In this case, the string is it proved is a subject-auxiliary inversion of it is proved, which is a combination of dummy it with the simple passive is proved. The dummy subject it is inserted during extraposition, taking the place of the content clause, which is moved to the end of the sentence:
[That X is true] is proved. → It is proved [that X is true].
We can contrast the simple is proven with the perfect has been proved:
[That X is true] has been proved. → It has been proved [that X is true].
There's one complication: this particular verb has two past participles, proved and proven. That means we can write any of the following:
simple passive perfect passive
--------------------- -------------------------
It is proved It has been proved
It is proven It has been proven
All of these are grammatical, and the proved and proven versions are equivalent. The real question isn't proved versus proven, but simple versus perfect. Even though both versions are grammatical, they aren't used in the same situations. The simple version is used when I am talking about where something is proved, in a conditional, or (rarely) if something is proved right now.
- "Where is the theorem proved?" "It is proved in Appendix B."
- "If and when the theory is proven, you'll get your grant money."
- "It will be proved in five seconds. Five. Four. Three. Two. One. It is proven." (spoken, rare)
The perfect version is used when you're talking about something proved in the past, or whether something has been proven in the past:
- "I'm not sure if this is a good idea." "Don't worry, it's been proven to work."
- "The Theory of Evolution has been proven."
- "Has it been proved that the United States didn't have a third atomic bomb to drop over Japan?"
Note that outside of this context, proved and proven aren't always equivalent. Proven is favored in attributive uses (a proven fact, not *a proved fact) and in certain set phrases (innocent until proven guilty). The preterite is always proved, not proven (I proved him wrong, but never *I proven him wrong).
In this case, I agree with the edit. The change to proven is perhaps unnecessary, but to my ear it sounds better, so I don't object to that, either. Has it been proved would also be fine.
Not being fully aware of your intention with the sentence (there are some parts which are ambiguous), I agree that it is grammatical. (You do have a few words that repeat , you could re-order the clauses to flow better, and there are synonyms that you could use to shorten parts of it.) However, the main reason why you may be having a problem with it is because of how it "looks". The only punctuation that you use, other than a period, is the comma.
Feel free to avail yourself of the more than a dozen of other marks that you may use to make your sentence easier to read. For example:
From this:
"On other other hand, Common Law, which at this point has infiltrated the scene, would, as we can gather from from Littleton’s writing, deem the contract against the law and therefore void."
To this:
"On other hand, Common Law (which at this point has infiltrated the scene) would, as we can gather from Littleton’s writing, deem the contract against the law and therefore void."
Or this:
"On other hand, we can gather from Littleton’s writing that Common Law (which at this point has infiltrated the scene) would deem the contract unlawful and therefore void."
Hope this helps.
Best Answer
I think your instinct is correct.
To begin with, you can't say many others and I because other has to have an antecedent to distinguish itself from. You leave the hearer wondering "many other than who?"
But both many people and I and I and many people sound almost as odd. I suggest—and this is nothing more than a guess—that this is because employing a conjunction implies that many people and I are two different sorts of entity: you are distinguished from many people and consequently must be something other than a person. I and many others avoids this implication; but If you want to put the many in first place you're going to have to say something like as many people, including me, have said.