Sunday, September 03, 2006

Herring's Review of Chomsky

I've just finished my third read this weekend of Chomsky's Review of Skinner in preparation for a presentation on it tomorrow. I have to say I'm a bit surprised to find that I agree with it less than I expected to.

It's true that I'm no great fan of Chomsky. I'm especially allergic to his political writings - but some of the bad habits exhibited in them extend to his Linguistic work as well. These include failure to mention relevant but inconvenient facts, use of inappropriate and overly facile examples, indulgence in several common logical fallacies - most notably false dichotomy and circular reasoning. In addition, his writing style can be difficult, obscuring his point and leaving me with the impression, upon finishing, that I've put in a lot of effort to small reward.

It would, however, be foolish to deny that Chomsky has had a significant - and mostly positive - impact on the field of Linguistics. His work in formal languages is invaluable, and the basic terms in which we discuss human language today have remained largely intact from some of his early writings. Most importantly, it is the name of Chomsky that has come to be associated more than any other with the rejection of Behaviorism and the launching of the Cognitive Revolution - a step without which the study of human language, put simply, would not be possible in any useful sense.

It is because I am so opposed to Behaviorism that I expected, for once, to fully agree with something that Chomsky wrote. However, the more times I read through "A Review of B. F. Skinner's Verbal Behavior," the less inclined I am to give the Devil his due.

Perhaps it would be best to start off with what I did like.

In one particularly insightful passage, Chomsky writes:

The questions to which Skinner has addressed his speculations are hopelessly premature. It is futile to inquire into the causation of verbal behavior until much more is known about the specific character of this behavior; and there is little point in speculating about the process of acquisition without much better understanding of what is acquired.

This is, in my opinion, the most important sentence of the essay, an excellent point, and an observation that applies not only to Skinner's work in the 1950s but also equally well to a host of researchers here at IU today.

Noah and I have discussed this point in some detail when talking about the nativist debate, in fact. There is a heated and ongoing debate in Linguistics about whether (and if so, to what extent) any account of language acquisition and linguistic competence must resort to the postulation of genetically determined language-specific cognitive mechanisms. In other words, how much of language is innate?

Noah and I generally agree that at least some of language must be innate, that it probably isn't innate to the extent Chomsky seems to think it is, but that in any case this question belongs on the backburner pending further evidence. There simply isn't enough yet known about language to say with any certainty how much and which parts of it have to be explained with reference to genetically-determined mechanisms. The best any of us can do at this point is make intuitive guesses, nothing more.

And that seems to me to be more or less what Chomsky is saying with regard to the question of how external stimuli relate to verbal responses. It is, of course, the goal of language science to provide a mechanistic account of human language use - but we're a long way from being able to do that. Certainly any facile recording of pairs of stimuli and their associated verbal responses at this point is likely to be uninformative at best, profoundly misleading at worst.

As Chomsky writes elsewhere:

It is clear that what is necessary in such a case is research, not dogmatic and perfectly arbitrary claims, based on analogies to that small part of the experimental literature in which one happens to be interested.

Which brings me to Chomsky's other good point:

One would naturally expect that prediction of the behavior of a complex organism (or machine) would require, in addition to information about external stimulation, knowledge of the internal structure of the organism, the ways in which it processes input information and organizes its own behavior.

Indeed. And this is the point, really. What is an adequate explanation for the behvior of rats need not translate to humans - or even monkeys and dogs. It is indeed absurd, when confronted with a complicated machine like a human, to write the internal structure entirely out of the equation, as though the complexity of the organism were incidental.

Outside of these two excellent points, I also agree with Chomsky's general approach to the problem - which is to show that Skinner's use of terminology is imprecise, and that his choice of terms in general serves more to add a veneer of scientific objectivity to the subject than it does to actually explain anything.

We must decide, first of all, whether any physical event to which the organism is capable of reacting is to be called a stimulus on a given occasion, or only one to which the organism in fact reacts; and correspondingly, we must decide whether any part of behavior is to be called a response, or only one connected with stimuli in lawful ways. Questions of this sort pose something of a dilemma for the experimental psychologist. If he accepts the broad definitions, characterizing any physical event impinging on the organism as a stimulus and any part of the organism's behavior as a response, he must conclude that behavior has not been demonstrated to be lawful. In the present state of our knowledge, we must attribute an overwhelming influence on actual behavior to ill-defined factors of attention, set, volition, and caprice. If we accept the narrower definitions, then behavior is lawful by definition (if it consists of responses); but this fact is of limited significance, since most of what the animal does will simply not be considered behavior. Hence, the psychologist either must admit that behavior is not lawful (or that he cannot at present show that it is -- not at all a damaging admission for a developing science), or must restrict his attention to those highly limited areas in which it is lawful (e.g., with adequate controls, bar-pressing in rats; lawfulness of the observed behavior provides, for Skinner, an implicit definition of a good experiment).

