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[ Pobierz całość w formacie PDF ] argument given applies only to a restricted range of concepts, not to all concepts. It is hard to see how it might be extended to concepts of mathematics, ethics, aesthetics, colours, sensations, logic and so on. The reason is that it is not clear how we can keep the believer's internal properties constant while varying the environment in the appropriate way, as we could with the water and Putnam cases. Nevertheless, we can apply a related -75- externalist thesis more broadly: we can hold that whenever a concept is possessed its identity is determined by the property the belief is about, where the property is itself a nonmental entity of some sort. When I am said to believe that the room is square, the concept square is attributed to me by referring to the property of being square, since this is what the word 'square' refers to--and that property is not something mind-dependent, or else nothing could be square without a mind to apprehend it. So, quite generally, whenever a content is attributed to someone this is achieved by referring to something nonmental in nature (unless of course the property is itself a mental property, as with pain). Externalism of this sort is thus pervasively true, since most content represents nonmental states of affairs. So, yes, beliefs are not generally in the head. The consequences of this thesis which we shall consider concern: psychological explanation, self-knowledge, scepticism, and consciousness. As to psychological explanation, a problem arises because of a prima facie incompatibility between externalism and the explanatory power of psychological ascriptions. We generally take it that a person's actions can be explained by assigning beliefs and desires to the person, and beliefs and desires essentially have content: she went to the shops because she desired a drink of water and she believed that the shops sold water. The action is explained by saying what she desired and believed. But now notice that on twin earth this thirsty person's counterpart is also going to the shops and buying something cool and clear to drink--retaw. The two bodies are behaving in exactly the same ways, even though they desire and believe different things. This means that the mental difference between them has no explanatory relevance to how their bodies behave; what explains their identical behaviour is something common to them, presumably their internal states--but this does not include the full content of their attitudes. So, given externalism, content does not play an explanatory role after all; it comes out looking epiphenomenal. It is no reply to this argument to point out, correctly enough, that the agents on earth and twin earth are going to buy different liquids, so that there is a match between file:///D|/The%20Character%20of%20Mind%20-...on%20to%20the%20Philosophy%20of%20Mind.htm (79 of 175) [11.07.2007 13:54:08] file:///D|/The%20Character%20of%20Mind%20-%20An%20Introduction%20to%20the%20Philosophy%20of%20Mind.htm what they are doing and their attitudes. The problem with this reply, obviously, is that they would each do exactly the same thing if their contexts were switched: if they were each transplanted to the other planet, their attitudes would cause them to go and buy liquids that did not match their content. -76- The underlying point here is that the two sets of attitudes have the same causal powers, so that they cause agents to do the same things in different environmental contexts. The case is logically analogous to that of a knife that has the power to cut bread: in one context it cuts loaf A, in another loaf B, but there is nothing in its explanatory properties that incorporates the identities of these different loaves. The relevant explanatory property here is simply being sharp, not sharp-for-A and sharp- for-B. A power can act on an object without that object being part of the power. The trouble caused by the twin earth case is that it extrudes content from the causal powers of the agent's attitudes, but then it is not clear how it can play any explanatory role. Compare truth: whether a belief is true makes no difference to its causal powers, since this lies quite outside the believer's causal mechanisms; so it would be absurd to think that an explanatory psychology should concern itself with the truth-value of beliefs in addition to what is believed. The twin earth case seems to show that the same basic reasoning extends to banish external content too. This is a disturbing result--it threatens to undermine the whole practice of explaining actions by means of propositional attitudes, and it bodes ill for a scientific psychology in which content plays an essential part. One way to try to resist the argument is to distinguish broad from narrow content: there is the kind of content specified by concepts like water, which fails to play an explanatory role, but there is another kind that is more internal and hence not open to the twin earth argument. For, intuitively, there is something psychologically in common between me and my twin earth counterpart when we each think about our respective liquids, and this common component is what we are proposing to call narrow content. There are two problems with this proposal, however. The first is that it is not clear that what is common here is really a case of content, i.e. a representational state with genuine truth conditions. It might just be something purely phenomenal, like an objectless feeling, which has nothing propositional about it. On the other hand, if there is something contentful lurking beneath the broad contents--perhaps along the lines of 'transparent, colourless, drinkable liquid'--then the problem is that externalism is also going to be true of this, though only in the second way that we distinguished above. That is, such a content is identified by referring to nonmental properties, such as transparency and drinkability, and it is again unclear how such external items could play a role in file:///D|/The%20Character%20of%20Mind%20-...on%20to%20the%20Philosophy%20of%20Mind.htm (80 of 175) [11.07.2007 13:54:08] file:///D|/The%20Character%20of%20Mind%20-%20An%20Introduction%20to%20the%20Philosophy%20of%20Mind.htm causing the agent's behaviour. The -77- whole problem is that content brings in items that exist outside of the agent, and the question is how they could contribute to causing what the agent does. States of the nervous system, safely nestled within the agent's boundaries, can easily cause the muscle movements in which action consists; but how can the states of affairs mentally represented by an agent contrive to activate his voluntary musculature? Let me mention two other possible escape routes, without attempting to evaluate them in any detail; both have their problems as well as their attractions. One response is to reject the causal model of psychological explanation: true, content plays no causal role in explaining behaviour, but that is not yet to say that it plays no role, since not all explanation is causal. The most promising version of this strategy introduces teleological notions into the picture. The thought here, simply put, is that [ Pobierz całość w formacie PDF ] |