Barriers between you and I?

In "'Between you and I'" (10/5/2025), I quoted three theories that Merriam-Webster's Concise Dictionary of English Usage offers as possible explanations for the confusion over "between you and I" vs. "between you and me". The third of those theories cites Noam Chomsky, whose work is not usually part of usage discussion:

Another possible explanation (unnoticed by the comentaros) comes from the linguist Noam Chomsky. In his Barriers, 1986, he says that compound phrases like you and I are barriers to the assignment of grammatical case. This means that between can assign case only to the whole phrase and not to the individual words that make it up. Thus the individual pronouns are free to be nominative or objective or even reflexives. Chomsky's theory would also explain some other irregularities in pronoun use (See PRONOUNS); it's the best that has been offered so far.

I expressed skepticism about this theory, "for reasons to be discussed another time".

So now is another time, and here's the discussion.

The specific "between you and I/me" construction is not discussed anywhere in Barriers, as far as I can tell. More relevantly, I can't find any support in that work for the general idea that "compound phrases like you and I are barriers to the assignment of grammatical case."

And such a constraint would have been a problem for the theory. For example, in Latin, case assigned by prepositions is invariably spread across conjoined nouns, e.g. in Caesar's "inter Sequanos et Helvetios" or Horace's "ab Jove Neptunoque". Similarly, I think, in other languages with general morphological case-marking.

The work previously done by "barriers" is now the task of "phases", and I'm not up to date with the current epoch of this constantly-evolving set of theories. So I asked a colleague who is.

He confirmed what I thought about the 1986 version of the theory, and the empirical problem for any version preventing case assignment in coordinations:

I can’t find any mention of case assignment by prepositions to a coordination of one or more NPs (as in between you and I/me) in Chomsky 1986. So this seems like a misattribution at best. Furthermore, I don’t think Chomsky claims anywhere that coordinate structures are barriers, so it’s not obvious that he would have predicted any issue with a case assigner like P assigning case to each of the conjuncts.

Such shielding would be possible if &P (the coordination phrase, e.g., [you and I]) were a barrier or, in more modern theorizing, a phase, since syntactic operations like case assignment cannot take place across barriers/phases.

But, as you point out, in languages like Latin, case is assigned (obligatorily, I would suspect) in parallel to all coordinands in a coordination. So, empirically it seems that we don’t want to (always) shield coordinands from case assignment by a case assigner outside &P.

He then went on to offer some insights about the issue, with citations:

That being said, case in English is tricky, especially when it comes to coordinations. While non-coordinate pronominal subjects of finite sentences are always (in colloquial and formal registers/varieties) nominative (1), coordinate pronominal subjects are, in non-prescriptive varieties, typically objective (2).

(1) She already left. (2) [Jack and {her/*she}] already left. (non-prescriptive register/variety)

This speaks against the conclusion in the quoted Merriam-Webster passage that, roughly, ‘anything goes,’ since there is a clear preference in (2) (for many speakers) for the objective form and not the nominative (or reflexive) form.

Now, there is work (by Chomsky, Joe Emonds, and Nicholas Sobin) on the forms of pronouns in coordinations, and I believe all of them take nominative forms in such contexts (e.g., [you and I]) to be forced by prescriptive norms. One possible indication that regular case assignment (or its absence) is not at fault in the between you and I examples is that, at least for me, apparent ‘nominative’ case assignment is restricted to the second conjunct in such cases:

(3) All debts are cleared between [{her/*she} and I]. (marked)

I simply cannot have she as the first conjunct in (3); between her and I is acceptable, if marked (as indicated). So, whatever mechanism determines the form of English pronouns in coordinate structures probably shouldn’t be the same mechanism that assigns case in parallel to all members of an &P in Latin, etc. Sobin (1997) argues that the above use of … and I in English be handled with a special, extra-grammatical rule that essentially changes the case form of the pronoun in particular contexts (largely determined by prescriptive norms). While that may work for present-day English, of course, this doesn’t account for the use in Shakespeare’s English…

The cited works, all well worth reading, are:

Gary Olson, Lester Faigley and Noam Chomsky, "Language, Politics, and Composition: A Conversation with Noam Chomsky", Journal of Advanced Composition 1991. (see p. 31)

Joseph Emonds, "Grammatically Deviant Prestige Constructions", A festschrift for Sol Saporta 1986.

Nicholas Sobin, "Agreement, Default Rules, and Grammatical Viruses", Linguistic Inquiry 1997.

Here's the abstract from Sobin 1997:

Certain constructions of prestige English, including nominative Case in coordination and plural agreement in expletive constructions, pose difficulties for speakers of English uncharacteristic of normal linguistic constructions. Assuming the Minimalist Program, these linguistically deviant constructions (Emonds 1986) form a structurally coherent group exhibiting signature characteristics including lexical specificity and insensitivity to certain phrasal constituents. Such constructions are argued to be the product of grammar-external rules called grammatical viruses. Virus theory offers an explanation within minimalist assumptions of how "editing" toward such prestige constructions takes place in derivation and of why such constructions are difficult to acquire and control.

Google Scholar lists 322 citing works, and a theory of grammatical viruses strikes me as a good way to think about (some kinds of) prescriptive intrusions — but again, how could Shakespeare have been infected?

Emonds 1986 takes a similar view:

[S]ociological and linguistic evidence shows that the standard or prestige usage is not a grammatical construct, but an extra-grammatical deviation imposed in certain, especially written forms of language exclusively through para-linguistic cultural institutions of the dominant socio-economic class: exclusive and higher education, standard reference handbooks for business and journalism, paid or unpaid secretarial help, ghost writers, etc.

The evidence is convincing, overall, though such paralinguistic imposition is again not very plausible in the 16th century.