How do various frameworks account for situations when multiple cases can be assigned?

Question

1. My mother and I went to the market.

2. My mother and me went to the market.

Many (most?) English speakers today will accept both of these as grammatical. But it would be hard to argue that they represent different syntactic structures. So how do various linguistic frameworks account for situations like these in which multiple cases can be assigned?

Edit: There's quite a bit of discussion in the comments about what role case plays in English today, and what it would mean for cases to be fixed or not. When I asked this question I was thinking of case as an inflectional category which is applied to nouns (in English only pronouns) in certain contexts. The Nominative and Accusative cases do not have an intrinsic meaning connected with the subject or object, but get assigned to constituents according to various rules. Potential English rules could be:

1. Assign the nominative case to the subject constituent
2. Assign the accusative case to a noun following a conjunction
3. Assign the accusative case to all other nouns

Various frameworks would formulate these assignment rules in different ways, but I suspect they'd end up being quite similar in the end.

If the first example was ungrammatical these rules would suffice. But since it isn't, and if we don't consider there to be any evidence for different syntaxes, then can a list of rules like this allow for both cases to be assigned?

There are probably some frameworks which don't assign cases according to rules like this; I'd appreciate answers from frameworks that do, such as generative grammar. Note that my example is from English but I don't think this is an English-only phenomenon.

Answer 1

Case assignment is a big problem for formal frameworks that postulate some sort of deep agentive case-like structures like theta roles in GB because whenever the morphology clashes with the deep structure. It's not too difficult to deal with it as part of the morphology module but cases like this have to be dealt with as an exception.

On the other hand, it is not a problem in the least for functionalist or construction-based approaches. They simply look at it as a pattern fulfilling a function. Of course, your example

My mother and me went to the market.

Also has the hypercorrection counterexample:

Jane went to the market with my mother and I.

which I suspect would also be treated by many as grammatical (in non-prescriptivist contexts). In both of these cases, we're dealing with a coordinate construction where 'me' and 'I' are interchangeable as long as there is some cognitive shielding to the infelicitous interpretation. Note, that sentences

*Me went to the market.

*She went to the market with I.

are both not acceptable. This means that the idea of the case function-form pairing itself has not been lost in English. Something just happens in the coordinate constructions with 'me'. This is similar to the loss of 'whom' in English where 'Whom did your see.' is outside most native speaker intuitions whereas 'Her I saw.' is not.

English does not have a nominal case morphology so you can dismiss these examples as easy to file away surface exceptions. But you can find examples even in languages where the morphological case is unstable in even in languages where it is unavoidable. My favorite example is the Czech verb frame 'teach something to someone' which in modern Czech has both the direct and indirect object assigned the accusative case. That's because the direct agentive structure makes sense when either of the objects is on its own.

Jane teaches math (acc).

Jane teaches John (acc).

And therefore,

Jane teaches John (acc) math (acc).

However, in formal (now slightly archaic) Czech, the frame is

Jane teaches John (acc) math (dat). [Note: The frame is similar to the English 'introduce X to Y']

You can see that in this case, you can't just shove this into some surface morphological exceptions on top of a stable underlying agentive structure. There are three possible case assignments 'acc acc', 'acc dat', 'dat acc' which both map onto a plausible semantic structure but only two are acceptable in Czech morphologically.

The solution in a formal system would have to be to move this problem into the lexicon which is why it is much easier to deal with it constructionally where the division between lexicon and syntax is not as sharp and morphology is not just an afterthought.

Note: I'm not sure how this would work under Minimalism but since that is essentially a unification approach, it may not be that hard.

Answer 2

Correct me if I'm wrong, but it seems pretty straightforward:

From the Halliday's functional standpoint, both sentences are equivalent, since they deliver the same message and have exactly the same communicative implications — in this particular case, they both denote two acting subjects: my mother and I.

From the Chomsky's generativist standpoint, the major thing that matters is whether the sentence is grammatical or not. In other words, whether or not a native speaker of a certain language would tend to use this formulation in their speech.

Here we have a major caveat: There are two essentially different approaches: descriptive grammar and prescriptive grammar.

Descriptive grammar refers to the structure of a language as it is actually used by native speakers.
Prescriptive grammar refers to the structure of a language as certain people think it should be used.

There's no strict choice of Descriptive versus Prescriptive. AFAIU, in Western culture the Descriptive approach takes over. Hence, the difference:

With Descriptive grammar, it can be said that both My mother and I and My mother and me are both grammatical.

