Sunday, August 7, 2016

Pullum on Putnam

Geoff Pullum has a recent piece in The Chronicle (here) in which he praises a deservedly famous man, Hilary Putnam. Putnam was an important 20-21st century philosopher who compiled what is arguably the best collection of essays ever in analytic philosophy. Pullum notes all of this and I cannot fault him for his judgment. However, he then takes one more step, he lauds Putnam as the “world’s most brilliant, insightful, and prescient philosopher of linguistics.” That Putnam was brilliant and insightful and (maybe) prescient is not something that I would (and did not (here)) contest. That any of this extended to his discussions of linguistics topics strikes me as either a sad commentary on the state of the philosophy of linguistics (this gets my vote) or hyperbole (it was a belated obit after all). At any rate, I want to make clear why I think that Putnam’s writings on these matters are best treated as object lessons rather than insights.  Happily, this coincides with my re-reading of Language and Mind.  Chomsky takes on some of Putnam’s more (sadly) influential criticisms of GG and (I am sure you will not be surprised to hear from me) demolishes them. The gist of Chomsky’s reply is that there is very little there there. He is right. This has not stopped analogous criticisms from repeatedly being advanced, but they have not gotten more convincing by repetition. Let me elaborate.

Putnam’s most directed critique of the Chomsky program in GG were his 1967 Synthese paper (“The ‘Innateness Hypothesis’ and Explanatory Models in Linguistics”) and a later companion piece “What is innate and why.” Chomsky considers Putnam’s arguments in detail in chapter 6 of the expanded edition of Language and Mind entitled “Linguistics and Philosophy.” Here is the play by play.

Chomsky’s critique has three parts:

1. Putnam’s specific critiques “enormously underestimate and misdescribe, the richness of structure, the particular and detailed properties of grammatical form and organization that must be accounted for by a “language acquisition model,” that are acquired by the normal speaker-hearer and that appear to be uniform among speakers and across languages” (179-180).
2. Putnam’s computational claims concerning grammatical simplicity are unfounded (181-2).
3. There is no argument for Putnam’s claim that “general multipurpose learning strategies” are sufficient to account for G acquisition and there is no current reason to think that any such exist when one looks at the grammatical details (184-5).

These are all closely related points, and Pullum is correct in suggesting that these points have repeatedly reappeared in critiques of GG. Thus, it is still true that simplistic views of what is required for G acquisition rely on underestimating and misdescribing what must be explained. It is still true that claims made on behalf of general learning strategies eschew the hard work of showing how the many “laws” linguists have discovered over the last 60 years are to be acquired without quite a bit of what looks like language specific software. Pullum is right: the critics have repeatedly picked up Putnam’s objections even after these have been shown to be inadequate and/or beside the point. Putnam has indeed been influential, and we are the worse for it.

Let me lightly elaborate on these three points.

Critics regularly avoid the hard problems. For example, look at virtually any takedown in the computer science literature of, for example, structure dependence, and you will observe this (see here and here for two recent reiterations of this complaint). All of these miss the point of the argument for structure dependence by concentrating on easily understandable illustrative toy examples intended for the general public (Reali and Christiensan) or misconstruing what the term actually denotes (Perfors et. al.).

I have said this before and I will do so again: GGers have discovered many non-trivial mid level generalizations that are the detailed fodder that fuel Poverty of Stimulus (PoS) arguments that implicate linguistically specific structure for FL. There can be no refutation of these arguments if the generalizaions are not addressed. So, Island Effects, ECP effects, Binding effects, Cross Over effects etc. constitute the “hard problems” for non-domain specific learning architectures. If you think that a general learner is the right way to go you need to account for these sorts of data. And there is, by now, a lot of this (see here for a partial list). However, advocates of “simpler” less domain specific accounts (almost) never broach these details, though absent this the counter proposals are at best insufficient and at worst idle.

It seems that Putnam is the first in a continuing line of critics that have decided that one can ignore the linguistic details when arguing against undesired cognitive conclusions. As Chomsky notes contra Putnam, there is more to phonology than a “short list of phonemes” from which languages can choose (e.g. there is also cyclic rule application) and there is more to syntax than proper names (e.g. there are also Island effects). Putnam failed to engage with the details (as discussed in Chomsky’s work at the time) and in doing so established a tradition that many have followed. It is not, however, a tradition that anyone should be proud to be part of, whatever its pedigree.

Putnam advanced another argument that is sadly still alive today. He argued that invoking innateness doesn’t solve the acquisition problem, but only “postpones” it. What’s this mean? The argument seems to be that stuffing FL with innate structure is explanatorily sterile as it simply pushes the problem back one step: how did the innate structure get there?[1] Frankly, I find this claim philosophically embarrassing. Why?

One of the main professional requirements of a card-carrying philosopher is that her/his work clarify what point an argument is aiming to make; what question is it trying to answer? Assuming an FL that is structured with domain specific linguistic structure addresses the question of how an LAD can acquire its language specific G despite the poverty of the relevant PLD (here’s Chomsky 184-5: “Invoking an innate representation of universal grammar does solve the problem of learning (at least partially), in this case.”) If such a UG structured FL suffices to solve the PoS problem it raises a second question: how did the relevant (domain specific) mental structure get there (i.e. why is FL structured with language proprietary UGish principles). Note, these are two different questions (viz. “what FL is required to project a GL from PLDL?” is different from “how did the FL we in fact have get embedded in our mental architecture in the first place?”). Consequently failing to answer the evolutionary questions concerning the etiology of rich innate mental structure does not imply a failure to answer/address the question of how an individual LAD acquires its GL.

