Friday, January 27, 2017

On Syntactic Structures

I am in the process of co-editing a volume on Syntactic Structures (SS) that is due out in 2017 to celebrate (aka, exploit) the 60th anniversary of the publication of this seminal work. I am part of a gang of four (the other culprits being Howard Lasnik, Pritti Patel, Charles Yang supervised/inspired by Norbert Corver). We have solicited about 15 shortish pieces on various themes. The tentative title is something like The continuing relevance of Syntactic Structures to GG. Look for it on your newsstands sometime late next year. It should arrive just in time for the 2017 holidays and is sure to be a great Xmas/ Hanukka/Kwanza gift. As preparation for this editorial escapade, I have re-read SS several times and have tried to figure out for myself what its lasting contribution is. Clearly it is an important historical piece as it sparked the Generative Enterprise. The question remains: What SS ideas have current relevance? Let me mention five.

The first and most important idea centers on the aims of linguistic theory (ch 6). SS contrasts the study of grammatical form and the particular internal (empirically to be determined) “simplicity” principles that inform it with discovery procedures that are “practical and mechanical” (56) methods that “an investigator (my emph, NH) might actually use, if he had the time, to construct a grammar of the language directly from the raw data” (52). SS argues that a commitment to discovery procedures leads to strictures on grammatical analysis (e.g. bans on level mixing) that are methodologically and empirically dubious.

The discussion in SS is reminiscent of the well-known distinction in the philo of science between the context of discovery and the context of justification. How one finds one’s theory can be idiosyncratic and serendipidous, justifying one’s “choice” is another matter entirely. SS makes the same point.[1] It proposes a methodology of research in which grammatical argumentation is more or less the standard of resaoning in the sciences more generally: data plus general considerations of simplicity are deployed to argue for the superiority of one analysis over another. SS contrasts this with the far stronger strictures Structuralists endorsed, principles which if seriously practiced would sink most any serious science. In practice then, what SS is calling for is that linguists act like regular scientists (in modern parlance, reject methodological dualism).

Let me be bit more specific. The structuralism that SS was arguing against took as a methodological dictum that the aim of analysis was to classify a corpus into a hierarchy of categories conditioned by substitution criteria. So understood, grammatical categories are classes of words, which are definable as classes of morphemes, which are defniable as classes of phonemes, which are definable as classes of phones. The higher levels are, in effect, simple generalizations over lower level entities. The thought was that higher level categories were entirely reducible to lower level distributional patterns. In this sort of analysis, there are no (and can be no) theoretical entities, in the sense of real abstract constructs that have empirical consequences but are not reducible or definable in purely observational terms. By arguing against discovery procedures and in favor of evaluation metrics SS is in effect arguing for the legitimacy of theoretical linguistics. Or, more accurately, for the legitimacy of normal scientific inquiry into language without methodological constrictions that would cripple physics were it applied.

Let me put this another way: Structuralism adopted a strong Empiricist methodology in which theory was effectively a summary of observables. SS argues for the Rationalist conception of inquiry in which theory must make contact with observables, but is not (and cannot) be reduced to them.  Given that the Rationalist stance simply reflects common scientific practice, SS is a call for linguists to start treating language scientifically and not hamstring inquiry by adopting unrealistic, indeed non-scientific, dicta. This is why SS (and GG) is reasonably seen as the start of the modern science of linguistics.

Note that the discussion here in SS differs substantially from that in chapter 1 of Aspects, though there are important points of contact.[2] SS is Rationalist as concerns the research methodology of linguists. Aspects is Rationalist as concerns the structure of human mind/brains. The former concerns research methodology. The latter concerns substantive claims about human neuro-psychology.

That said there are obvious points of contact. For example, if discovery procedures fail methodologically, then this strongly suggests that they will also fail as theories of linguistic mental structures. Syntax, for example, is not reducible to properties of sound and/or meaning despite its having observable consequences for both. In other words, the Autonomy of Syntax thesis is just a step away from the rejection of discovery procedures. It amounts to the claim that syntax constitutes a viable G level that is not reducible to the primitives and operations of any other G level.

To beat this horse good and dead: Gs contain distinct levels that interact with empirically evaluable consequences, but they are not organized so that lower levels are definable in terms of generalizations over lower level entities. Syntax is real. Phonology is real. Semantics is real. Phonetics is real. These levels have their own primitives and principles of operation. The levels interact, but are ontologically autonomous. Given the modern obsession with deep learning and its implicit endorsement of discovery procedures, this point is worth reiterating and keeping in mind. The idea that Gs are just generalizations over generalizations over generalizations that seems the working hypothesis of Deep Learners and others[3] has a wide following nowadays so it is worth recalling the SS lesson that discovery procedures both don’t work and are fundamentally anti-theoretical. It is Empiricism run statistically amok!

