Fodor's Causal Argument and Unwarranted Supervenience Assumption; Examining Egan's Argument

In this essay, I examine Fodor's argument in favor of psychological individualism and Egan's response. According to Fodor's causal argument, every scientific theory individualizes states or identities according to their causal powers. Therefore, Common sense intentional psychology should individualize the states according to the narrow content. Fodor offers two counter-examples to the above argument. According to the second counter-example (2), the anti-individualist claims that since the behavior of twins is distinct in type, their mental states must also be distinct in type, and according to the causal powers of the distinct mental states of type, they are not identical. Fodor gives two responses to the second counter-example. According to (2a), Fodor wants to prove that we should not consider the behavior of twins as different. As a result, the mental states of twins are not distinct. In response to (2a), Egan claims that Fodor's argument is based on the assumption that behavioral types supervene on brain types. According to (2b), Fodor makes two similar arguments by likening "anti-individualist psychology" to "H and T particle theory." One is to distinguish a type of Oscar's mental state from his twin; The second is to distinguish between H-particles and T-particles. In response to (2b), Egan claims that Fodor presupposes an unwarranted supervenience assumption in both arguments without providing an argument for it. Finally, I conclude that if Fodor has no good argument for the doctrine of the supervenience, then he has no reason to distinguish between extensive contents and other relative properties.