Est . . . quae sunt . . .

Latin Learning Latin
1

In 1535, Agostino Nifo explains when we can draw a conclusion about all after observing only some:

“Est enim in propositionibus per se, quae sunt de omni dialectica,
quae est in propositionibus probabilibus,
et quoniam in talibus idem est iudicium de uno singulari, et de omnibus, ideo non oportet inducere in omnibus singularibus.”

In this field of Scholastic logic, propositions true per se are ones true in and of themselves. Propositions true de omni are true in all cases.

I expect Nifo to be saying something like

“What is true per se is also true de omni, that is, what one property is true of the class as a whole exists in each instance

—in dialectics, that is, which is about propositions that are [merely] probably.
And since in such cases the judgment about one particular and about all of them (de omni) is the same, it is not necessary to induce through all the particulars.”

How, literally, should I read “Est . . . quae sunt” at the beginning? Why a singular followed by plural?

What am I reading incorrectly?

(One later edition printed “de omni. Dialectica quae est″. Another printed “de omni dialectica inductio, quae est”.)

2

Well I’m no logician, but the way it looks to me, the initial est is not picked up by quae sunt, which just qualifies propositionibus per se, but by the succeeding quae est. “For there exists [among the per-se props that concern all dialectic] (one) which …”

And in the quoniam clause, the “et” in “idem est iudicium de uno singulari, et de omnibus” will mean it’s the same in a single individual case as [not “and”] in all. That’s just Latin.

And oportet doesn’t mean “it’s necessary”.

Any clearer now?

3

Thanks @mwh. On your reading, why is “quae est” feminine?

4

Because propositio is feminine.
In propositionibus est quae … (“there’s one which …”), cf. In hominibus sunt qui … (“there are some who …”).