Those of you who don't work on case probably have in your heads some rough sketch of how case works. (e.g. Agree in person/number/gender between a designated head and a noun phrase, resulting in that noun phrase being case-marked.) What you need to realize is that basically nobody who actually works on case believes that this is how case works.Now, whether or not this is really how it all went down, possibly-apocryphal-Mark has a point. In fact, I'm here to tell you that his point holds not only of case, but of agreement, too.
In one sense, this situation is probably not all that unique to case & agreement. I'm sure presuppositions and focus alternatives don't actually work the way that I (whose education on these matters stopped at the introductory stage) think they work, either. The thing is, no less than the entire feature calculus of minimalist syntax is built on this purported model of case & agreement. [If you don't believe me, go read "The Minimalist Program" again; you'll find that things like the interpretable-uninterpretable distinction are founded on the (supposed) behavior of person/number/gender and case (277ff.).] And it is a model of case & agreement that – to repeat – simply doesn't work.
So what model am I talking about? I'm really talking about a pair of intertwined theories of case and of agreement, which work roughly as follows:
- there is a Case Filter, and it is implemented through feature-checking: each noun phrase is born with a case feature that, were it to reach the interfaces (PF/LF) unchecked, would cause ungrammaticality (a.k.a., a "crash"); this feature is checked when the noun phrase enters into an agreement relation with an appropriate functional head (T0, v0, etc.), and only if this agreement relation involves the full set of nominal phi features (person, number, gender)
- agreement is also based on feature-checking: the aforementioned functional heads (T0, v0, etc.) carry "uninterpretable person/number/gender features"; if these reach the interfaces (PF/LF) unchecked, the result is – you guessed it – ungrammaticality (a.k.a., a "crash"); these uninterpretable features get checked when they are overwritten with the valued person/number/gender features found on the noun phrase
From the vantage point of 2016, however, I think it is quite safe to say that none of this is right. And, in fact, even the Abstractness Gambit (the idea that (1) and (2) are operative in the syntax, but morphology obscures their effects) cannot save this theory.
What follows builds heavily on some of my own work (though far from exclusively so; some of the giants whose shoulders I am standing on include Marantz, Rezac, Bobaljik, and definitely-not-apocryphal Mark Baker) – and so I apologize in advance if some of this comes across as self-promoting.
Let's start with (1). Absolutive(=ABS) is a structural case, but there are ABS noun phrases that could not possibly have been agreed with, living happily in grammatical Basque sentences. How do we know they could not possibly have been agreed with (not even "abstractly")? Because we know that (non-clitic-doubled) dative arguments in Basque block agreement with a lower ABS noun phrase, and we can look specifically at ABS arguments that have a dative coargument. (Indeed, when the dative coargument is removed or clitic-doubled, morphologically overt agreement with the ABS – impossible in the presence of the dative coargument – becomes possible.)
So if an ABS noun phrase in Basque has a dative coargument, we know that this ABS noun phrase could not have been targeted for agreement by a head like v0 or T0 (because they are higher than the dative coargument). Notice that this rules out agreement with these heads regardless of whether that supposed agreement is overt or not; it is a matter of structural height, coupled with minimality. The distribution of overt agreement here serves only to confirm what our structural analysis already leads us to expect.
And yet despite the fact that it could not have been targeted for agreement, there is our ABS noun phrase, living its life, Case Filter be damned. [For the curious, note that this is crucially different from seemingly similar Icelandic facts, which Bobaljik (2008) suggests might be handled in terms of restructuring. That is because whether the embedded predicate is ditransitive (=has a dative argument) or monotransitive (=lacks one) cannot, to the best of my knowledge, affect the restructuring possibilities of the embedding predicate one bit.]
If you would like to read more about this, see my 2011 paper in NLLT, in particular pp. 929 onward. (That paper builds on the analysis of the relevant Basque constructions that was in my 2009 LI paper, so if you have questions about the analysis itself, that's the place to look.)
Moving to (2), this is demonstrably false, as well. This can be shown using data from the K'ichean languages (a branch of Mayan). These languages have a construction in which the verb agrees either with the subject or with the object, depending on which of the two bears marked features. So, for example, Subj:3sg+Obj:3pl will yield the same agreement marking (3pl) as Subj:3pl+Obj:3sg will. It is relatively straightforward to show that this is not an instance of Multiple Agree (i.e., the verb does not "agree with both arguments"), but rather an instance of the agreeing head looking only for marked features, and skipping constituents that don't bear the features it is looking for. Just like an interrogative C0 will skip a non-[wh] subject to target a [wh] object, so will the verb in this construction skip a [sg] (i.e., non-[pl]) subject to target a [pl] object.
