ones

[constantinusphilo]

We have also said in the inquiry that quantified propositions have a certain differentia with respect to unquantified.
Is it correct this way or should I add 'ones' after 'unquantified?'

 

[Barque]

Yes, I'd say you need "ones", though in a casual sentence you could probably drop it.

But the sentence needs other changes too.

We have also said in the inquiry that quantified propositions have a certain differentia with respect to unquantified.

We have also said in our findings from the inquiry that quantified propositions have certain differentia as compared to unquantified ones.

Note that "differentia" is a word you'd probably only find in academic writing. I can't recall having heard it before and had to look it up, and I'm not completely sure I've used it correctly.
We have also said in our findings from the inquiry that quantified propositions have certain characteristics that differentiate them from unquantified ones.
We have also said in our findings from the inquiry that quantified propositions have certain distinct characteristics as compared to unquantified ones.