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Learning, Recruitment,Computational Explanation [Mar. 25th, 2009|06:59 am]
Reviews, Quotes, Bibliographies from Jerry Monaco


[Below is some criticism of Jerry Fodor's retreat from the computational model of concept acquisition as he expressed it in his update of The Language of Thought in LOT 2]

Everything we know about the evolution of human intelligence indicates that, in an allied manner, our brains display a remarkable ability to cobble together ancestral reasoning schemes for, say, route planning to serve novel ends such as abstract mathematical reasoning (most mathematicians heavily employ their "geometrical intuition" to guide their thinking even in topics that bear no evident resemblance to navigational plotting). To be sure, the hasty and imperfect conclusions reached through such "borrowed reasoning" techniques often need to be scrutinized by outside checks (allied monitoring requirements are commonplace within scientific computing applications as well). Nonetheless, our most productive flights of inferential fancy remain primarily driven by various complex routines that our distant forebears had developed for the sake of efficient hunting and foraging. Indeed, the swift expansion within evolutionary time of human reasoning capacity seems explicable only through this plastic reallocation of fixed computational resources.

In this cobbling together of pre-established routines for novel applications through rerouting, we witness a basic framework for "concept learning" that, pace Fodor, does not represent a simple matter of confirming hypotheses articulated in terms of physical meanings already locked into his postulated "language of thought." Indeed, the genius of this kind of "learning" lies precisely in the fact that it allows our ancestral brain vocabulary v1, v2, . . . to shed their original semantic associations for the sake of new adaptive applications. For reasons I do not fully understand, Fodor persistently assumes that our basic "language of thought" vocabulary will maintain fixed "semantic readings" in all of their tokenings, despite the wide variety of popular computer techniques where this constancy does not obtain. True, within any specific application each brain language computational registration s can usually be semantically interpreted as carrying pertinent physical information with respect to the application at hand, but this assignment will not remain constant across all tokened appearances of s and can be sensibly attributed to s only after considering the purpose of the larger computational package to which s presently belongs. This innocent concession to the role of "embedded context" suggests that certain flavors of what Fodor dismisses as "pragmatic considerations" will prove useful to the computationalist.

In much of his recent thinking, Fodor has waxed "purist" about "conceptual grasp" in a fairly standard apriorist manner that does not benefit the CTM program at all. When a student learns a "new concept" within physics or mathematics, what does she really do? Although some official "definition" for a term like "differentiable manifold" may be found in her textbooks, many excellent pupils prefer to have some adept draw them an assortment of suggestive sketches on a napkin so that they can gain an ample sense of what Oliver Heaviside called "the practical go of the affair." In doing so, the pupil typically cobbles together an assortment of "borrowed" geometrical routines that allow her to reach appropriate heuristic conclusions about MANIFOLDS swiftly. Such students typically attend to the official "definitions" in their texts only as an "after the fact" check upon the validity of their geometrically facilitated conclusions. Indeed, some very good mathematicians pass through life without absorbing "proper definitions" for their key concepts at all. In terms of practical conceptual success, it is plainly the accumulated raft of borrowed, imperfect yet physically effective inferential and applicational techniques that keeps a concept like DIFFERENTIABLE MANIFOLD afloat within its home discipline and allows it to "lock onto" (Fodor's term) a real world correlate as "semantic value." For such definition-eschewing thinkers, Fodor cannot plausibly claim that, in any straightforward acquisitional sense, "knowing that is prior to knowing how." True, such "borrowed search routine" skills inevitably leave applicational holes that can only be closed through proper definitions and, until such steps are taken, many sentences frameable within the underlying language will lack proper truth-values. In consequence, our definition-shunning pupils will not be able to deal with such sentences adequately (these unsettled swatches of grammar often prove relatively unimportant within the discipline itself). But none of this indicates that the central core of "conceptual mastery" within real life practice doesn't rely primarily upon a rich medley of "planning" skills of exactly the sort that Fodor dismisses as "conceptually irrelevant." I can appreciate why a philosopher interested in the "metaphysics" of "concepts" or "properties" should find the resulting truth-value gaps pertinent, but they seem improperly emphasized within LOT 2's orbit of psychological concerns.


Allied considerations suggest that Fodor's firm insistence upon the "compositionality of concepts" has been prematurely decided as well. Consider a favorite example of mine: "rainbow."[3] From a parsing point of view, children learn to respond at an early age to virtually any sentential prompt with an appropriate picture: "Draw me a brown rainbow that is approaching a little girl endways." There is little doubt that she compiles the desired artistic task through recursive assembly upon the sentential components presented. But that parsing skill alone, admirable and complex as it is, does not fully prepare the child to apply such sentences to the real world with any assurance that these grammatical units will gain appropriate truth-values. Her recursive parsing for the sake of artistry relies upon a faulty picture of how the term "rainbow" obtains its real life physical significance and she must learn more about the "practical go" of adult "rainbow" talk before she will be able to apply RAINBOW to atmospheric phenomena competently. Typically, we learn such improvements simply by absorbing a revised set of skills comparable in their pragmatic content to the routines that our definition-eschewing mathematicians acquire. After this adult mastery is achieved, our further educated child will recognize that her recursive parsing of the phrase "brown rainbow" had rested upon a wrong estimation of what the trait BROWN physically signifies and how it might fit with RAINBOW, for BROWN requires a figure/background contrast that is alien to most real life RAINBOW circumstances. In this sense, the physical semantic significance of "brown rainbow" will not straightforwardly obey the brute compositionality that Fodor posits, despite the fact that limited forms of recursive capacity form an initial component within the complex group of skills an agent must display before she can be judged fully competent in RAINBOW (we probably wouldn't credit someone with a complete grasp of RAINBOW if she couldn't draw the expected false picture with a brown crayon). Careful attention to scientific concepts often reveals allied behavior.

In short, the escape routes that allow CTM to evade Fodor's anti-localist anxieties should persuade computationalists to be more sympathetic to the "conceptual" relevance of "pragmatic" factors than Fodor recommends.

To me, the most surprising aspect of LOT 2 is how apriorist its argumentation has become; scarcely a single note of what I'd call "the computational complexity of everyday routine" enters its pages. The specific methods whereby our thought reaches semantic accommodation with the world are subtle and varied and careful attention to factors that Fodor dismisses as pragmatic ephemera will likely make up a vital part of the story. In attacking "concept pragmatism" in its lofty manner, LOT 2 runs the risk of encouraging doctrinal coagulations comparable to those against which LOT 1 valiantly argued.

[1] Christoph Sigwart, Logic, Vol. I, translated by Helen Dendy (London: Swan Sonnenschein and Co., 1895), p. 248-9.

[2] Meaning, Knowledge and Reality (Cambridge: Harvard University Press, 1998), p. 412.

[3] For expansions of this example and the other considerations raised in this review, see my Wandering Significance (Oxford: Oxford University Press, 2006). The optical and psychological arrangements that sustain successful "rainbow" talk in real life are complicated and it is unclear whether unexpected natural circumstances might qualify the phrase "rainbow approaching endwise" as descriptively true.

Notre Dame Philosophical Reviews

2009-02-28 : View this Review Online : View Other NDPR Reviews

Jerry A. Fodor, LOT 2: The Language of Thought Revisited, Oxford University Press, 2008, 225pp., $37.95 (hbk), ISBN 9780199548774.

Reviewed by Mark Wilson, University of Pittsburgh