This teaches us that 3sg noun phrases are not viable targets for the relevant head in K'ichean. Ah, but now you might ask: "What if both the subject and the object are 3sg?" The facts are that such a configuration is (unsurprisingly) fine, and an agreement form which is glossed as "3sg" shows up in this case (so to speak; it is actually phonologically null). That's all well and good; but what happened to the unchecked uninterpretable person/number/gender features on the head? Remember, they couldn't have been checked, because everything is now 3sg. And if 3sg things were viable targets for this head, then you could get "3sg" agreement in a Subj:3sg+Obj:3pl configuration, too – by simply targeting the subject – but in actuality, you can't. [This line of reasoning is resistant even to the "but what about null expletives?" gambit: if the uninterpretable phi features on the head were checked by a null expletive, then either the expletive is formally plural or formally singular. If it is singular, then we already know it could not have been a viable target for this head; if it is plural, and it has been targeted for agreement, then we predict plural agreement morphology, contrary to fact. Thus, alternatives based on a null expletive do not work here.]
What about Last Resort? It is entirely possible that grammar has an operation that swoops in should any "uninterpretable features" have made it to the interface unchecked, and deletes the offending features. But now ask yourself this: what prevents this operation from swooping in and deleting the features on the head even when there was a viable agreement target there for the taking (e.g. a 3pl nominal)? i.e., why can't you just gratuitously fail to agree with an available target, and just have the Last Resort operation take care of your unchecked features later? The only possible answer is that the grammar "knows that this would be cheating"; the grammar makes sure the Last Resort is just that – a last resort – it keeps track of whether you could have agreed with a nominal, and only if you couldn't have are you then eligible for the deletion of offending features. Put another way, the compulsion to agree with an available target is not reducible to just the state of the relevant features once they reach the interfaces; it is obligatory independently of such considerations. You see where this is going: if this bookkeeping / independent obligatoriness is going on anyway, uninterpretable features become 100% redundant. They bear exactly none of the empirical burden (i.e., there is no single derivation in the entire grammar that would be ruled out by unchecked features, only by illicit application of the Last Resort operation).
Bottom line: there is no grammatical device of any efficacy that corresponds to this notion of "uninterpretable person/number/gender feature."
At this juncture, you might wonder what, exactly, I'm proposing in lieu of (1-2). The really, really short version is this: agreement and case are transformations, in the sense that they are obligatory when their structural description is met, and irrelevant otherwise. (Retro, ain't it?) To see what I mean, and how this solves the problems associated with (1) and (2), I'm afraid you'll have to read some of my published work. In particular, chapters 5, 8, and 9 of my 2014 book. Again, sorry for the self-promotional nature of this.
Every practicing linguist has, in their head, a "toy theory" of various phenomena that are not that linguist's primary focus. This is natural and probably necessary, because no one can be an expert in everything. The difference, when it comes to case and especially when it comes to agreement, is that these phenomena have been (implicitly or explicitly, rightly or wrongly) taken as the exemplar of feature interaction in grammar. And so other members of the field have (implicitly or explicitly) taken this toy theory of case & agreement as a model of how their own feature systems should work.
And lest you think I have constructed a straw-man, let me end with an example. If you follow my own work, you know that I have been involved in a debate or two recently where my position has amounted to "such and such phenomenon X is not reducible to the same mechanism that underlies agreement in person/number/gender." What strikes me about these debates is the following: if A is the mechanism that underlies agreement, these (attempted) reductions are not reductions-to-A at all; they are reductions-to-the-LING-101-version-of-A (e.g. Chomsky's Agree), which – to paraphrase possibly-apocryphal-Mark – nobody who works on agreement thinks (or, at least, nobody who works on agreement should think) is a viable theory of agreement.
Now, it is logically possible that a feature calculus that was invented to capture agreement in person/number/gender (e.g. Agree), and turns out to be ill-suited for that purpose, is nevertheless – by sheer coincidence – the right theory for some other phenomenon (or set of phenomena) X. But even if that turns out to be the case, because the mechanism in question doesn't account for agreement in the first place, there is no "reduction" here at all.