Let me add one more point and then move on. How should we understand the SS discussion of discovery procedures from an Aspects perspective given that they are not making the same point? Put more pointedly, don’t we want to understand how a LAD (aka, kid) goes from PLD (a corpus) to a G? Isn’t this the aim of GG research? And wouldn’t such a function be a discovery procedure?

Here’s what I think: Yes and no. What I mean is that SS makes a distinction that is important to still keep in mind. Principles of FL/UG are not themselves sufficient to explain how LADs acquire Gs. More is required. Here’s a quote from SS (56):

Our ultimate aim is to provide an objective, non-intuitive way to evaluate a grammar once presented, and to compare it with other proposed grammars (equivalently, the nature of linguistic structure) and investigating the empirical consequences of adopting a certain model for linguistic structure, rather than showing how, in principle, one might have arrived at the grammar of a language.

Put in slightly more modern terms: finding FL/UG does not by itself provide a theory of how the LAD actually acquires a G. More is needed. Among other things, we need accounts of how we find phonemes, and morphemes and many of the other units of analysis the levels require. The full theory will be very complex, with lots of interacting parts. Many mental modules will no doubt be involved. Understanding that there is a peculiarly linguistic component to this story does not imply forgetting that it is not the whole story. SS makes this very clear. However, focusing on the larger problem often leads to ignoring the fundamental linguistic aspects of the problem, what SS calls the internal conditions on adequacy, many/some of which will be linguistically proprietary.[4]

So, the most important contribution of SS is that it launched the modern science of linguistics by arguing against discovery procedures (i.e. methodological dualism). And sadly, the ground that SS should have cleared is once again infested. Hence, the continuing relevance ot the SS message.

Here are four more ideas of continuing relevance.

First, SS shows that speaker intuitions are a legitimate source of linguistic data. The discussions of G adequacy in the first several chapters are all framed in terms of what speakers know about sentences. Indeed, that Gs are models of human linguistic behavior over an unbounded domain is quite explicit (15):

…a grammar mirrors the behavior of speakers who, on the basis of a finite and accidental experience with language, can produce or understand an indefinite number of new sentences. Indeed, any explication of “grammatical in L” …can be thought of as offering an explanation for this fundamental aspect of linguistic behavior.

Most of the data presented for choosing one form of G over another involves plumbing a native speaker’s sense of what is and isn’t natural for his/her language. SS has an elaborate discussion of this in chapter 8 where the virtues of “constructional homonymity” (86) as probes of grammatical adequacy are elaborated. Natural languages are replete with sentences that have the same phonological form but differ thematically (flying planes can be dangerous) or that have different phonological forms but are thematically quite similar (John hugged Mary, Mary was hugged by John). As SS notes (83): “It is reasonable to expect grammars to provide explanations for some of these facts” and for theories of grammar to be evaluated in terms of their ability to handle them.

It is worth noting that the relevance of constructional homonymity to “debates” about structure dependence has been recently highlighted once again in a paper by Berwick, Pietroski, Yankama and Chomsky (see here and here for discussion). It appears that too many forget that linguistics facts go beyond the observation that “such and such a strong…is or is not a sentence” (85). SS warns against forgetting this, and the world would be a better place (or at least dumb critiques of GG would be less thick on the ground) if this warning 60 years ago had been heeded.

Second, SS identifies the central problem of linguistics as how to relate sound and meaning (the latter being more specifically thematic roles (though this term is not used)). This places Gs and their structure at the center of the enterprise. Indeed, this is what makes constructional homonymity such an interesting probe into the structure of Gs. There is an unbounded number of these pairings and the rules that pair them (i.e. Gs) are not “visible.” This means the central problem in linguistics is determining the structure of these abstract Gs by examining their products. Most of SS exhibits how to do this and the central arguments in favor of adding transformations to the inventory of syntactic operations involve noting how transformational grammars accommodate such data in simple and natural ways.

This brings us to the third lasting contribution of SS. It makes a particular proposal concerning the kind of G natural languages embody. The right G involves Transformations (T). Finite State Gs don’t cut it, nor can simple context free PSGs. T-grammars are required. The argument against PSGs is particularly important. It is not that they cannot generate the right structures but that they cannot do so in the right way, capturing the evident generalizations that Gs embodying Ts can do.

Isolating Ts as grammatically central operations sets the stage for the next 50 years of inquiry: specifying the kinds of Ts required and figuring out how to limit them so that they don’t wildly overgenerate.

