Ken Aizawa

Despite the prominence of the systematicity argument in the debate between Classicists and Connectionists, there is extremely widespread misunderstanding of the nature of the argument. For example, Matthews (1994), has argued that the systematicity argument is a kind of trick, where Niklasson and van Gelder (1994), have claimed that it is obscure. More surprisingly, once one examines the argument carefully, one finds that Fodor, Pylyshyn, and McLaughlin, themselves have not fully understood it. 1 In part as a result of this, many Connectionists who have tried to meet the challenge of explaining the systematicity of thought have been misled about what this challenge involves (e.g. Pollack 1990; Smolensky 1990; Niklasson and van Gelder 1994). I have five principal objectives in this paper. First, I want to respond to those who believe that the systematicity argument is mere obscurity by providing a clear presentation of it. Second, and at the same time, I want to respond to those who believe the argument is mere trickery by showing it to be an instance of a rather familiar form of legitimate scientific reasoning. Third, having seen what sort of reasoning is involved in the argument, I wish to indicate how certain attempts to meet the challenge of systematicity are inadequate. Fourth, having seen the explanatory standard set by the systematicity argument, I want to indicate how even Fodor, Pylyshyn, and McLaughlin, fail to see how Classicism fails to meet the standard. Fifth, and finally, I wish to indicate what consequences the foregoing considerations have for the prospects of Classicism and Connectionism.

This paper has two principal goals. The first is to set out a bit of conceptual cartography, mapping out a number of distinct conceptual issues that are frequently conflated in the vast literature on multiple realization. The second is to review very briefly how work by Carl Gillett and myself attempts to address a few of the many problems of multiple realization. One of these is explaining what Jerry Fodor apparently took to be mysterious, namely, how multiple realization of properties is possible.

Abstract:Polger and Shapiro have two principal takes on realization: An individual being a member of a kind is an instance of realization, and a kind being a member of a kind is an instance of realization. Both of these conceptions of realization suffer from serious objections. The broader conclusion that emerges from these many flaws is that, while their versions of realization and multiple realization are implausible, this does nothing to undermine the viability of more recent versions of nonreductive physicalism based on property instances.

In an earlier paper, we argued that Fodorian Semantics has serious difficulties. However, we suggested possible ways that one might attempt to fix this. Ted Warfield suggests that our arguments can be deflected and he does this by making the very moves that we suggested. In our current paper, we respond to Warfield's attempts to revise and defend Fodorian Semantics against our arguments that such a semantic theory is both too strong and too weak. To get around our objections, Warfield proposes a modified reading of one of Fodor's conditions and proposes adding a new condition to the theory. We show that neither the modified reading nor the additional condition saves the asymmetric causal dependency approach to naturalized semantics.

Explanations of psychological regularities in terms of biological regularities are undoubtedly appealing for many reasons. In addition, the scientific methodology that searches for such explanations certainly has merit. Nonetheless, the history of neuroscience, psychology, and computer science over the last one hundred years, indicates that such explanations are difficult to find and that the methodology of searching for them often frustrating. Recent attempts to provide "neurally-inspired" explanations of psychological regularities embodied in the theory of parallel distributed processing, PDP, also show signs of these difficulties. The more neurobiologically accurate portions of PDP are isolated from the more psychologically plausible portions, while the portions dedicated to computational analyses of neural networks tend to be isolated from both biology and psychology. Since, however, we may be sure that some day there will be some true scientific and philosophic theory of the role of neurons in mentation, we may press on in the enterprise, using what we have now as a point of departure. In this spirit, we may consider evolutionary explanations of features of our neural hardware. By pursuing evolutionary explanations via computer simulations, genetic algorithms, we have a new direction in which to proceed in our neural network theorizing. A second project we pursue is the application of a neural network studied in PDP computer science, the Boltzmann machine, to psychological phenomena. Here the psychological phenomena are those found in human decision making under risk and captured in Kahneman and Tversky's prospect theory