called a dictum — roughly, of “what is said”. In the last two propositions this
is clear. These are the sorts of propositions in which a subject or a predicate
consists of a sub-clause which apparently supposits for a proposition. These are
really assertoric propositions; they predicate a modal predicate of a proposition
or propositions, but their own copula is unaffected and so they are not genuinely
modal. It is not clear exactly how to formulate a semantics for the first examples
with modal adverbs, but they seem to be exact parallels of the second sort. If you
change the adverb to the corresponding adjective plus copula, and make the rest
of the sentence into a sub-clause, you get propositions of the second sort. The
main clause then contains a newly introduced copula which is itself unaffected by
the modal words in the proposition.
We already have a syntax and semantics for the next-to-last proposition. For
example:
That every donkey is an animal is necessary
is true iff there is a mental proposition of the form
every donkey is an animal
which is necessary. (Whether such a proposition is necessary or not depends in
part on one’s metaphysical views. Presumably the proposition just given is not
necessary because it has existential import, and so it is false if no donkeys exist.)
Kind 3: Modal Propositions
A real modal proposition is one in which a modal word applies to the copula.
These come in at least three varieties.
1. Modal adverbs modifying the copula alone
The least-discussed cases are ones in which a modal adverb or prepositional
phrase directly modifies the copula with no other effect on the sentence.
Such cases look just like the first class under (2) except they are to be read
with the modal expression applying to the copula instead of applying to the
whole proposition. Examples are:
Some animal possibly-is grey
Every donkey necessarily-is an animal
Every donkey of-necessity-is an animal
He possibly-is grey
2. Combinations with the helping verb ‘can’
The second class uses the verb ‘can’(’potest’) as a helping verb with the
copula. The copula takes its infinitive form; otherwise there is no effect on
the rest of the expression. Cases of this sort are: