Online research in philosophy

In this paper I argue against Twin-Earth externalism. The mistake that Twin Earth arguments rest on is the failure to appreciate the force of the following dilemma. Some features of things around us do matter for the purposes of conceptual classification, and others do not. The most plausible way to draw this distinction is to see whether a certain feature enters the cognitive perspective of the experiencing subject in relation to the kind in question or not. If it does, we can trace conceptual differences to internal differences. If it doesn’t, we do not have a case of conceptual difference. Neither case supports Twin Earth externalism.

A content of a subject's mental state is narrow when it is determined by the subject's intrinsic properties: that is, when any possible intrinsic duplicate of the subject has a corresponding mental state with the same content. A content of a subject's mental state is..

The subject of this paper is the debate between externalism and internalism about mental content presented by Tim Crane in Chapter 4 of his book Elements of Mind. Crane’s sympathies in this debate are with internalism. The paper attempts to show that Crane’s argumentation is not refuting the Twin Earth argument and externalism, and that in its basis it does not differ much from externalism itself Crane’s version of the argument for externalism features two key premises: (1) The content of a thought determines what the thought is about/what it refers to (the Content Determines Reference Principle); and (2) Twins are referring to different things when they use the word “water”. From these, in a few simple steps, Crane’s externalist infers: Therefore, their thoughts are not “in their heads”. Crane suggests denying the Content Determines Reference Principle in the light of indexical thoughts. In the first stage, Crane reduces “content” to “some aspect of content”, although he needs all aspects of content to secure identity of thoughts. However, his view then comes close to something acceptable to externalists. In the second stage, Crane makes content relative to context, but then reference still determines content.

Controversy continues to attach to the question whether an externalism about mental content is compatible with a traditional doctrine of privileged self-knowledge. By an externalism about mental content, I mean the view that what concepts our thoughts involve may depend not only on facts that are internal to us, but on facts about our environment. It is worth emphasizing, if only because it is still occasionally misperceived, that this thesis is supposed to apply at the level of sense and not merely at that of reference: what concepts we think in terms of -- and not just what they happen to pick out -- is said by the externalist to depend upon environmental facts. By a traditional doctrine of privileged self-knowledge, I mean the view that we are able to know, without the benefit of empirical investigation, what our thoughts are in our own case. Suppose I entertain a thought that I would express with the sentence `Water is wet'. According to the traditional doctrine, I can know without empirical investigation (a) that I am entertaining a thought; (b) that it has a particular conceptual content, and (c) that its content is that water is wet.

Controversy continues to attach to the question whether an externalism about mental content is compatible with a traditional doctrine of privileged self-knowledge. By an externalism about mental content, I mean the view that what concepts our thoughts involve may depend not only on facts that are internal to us, but on facts about our environment. It is worth emphasizing, if only because it is still occasionally misperceived, that this thesis is supposed to apply at the level of sense and not merely at that of reference: what concepts we think in terms of -- and not just what they happen to pick out -- is said by the externalist to depend upon environmental facts. By a traditional doctrine of privileged self-knowledge, I mean the view that we are able to know, without the benefit of empirical investigation, what our thoughts are in our own case. Suppose I entertain a thought that I would express with the sentence `Water is wet'. According to the traditional doctrine, I can know without empirical investigation (a) that I am entertaining a thought; (b) that it has a particular conceptual content, and (c) that its content is that water is wet.

In this paper I try to make as much sense aspossible of, first, the extensive philosophicalliterature concerned with the status of `Wateris H2O' and, second, the implications ofPutnam's invention of Twin Earth, anotherpossible world stipulated to be just like Earth, except that water is XYZ, notH2O.

1. In the course of his philosophical development, Jerry Fodor has indicated two sorts of non-broad (i.e., non-truthconditional) content of mental representations, namely content of mental state types opaquely taxonomized (de dicto content: DDC) and narrow content (NC) qua mapping function from contexts (of thought) to broad contents. According to the former conceptualization, mental state tokens which are truth-conditionally identical may be such that they cannot both truthfully ascribed to one and the same subject at the same time, for they differ in their respective DDC. In Fodor's own example, Oedipus' thoughts that he will marry Jocasta and that he will marry Mum are truth-conditionally identical, but different as far their DDC is concerned; one cannot indeed truthfully ascribe both thoughts to him simultaneously1. According to the latter conceptualization instead, mental state tokens of molecularly identical twins placed in different environments (such as Earth and Twin-Earth) are such that, although they differ in their truth-conditions, they share the same NC2. For instance, these twins respectively think that water quenches thirst and that twater (a liquid similar to water but its chemical composition) quenches thirst. Although these thoughts thus differ in broad content, they have the same NC: had the Twin-Earthling twin been brought up on Earth rather than on Twin-Earth where he actually lives, he would have thought that water quenches thirst rather than that twater quenches thirst3. According to Fodor's picture, both concepts are invoked for the purpose of psychology in order to account for one and the same thing, namely subjects' behavior. On the one hand, difference in behavior of a subject whose thought-tokens have the same truth-conditions may be ascribed to difference in the DDC of these tokens4. On the other hand, identity in behavior between two molecularly identical subjects whose thought-tokens have different truth-conditions is explained in terms of the NC- identity of these tokens5..

In response to Kripke's modal argument contemporary descriptivists suggest that referring terms, e.g., ‘water’, are synonymous with actually-rigidified definite descriptions, e.g., ‘the actual watery stuff’. Following Scott Soames, this strategy has the counterintuitive consequence that possible speakers on Perfect Earth cannot be ascribed water-beliefs without beliefs about the actual world. Co-indexing the actuality and possibility operators has the equally untoward result that possible speakers on Twin Earth are ascribed water-beliefs. So, Soames's dilemma is that the descriptivist can account for either Twin Earth or Perfect Earth but not both. In response, this paper argues that since ‘actual’ is an indexical, the content of water-beliefs is egocentric, and so if the descriptivist avails herself of relativized propositions as the content of such beliefs, she is able to account for both Twin Earth and Perfect Earth. The lesson is that we have to tread carefully when making inferences about the contents of beliefs from the semantics of belief-reporting sentences that contain actually-rigidified expressions.