Hoffman (1998) tells us of a number of difficulties connectionists may face in any attempt to model neural activity with connectionist networks. I have no reason to doubt that, but it is more of a problem for connectionists than it is for my argument (Green 1998).
2. Of course, there are many possible avenues of apparent escape, and only further empirical research will show which, if any, of these are authentic. The most obvious is the frequent claim that the network units do not represent individual neurons, per se, but larger groupings of neurons (bundles, clusters, assemblies, or what have you). It is entirely up to connectionists whether they try to make the "neural" part of the phrase "neural net" stick or, by contrast, attempt to articulate a new domain that exists, somehow, "midway" between the immediate constituents of propositional attitudes, on the one hand, and individual neurons, on the other.
3. Although he does not say so directly, Hoffman seems to believe that his argument has some bearing on mine (Green 1998). I believe this arises from a slight misreading of my target article common to a number of neuroscientists who have read it. I had nothing whatever to say about how SUCCESSFUL connectionists might hope to be, ultimately, in the attempt to use connectionist networks as literal models of neural activity. My point was, rather, that if they do not make such an attempt, their "models" are left with very little in the way of a cognitively relevant domain to map. If Hoffman is right that there are cognitively relevant aspects of neural activity that connectionist networks are unlikely ever to be able to capture, then the problem before them is even more dire than I had suspected.
4. One final thought. Hoffman makes mention of dynamical systems, which are becoming increasingly popular in cognitive science these days. He specifically states that the dynamics he is talking about occur within and between neurons; that is to say, he has a clear domain. Many other cognitive dynamicists, however, are not so clear, and may well fall into the very same difficulty that I outlined for connectionists in my target article.
Green, C. D. (1998) Are connectionist models theories of cognition? PSYCOLOQUY 9(4) ftp://ftp.princeton.edu/pub/harnad/Psycoloquy/1998.volume.9/ psyc.98.9.04.connectionist-explanation.1.green
Hoffman, W. C. (1998) Are neural nets a valid model of cognition: Commentary on Green on connectionist-explanation. PSYCOLOQUY 9(12) psyc.98.9.12.connectionist-explanation.9.hoffman ftp://ftp.princeton.edu/pub/harnad/Psycoloquy/1998.volume.9/
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