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sentencehood. On the whole, they neither construct such a definition nor, in many cases, I suspect (unfortunately), come to know it. The definition serves to state what a sentence is, and it answers the question: what would it suffice a student to know in order to classify entities as sentences of logic? Davidson asks (Davidson 1994b, p. 126): “What would it suffice an inter- preter to know in order to understand the speaker of an alien language, and how could he come to know it?” He suggests that “a theory of truth, constructed more or less along the lines of one of Tarski’s truth definitions, would go a long way toward answering the first question.” His account of radical interpretation is his answer to the second. A theory of truth for the alien L in the mother tongue would serve as an account of ‘means-in-L-that’ (or almost, at any rate: I leave aside, for example, discussion of sentences that lack truth values – see Davidson 1984 [1967], p. 36). And revealing ‘means-in-L-that’ is one goal of radical interpretation (the complete goal being the attribution of propositional attitudes generally). But the answers to Davidson’s pair of questions might tell us no more about the psychol- ogy of actual interpreters than a recursive definition of sentencehood tells us about the psychology of actual students who know a sentence of logic when they see one. The interest of the questions lies elsewhere, according to him:

. . . I did not say speakers or interpreters actually formulate such theo-

ries [of truth]. It does seem to me, though, that if we can describe how they could we will gain an important insight into the nature of the inten- tional (including, of course, meaning), in particular into how the intentional supervenes on the observable and the non-intentional. (Davidson 1994b, p. 127)

This partial statement of the project should not be misconstrued as committing an obvious fallacy (a detective can describe how a crime could have come about and yet gain no insight into it whatsoever). Davidson lays out certain necessary conditions for interpretation, which include canons that interpreters cannot flout lest they fail to be engaged in interpretation, and restrictions upon the knowledge they acquire. These conditions nar- row the field of potential interpretations; and it is this narrowing that makes interpretation possible. But these conditions need reveal little about the psy- chology of actual interpreters. First, interpreters need not self-consciously obey the canons. Second, the canons do not dictate unique interpretations but merely impose broad restrictions, and nothing is said about the skill re- quired for constructing interpretations. Third, restrictions on knowledge need reveal little about how it is “stored.”

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The truth-theoretic component of Davidson’s project places a re- striction on the knowledge of meaning acquired by interpreters – such knowledge must be expressible (not necessarily by the interpreters) as a theory of truth. At the least, pursuing the aim of expressing a theory of meaning as a theory of truth will teach us much about meaning and truth. And if we achieve this aim, we will have a finite way of recursively stating a theory of meaning for a language, thus satisfying, in principle, two crucial conditions – that interpretations be graspable by finite minds (Davidson 1984 [1966], pp. 8–9), and that compositionality be exposed:

a theory of meaning for a language L shows ‘how the meanings of sentences depend upon the meanings of words’ if it contains a (recursive) definition of truth-in-L. (Davidson 1984 [1967], p. 23)

But in seeing how meaning rests upon truth, we shall not have eliminated the former notion. Just as Tarski (1944) explicitly invokes a prior understanding of the concept of truth simpliciter in formulating his criterion of “material adequacy” for his definition of truth-in-a-language (the prior understanding enables us to see the correctness of this criterion), so Davidson presupposes prior understandings of both ‘true’ and ‘means that’ simpliciter in his attempt to use a theory of truth as a theory of meaning.

The success of the latter project is to be measured in terms of the degree of conformity between the output of the theory of truth concerning the sentences in its domain, and our understanding of what the relevant speakers mean by those sentences. The presupposed understanding of ‘means that’ emerges clearly in the following well-worn problem case:

‘Es regnet’ is true-in-German if and only if: it is raining and 2+ 2 = 4.

Yet ‘Es regnet’ does not mean in German that it is raining and 2+ 2 = 4. From the perspective of a theory of meaning, we might say that the equivalence has arisen via a “deviant” derivation within the truth theory. If a theory of truth is to serve as a theory of meaning, we have to ensure that

S is true in L if and only if p

holds because, and only because, S means in L that p (Davidson 1984b [1973], p. 138). We can, perhaps, ensure this by placing restrictions on permissible derivations within the truth theory. The details of such restric- tions are not my concern here. Rather, I merely want to emphasize that their selection is driven by our prior understanding of ‘means that’.