With Prescriptive grammar, someone may say that:

As to the people who tell you that you should always use "I" in conjunction with a name: they are WRONG, WRONG, WRONG! Ignore them! It's a form of "hypercorrection"--when you "correct" something that's already right based on some rule that doesn't actually apply.

Yet another example of Nominative I versus Accusative me: Professor Geoffrey Pullum:

If someone knocks at your door, and you say "Who's there?" and what you hear in response
is "It is I," don't let them in. It's no one you want to know.

Answer 3

“‘Me and her’ meets ‘he and I’: Case, person, and linear ordering in English coordinated pronouns”, by Thomas Grano (2006) seems relevant. Grano says

The puzzling distribution of case in English coordinated pronouns has sparked a number of attempted explanations.

Some explanations take case variation to be syntax-internal, and among these, some model it as resulting from optionality (Schwartz 1985, Johannessen 1998) or underspecification (Parker et al. 1988) in the syntax, and others model it as constraint reranking (Sadock 2005) or reweighting (Quinn 2005). Still, other explanations take case variation to be the result of a natural variation-free grammar pitted against explicit prescriptive instruction, through which speakers adopt either ad hoc transformational rules (Emonds 1986) or grammatical viruses (Sobin 1997) in an attempt to conform to the prescriptive standard.

(p. 23)

Maybe one of the options is not "grammatical", only "acceptable"

One solution is to say that the "naive" opinion of native English speakers is wrong, and one of the two options is ungrammatical after all.

When you ask a speaker to judge a sentence, you're really getting an acceptability judgement, not a grammaticality judgment in the technical sense of "grammaticality". And there are reasons to suspect a sentence may be judged acceptable even if it is not "grammatical" from a theoretical perspective. Norbert Hornstein has made various posts about this on the generative-grammar blog "Faculty of Language"; e.g Acceptability and Grammaticality, Degrees of grammaticality?, Judgments and grammars

This might seem like a reversion to the pre-scientific viewpoint of the prescriptivists, but there are various reasons to suppose that speakers sometimes systematically produce and accept constructions that are not "grammatical" in a generative-grammar sense. E.g. do we really expect a synchronic grammar of English to account for the remnant uses of the subjunctive in sentences like "God save the queen"?

Preminger (2017) seems to take this viewpoint about the case of coordinated noun phrases in English: he says sentences like "My mother and I went to the market" aren't actually grammatical.

(18) a. He_c1 is here on time.
b. Her_c2 and him_c2 are here on time.

➻ I’m assuming, with Sobin (1997), that the other forms are just prescriptive (hyper)correction

• that they exist doesn’t mean we should shove them in the grammar
• any more than the existence of “Numeral NP do/does not a NP make” means we should make the grammar of English verb-final

Preminger, Omer. Case in 2017: some thoughts. UMD Department of Linguistics & Maryland Language Science Center (Workshop in Honor of David Pesetsky’s 60th Birthday)

Sobin explains the acceptability of constructions like "My mother and I" as the result of a post-grammatical "virus" that changes "and me" to "and I". This is supposed to account for the over- and underextension of the rule.

This position with respect to examples like these is discussed in more detail in my and Ron Maimon's answers to When do I use “I” instead of “me?” on ELU.

Maybe there are multiple valid sources of case assignment

Maybe there is an optional process that results in an alternative case assignment. While I'm less certain about this position, I think I encountered it in a paper by Joan Maling and Rex A. Sprouse, "Strutural Case, Specifier-Head Relations, and the Case of Predicate NPs" (1995).

Maling & Sprouse provide the following example of variation in case assignment from Icelandic:

11.

a. Jón  bað   mig,  [CP að PRO vera fljótur/fljótan]                  Pred AP
   John asked me-ACC    to     be   quick-NOM/quick-ACC

b.  Jón  bað   mig,   [CP að PRO vera dyravörður/dyravörð]            Pred NP
    John asked me-ACC     to     be   doorkeeper-NOM/doorkeeper-ACC

They explain it by saying

Let us consider this to be an instance of the phenomena traditionally known as Case Attraction. Under our assumptions it is not obvious why this alternation is possible. However, let us assume that the case of the controller may optionally be copied onto PRO (as long as PRO is not assigned lexical case by the embedded predicate). Then the paradigm in (11) above and in (12)-(13) below will follow straightforwardly. In (11), PRO may either receive structural nominative from I or it may receive structural accusative via Case Attraction. In either case, I will serve as the source for case features for the predicate NP...

(p. 173)