Skinner does not consistently adopt either course. He utilizes the experimental results as evidence for the scientific character of his system of behavior, and analogic guesses (formulated in terms of a metaphoric extension of the technical vocabulary of the laboratory) as evidence for its scope. This creates the illusion of a rigorous scientific theory with a very broad scope, although in fact the terms used in the description of real-life and of laboratory behavior may be mere homonyms, with at most a vague similarity of meaning. To substantiate this evaluation, a critical account of his book must show that with a literal reading (where the terms of the descriptive system have something like the technical meanings given in Skinner's definitions) the book covers almost no aspect of linguistic behavior, and that with a metaphoric reading, it is no more scientific than the traditional approaches to this subject matter, and rarely as clear and careful.

This is insightful - and again, I think it applies to many researchers even in the present day, not just Skinner himself.

But it is also here where Chomsky and I largely part ways.

Chomsky is correct to identify the problems he does with Skinner's program. There is indeed an important difference between studying the behavior of a caged rat under laboratory conditions and studying free humans in the field. While in the case of the rat we can say with great certainty which stimulus elicited which response, doing so in the case of the human is much more problematic. Chomsky's assertion that any meaningful use of the terms stimulus and response will necessarily need to make reference to internal mental states can hardly be denied. Without refernce to at least some subject-internal mechanisms, it will be impossible to pair stimuli with responses in any lawful way. This can easily be seen if we consider the full range of responses that a person might give to the presence of, say, a chair. They are, quite literally, limitless. We can only know what "stimulus" (what aspect of the chair, in this case) is "controlling" the response after we have already heard the response. And then all the response really tells us is something about what was going on in the subject's mind. There is no external reason we are aware of to suppose that the subject is "under the control" of the material out of which the chair is made (as opposed to, say, how comfortable it is or whether it looks nice against the other furniture) - at least no objective external reason. Resorting to the device of saying that any number of aspects (or combination of aspects) of a present stimulus could be "controlling" the response is indeed to drive the stimulus "back into the organism." A proper study of human verbal behavior will not be possible, it seems, without references to internal states and mechanisms.

What needs to be stressed at this point, however, is that these internal states and mechanisms are only presently obscure. Presumably, everything that goes on in the mind is itself mechanistic and predictable, given exhaustive knowledge of the internal structure of the organism. (This must, at least, be taken as an assumption in the field of Cognitive Science. It is an assumption that may turn out to be erroneous, but if so Cognitive Science will have been revealed as a blind alley.) The chain of causation between stimulus and response is therefore not broken in reality - only in what we are presently able to observe.

It is an interesting question as to whether it will ever be possible to completely observe a human mind in action. There is certainly no reason to suspect that the technology to do so will never be available. However, there is a question of whether the magnitude of the internal operations involved will admit of any kind of grasp in a human consciousness. It may be that humans are limited in the amount of detail to which they can pay attention in such a way that complete grasp of a human mind by another human mind will never be possible.

Of course, this is not to suggest that any single person need represent to himself every neuron of the mind under scruitiny. What it suggests is that the patterns of neuronal activity may themselves not admit of easy classification into computational functions that human brains can grasp. Of course, we hope that they will - but it remains to be seen.

In any case, it seems that Chomsky's rejection of Skinner's paradigm is really only a rejection of the extreme to which Skinner has taken it, not a rejection of pairings of stimuli and responses as an appropriate model for the explanation of human behavior. As such, as an argument against Behaviorism, this rings incomplete. In particular, choosing the most extreme of all the Behaviorists as their representative seems a weak approach. It has the flavor of a straw man argument.

That Skinner's use of terms is imprecise proves only that Skinner has failed to define his program well. Other researchers may do better. It is these researchers that one needs to address if he wishes to argue against Behaviorism in general.

Further, and perhaps more to the point, demonstrating that Skinner's program is a mess doesn't bring us any closer to answering the question of to what extent internal mechanisms are needed to account for verbal behavior and how we should go about studying them. Clearly, facile pairings of stimuli and responses with no refernece to internal structure will be inadequate. But that only eliminates one extreme of a whole spectrum of possible approaches. To simply say that we need to study internal structure isn't very helpful without some guide as to what constitutes "objectivity" in such a study and what the potential pitfalls are. Absent some elaboration here, Chomsky is really no better than Skinner, relying on purely conceptual arguments to defend a program which may have no real applicability.

Ah, but what program is Chomsky defending as an alternative? He doesn't say - aside from noting that

If the contribution of the organism is complex, the only hope of predicting behavior even in a gross way will be through a very indirect program of research that begins by studying the detailed character of the behavior itself and the particular capacities of the organism involved.

So there is a real sense in which this review is unfair, or at least unhelpful. In Chomsky's later works we do get a look at what he has in mind as an alternative, and it very definitely suffers from methodological and conceptual problems of its own.

In summary, this review is useful for rejecting a particular extreme of Behaviorism. Beyond that, it suggests (plausibly, for the most part) that the proper approach to the study of human verbal behavior will have to rely on a great deal of indirect inferences about the internal structure of the organism. Skinner's approach is definitely out, as are probably most similar approaches. However, no concrete suggestion for an alternative has been given, nor is there any serious discussion of the problems of the "indirect methods" that led to the rise of Behaviorism in the first place. I am convinced, in other words, that Skinner is probably not worth reading. I am not convinced, however, that Chomsky can really help me find alternatives.


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