SS also proposes the model that until very recently was at the core of every GG account. Gs contained a PSG component that generated kernel sentences (which effectively specified thematic dependencies) and a T component that created further structures from these inputs. Minimalism has partially stuck to this conception. Though it has (or some versions have) collapsed PSG kinds of rules and T rules treating both as instances of Merge, minimalist theories have largely retained the distinction between operations that build thematic structure and those that do everything else. So, even though Ts and PSG rules are formally the same, thematic information (roughly the info carried by kernel sentences in SS) is the province of E-merge applications and everything else the province of I-merge applications. The divide between thematic information and all other kinds of semantic information (aka the duality of interpretation) has thus been preserved in most modern accounts.[5]

Last, SS identifies two different linguistic problems: finding a G for a particular L and finding a theory of Gs for arbitrary L. This can also be seen as explicating the notions “grammatical in L” for a given language L vs the notion of “grammatical” tout court. This important distinction survives to the present as the difference between Gs and FL/UG. SS makes it clear (at least to me) that the study of the notion grammatical in L is interesting to the degree that it serves to illuminate the more general notion grammatical for arbitrary L (i.e. Gs are interesting to the degree that they illuminate the structure of FL/UG). As a practical matter, the best route into the more general notion proceeds (at least initially) via the study of the properties of individual Gs. However, SS warns against thinking that a proper study of the more general notion must await the development of fully adequate accounts of the more specific.

Indeed, I would go further. The idea that investigations of the more general notion (e.g. of FL/UG) are parasitic on (and secondary to) establishing solid language particular Gs is to treat the more general notion (UG) as the summary (or generalization of) of properties of individual Gs. In other words, it is to treat UG as if it were a kind of Structuralist level, reducible to the properties of individual Gs. But if one rejects this conception, as the SS discussion of levels and discovery procedures suggests we should, then prioritizing G facts and investigation over UG considerations is a bad way to go.

I suspect that the above conclusion is widely appreciated in the GG community with only those committed to a Greenbergian conception of Universals dissenting. However, the logic carries over to modern minimalist investigation as well. The animus against minimalist theorizing can, IMO, be understood as reflecting the view that such airy speculation must play second fiddle to real linguistic (i.e. G based) investigations. SS reminds us that the hard problem is the abstract one and that this is the prize we need to focus on, and that it will not just solve itself if we just do concentrate on the “lower” level issues. This would hold true of the world was fundamentally Structuralist, with higher levels of analysis just being generalizations of lower levels. But SS argues repeatedly that this is not right. It is a message that we should continue to rehearse.

Ok, that’s it for now. SS is chock full of other great bits and the collection we are editing will, I am confident, bring them out. Till then, let me urge you to (re)read SS and report back on  your favorite parts. It is excellent holiday reading, especially if read responsively accompanied by some good wine.

[1] What follows uses the very helpful and clear discussion of these matters by John Collins (here): 26-7.
[2] Indeed, the view in Aspects is clearly prefigured in SS, though is not as highlighted in SS as it is later on (see discussion p. 15).
…a grammar mirrors the behavior of speakers who, on the basis of a finite and accidental experience with language, can produce or understand an indefinite number of new sentences. Indeed, any explication of “grammatical in L” …can be thought of as offering an explanation for this fundamental aspect of linguistic behavior.
[3] Elissa Newport’s work seems to be in much the same vein in treating everything as probability distributions over lower level entities bottoming out in something like syllables or phones.
[4] Of course, the ever hopeful minimalist will hope that not very much will be such.
[5] I would be remiss if I did not point out that this is precisely the assumption that the movement theory of control rejects.


  1. A great summary of the highlights! I think the autonomy/indepenence thesis perhaps deserves a mention in its own right. I've lost count of how many times I've heard/read that Chomsky rejects semantics as a discipline. It is clear in SS, and subsequent work, that the claim is not only that syntax is not reducible to semantics, but that progress can be made on semantic issues precisely by gaining a better understanding of syntax as a constraint upon meaning. Of course, there have been many twists and turns since '57, but the basic insight that semantics can be pursued as an interface problem rather than as a problem of communication or reference seems as pertinent today as it was revolutionary back then.

    1. yep. Also beautifully brought out in that opening essay in `essays on form and interpretation'.

    2. Indeed! It's about time that book was reissued. I spent a lot of money for a battered copy:)

  2. My favorite - and the reason I think it can and should kick off almost any linguistics course at all - is that not only is there a concrete proposal about the family of Gs, but we are shown that one can PROVE things about the family of Gs - and not only that, you can develop mathematical proofs about what the possible Gs must be using nothing more than the extension of a particular G (the "string language"), and (though not shown) those proofs can be pretty airtight and (though not shown) the same results then apply to *any* further grammatical formalism, regardless of the intension of the Gs. Underappreciated and maligned by many linguists still after the distance that developed between linguistics and the formal language community (under the belief that this method presupposes a claim that matching the string language was *sufficient* for a linguistic theory - which it obviously does not). Hope this point sees a solid treatment in the book.