Two thought experiments reviewed: comments on J. A. Fodor's paper: ``Cognitive science and the twin-Earth problem''.

Abstract

The issues raised by the anti-individualist arguments in Hilary Putnam's "The meaning of 'meaning'" and my "Individualism and the mental" are various and complicated.I shall be able to touch on only a few of these issues in this space.What makes matters more complicated is that Putnam's interests and viewpoint differ from mine.Although a comparison of our views would be useful, I will have to concentrate entirely on those of Fodor's remarks that concern my work.I begin by setting out two thought experiments, which I formulate in ways that raise a minimum of issues that are extraneous to my primary interests.Then I will state what I take the thought experiments to show.Finally, I will discuss Fodor's criticisms. 1 The first thought experiment is a variant on Putnam's original Twin Earth case.For our purposes, the differences are significant.Assume that Al has a variety of beliefs and occurrent thoughts involving the notion of aluminum.He thinks that aluminum is a light, flexible metal, that many sailboat masts are made out of aluminum, that someone across the street recently bought an aluminum canoe.These occurrent and state-like attitudes are correctly (truly) described with that-clauses containing 'aluminum' in oblique, not purely transparent position.That is, exchanges of expressions that are coextensive with 'aluminum' (apply to exactly the same quantities of aluminum) do not in general preserve the truth-value of these original attitude ascriptions.Now, as a second step in the thought experiment, conceive of a physical duplicate of Al who lives on a fraternal twin of Earth.Call him Al z .Al/ is bodily identical with Al.He undergoes the same stimulations on his bodily surfaces, excepting minor micro-and gravitational differences, engages in the same motions, utters the same sounds, has the same experiences-insofar as these stimulations, motions, and experiences are nonintentionally described.This physical and phenominal similarity-virtual type-identity-is preserved from birth to the present.I will suppose also that there are internal-causal, functional, and syntactical similarities as long as they are specified nonintentionally