Of course, it is not an irrelevant either, or might not be. If we could show that a given domain specific FL could not possibly have evolved then we are pretty sure that the postulated innate mental mechanism in the individual cannot be a causal factor in G acquisition. After all, if such an FL cannot be there then it isn’t there and if it isn’t there then it cannot help with the acquisition problem. But, and this is very important, nobody has even the inklings of an argument against the assumption that even a very rich domain specific FL could not have arisen in humans. Right now, this impossibility claim is at best a hunch (viz. an ungrounded prejudice). Why? Because we currently have very few ideas about how any cognitive structures evolve (as Lewontin has famously noted). Indeed, even the evolution of seemingly simple non-cognitive structures remains mysterious (see here for a recent example). So, any confident claims that even a richly domain specific FL is evolutionarily impossible is not on the cards right now and is thus a weak counter-argument against an FL that can solve the acquisition problem.[2]

A sidebar: now of this is meant to imply that this evolutionary question is uninteresting. I am an unrepentant Minimalist and take seriously the minimalist problematic: how could an FL such as ours arisen in the species. As such I am all in favor of purging FL of as much UG as possible and trading this for general cognitive mechanisms. However, because I consider this an interesting problem I resist fiat solutions; you know, bold yet vacuous declarations that a general learner can do it all without any detailed indications dealing with specific claims resting on bland assurances that it is in principle possible. I like the question so much that I want to see details; actual explanations engaging with specific proposed UG structures. I love reduction, I just don’t like the cheap variety. So derive your favorite UG based accounts from more general principles and watch me snap to attention.

BTW, Chomsky makes just this point as early as 1972. Here is a quote from his discussion of Putnam (182):

I would, naturally, assume that there is some more general basis in human mental structure for the fact (if it is a fact) that languages have transformational grammars; one of the primary scientific reasons for studying language is that this study may provide some insight into general properties of mind. Given those specific properties, we may then be able to show that transformational grammars are “natural.” This would constitute real progress, since it would enable us to raise the problem of innate conditions on acquisition of knowledge and belief in a more general framework. But it must be emphasized that, contrary to what Putnam asserts, there is no basis for assuming that “reasonable computing systems” will naturally be organized in the specific manner suggested by transformational grammar.

One might argue that Chomsky’s version of minimalism is his way of making good on Putnam’s computational conjecture, though I doubt that Putnam would see it that way. At any rate, Minimalism starts from the recognition that domain specific FLs can solve standard linguistic acquisition problems (i.e. PoS problems) and then tries to reduce the linguistic specificity of the various principles. It does not solve the domain specificity problem by ignoring the relevant domain specific principles.

One more point and I end. In his reply to Putnam Chomsky outlines a very reasonable strategy for eliminating domain specificity in favor of something like general learning.[3] In his words 184):

A non dogmatic approach to this problem [i.e. the acquisition of language NH] can be pursued, though the investigation of specific areas of human competence, such as language, followed by the attempt to devise a hypothesis that will account for the development of such competence. If we discover that the same “learning strategies” are involved in a variety of cases, and that these suffice to account for the acquired competence, then we will have good reason to believe Putnam’s empirical hypothesis is correct. If, on the other hand, we discover that different innate systems…have to be postulated, then we will have good reason to believe that an adequate theory of mind will incorporate separate “faculties,’ each with unique or partially unique properties.

See here for another discussion elaborating these themes.

To sum up: The problem with Putnam’s philosophical discussions of linguistics is that they entirely missed the mark. They were based on very little detailed knowledge of the GG of the time. They confused several questions that needed to be kept separate and they philosophically begged questions that were (and still are) effectively empirical. The legacy has been a trail of really bad arguments that seem to arise zombie like despite their inadequacy. Putnam wrote many interesting papers. Unfortunately his papers on linguistics are not among these. Let these rest in peace.[4]

[1] There are actually two points being run together here. The first is that any innate structure whether it is domain specific or not begs the explanatory question. The second is that only a domain specific “rich” FL does so. The form of the argument Putnam presents applies to either for both call for an evolutionary account of how the mental capacities arose. Humans might after all have a richer general cognitive apparatus than our ape cousins and how it arose would demand explanation ever if it were not domain specific. However, the thinking usually is that only domain specific richness is problematic. In what follows I abstract from this ambiguity.
[2] Gallsitel has noted that cognitive domain specificity is biologically quite reasonable (see here for discussion and links).
[3] See here for another discussion along the same lines channeling Reflections on Language
[4] Perhaps it is not surprise that Dan Everett loved this Pullum post. In his words: “Glad you noticed this! He was indeed one of the best of the last 100 years.” This comment does not indicate what Everett found so wonderful, but given the topic of the Pullum’s post and Everett’s own added confusions to the philosophical issues, it is reasonable to assume that he found the Putnam critiques against domain specific nativism compelling. But you knew he would, right?

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