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domain (the nonnegative reals, in the case of length) that preserves rele- vant structure (in the case of length, the longer the object, the greater the associated real).

The basic idea of Davidson’s analogical strategy is clear enough (Davidson 2001 [1989]). We use sentences to track the propositional at- titudes of an agent; we use the reals to track the lengths of objects. The sentences in the former attribution play the role of the real numbers in the latter. We might maintain that there is an “indeterminacy of length”: there are infinitely many serviceable schemes for attributing lengths. Similarly, there are many serviceable schemes for attributing meanings and the other attitudes to a given interpretee. And the latter indeterminacy is as benign as the former. But the details of the analogy need spelling out.

Davidson does not deny that there are many disanalogies between the two cases. There is, for example, an algorithm for moving from one scale of length measurement to another (multiply by the relevant positive constant); there is no such algorithm in the case of interpretations. However, we do need at least the following. In the measurement theoretic case, we map to numbers from an underlying framework that is invariant between scales. Thus, in the case of using sentences to attribute attitudes, we need to identify an underlying framework that is invariant across the various schemes of interpretation. The invariant framework must consist of relata and relations between them. In the case of length, we have objects standing in the relation ‘is at least as long as’. Infinitely many different mappings of the objects to the reals will serve to track the relation, but the objects and the relation do not vary across the mappings.

In the case of attitude attributions, I shall concern myself only with the relevant relata. It might initially appear that the invariant relata are the propositional attitudes of the interpretee. However, this cannot be. The relata cannot comprise the propositional attitudes themselves, since we identify propositional attitudes by the sentences we use to track them. (In measuring length, we use numbers to measure the relata, not to identify them.) And it is precisely the assignment of these sentences that varies between schemes of interpretation. On Davidson’s picture, indeterminacy is simply the fact that we can use different locutions to locate the same node in some pattern. But what are the invariant nodes? They cannot be propositional attitudes: the belief that P, say, under one scheme, will be the belief that Q under another – two different propositional attitudes (both attributions are couched in the one idiolect of the interpreter).

One might wonder whether there is not some “neutral” way of identi- fying propositional attitudes – so that, despite appearances to the contrary,

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the belief that P and the belief that Q are in fact the same belief. This runs counter to the Davidsonian picture, however. For example, attitudes in one scheme need not map one-to-one onto attitudes in another. Perhaps it is possible that behavior interpreted as a signal could equally well be inter- preted, under a different scheme, as a simple scratch. And signals require more propositional attitude states than simple scratches.

Matthews (1994) might appear to provide a way out. In the case of length, the “empirical relational system” to be represented comprises ob- jects and the qualitative relation ‘is at least as long as’. And the “representa- tion space” (the space that is to represent the empirical relational system, to which that empirical system is mapped) comprises the real number system. In the case of the attitudes, Matthews supposes that there is a substrate of propositional attitudes to be “measured” (these are the invariant relata), al- though he (sensibly) leaves open the issue of exactly which relations among the attitudes are to be represented. He argues that the appropriate repre- sentation space for representing the propositional attitudes comprises a set of “ordered pairs <ai, <sj, rk>>, consisting [of ] an attitude-type ai and what [he calls] a designated proposition<sj, rk>, where rk is a Russellian proposition and sj a sentence-type, a token of which in a particular (un- specified) context serves to designate (express) that Russellian proposition” (Matthews 1994, p. 136).

What is it for there to be two different scales of propositional attitude measurement on Matthews’s account? He furnishes the following example: Suppose that Smith describes the man that he knows only by the name ‘Tully’ as being destitute by saying, ‘Tully is destitute’. I might explain Smith’s remark to someone who knows Tully only as ‘Cicero’ by saying, ‘Smith believes that the wealthy Cicero is destitute’, thereby conveying not simply that Smith is mistaken in his belief, but also who his belief is about, namely, the man that my interlocutor knows only as ‘Cicero’. In the context, the representations associated with sentence types Tully is destitute and the wealthy Cicero is destitute, both of which share the same attitude- type and Russellian proposition, represent one and the same belief. In a different explanatory context, e.g., one in which Smith’s actual words were important, these same representations might represent different beliefs. (Matthews 1994, p. 143)

As Matthews correctly notes, the context dependence here marks a differ- ence between his account of propositional attitude “measurement” and the measurement of length. Nevertheless, suppose we concede that in the first explanatory context in the cited passage we have one belief mapped to two