Introduction: Davidson’s philosophical project Ernie Lepore and Kirk Ludwig Donald Davidson’s work has had a pervasive influence on analytic philosophy throughout the last half century. His contributions lie primarily in the theory of meaning, the philosophy of mind and action, epistemology, and metaphysics. This volume focuses on themes connected with his work in the theory of meaning, philosophy of mind, and epistemology. The introduction first provides an overview of Davidson’s work. We pay special attention to his work on truth-theoretic semantics and its integration with the project of radical interpretation, his conception of the nature of mental states, and his account of our knowledge of things around us and of our own minds. This will set the stage for a brief overview of the more detailed examinations of particular themes connected with Davidson’s work that follow. 1 Truth-theoretic semantics In a series of papers in the 1960s and 1970s, beginning in 1965 with “Theories of Meaning and Learnable Languages” (Davidson 2001a) and in 1967 with “Truth and Meaning” (Davidson 2001c), Davidson introduced and defended one of the few really novel approaches to the theory of meaning in the latter half of the twentieth century. Central to his proposal was the suggestion that an axiomatic truth theory modeled after the truth definitions that Tarski showed how to construct for formal languages could be used to give what he called “a constructive account of the meaning of the sentences” in a natural language (Davidson 2001a, p. 3). The exact import of David- son’s suggestion and whether he took himself to be pursuing a traditional project in a novel way, a reduction of meaning to truth conditions, or urging a reform of the aims of semantics, has been a matter of controversy. For example, the paper by Gary Ebbs in this volume takes issue with the interpretation offered in our 2005 book (Lepore and Ludwig 2005) over whether Davidson was pursuing a novel approach to illuminating what it is for words to mean what they do or engaging in a project of Carnapian explication (see also the exchange in (Soames 2008; Lepore and Ludwig 2011)). For 2 ERNIELEPOREANDKIRKLUDWIG purposes of initial orientation, we will sketch the account of Davidson’s project we offered in (Lepore and Ludwig 2005) and return later to the interpretive issues in discussion of contributions to the volume. Davidson’s starting point in the theory of meaning is the observation that natural languages must be compositional. By this we mean that they divide into semantically primitive expressions and semantically complex expressions that are understood on the basis of the semantical primitives and their mode of combination. Davidson argued that it was a condition on natural languages being learnable by finite speakers that they be compositional and have a finite number of semantical primitives (Davidson 2001a, pp. 8–9). This is perhaps a natural observation, but it is one which Davidson pointed out was often violated by extant proposals for analyzing various natural language locutions (ibid., pp. 9–13). The observation that natural languages are compositional gives rise to the requirement that any theory of a natural language should give an account of the roles of significant expressions in the larger expressions in which they are used. The question is how to present such an account. Prima facie, such an account should start with axioms for semantically primitive expressions a language L that (i) give their meanings and (ii) enable one to derive for each sentence s in L a theorem of the form (M). (M) s means that p A natural approach, looking back to Frege (Frege 1997), is to introduce entities to serve as the meanings of expressions with which they are associated. The meanings associated with complex expressions can then be treated as constructed out of the entities associated with primitive expressions, and expressions of the form “that p” would be taken to refer to the meanings of sentences. Davidson took a dim view of this, for reasons it would take us too far afield to detail (Davidson 2001c, pp. 17–22; Lepore and Ludwig 2005, ch. 3), and he suggested that formulating a logic to deal with substitu- tions into the position of “p” in “s means that p,” when it is treated intensionally, would require already solving the problem of giving a compositional meaning theory, since such substitutions would have to be licensed on the basis of judgments about sameness of meaning over a class that includes complex expressions. At this point, Davidson suggested a radical break with traditional approaches. As Davidson put it: Anxiety that we are enmeshed in the intensional springs from using the words “means that” as filling between description of sentence and sentence, but it may be that the success of our venture depends not on the filling, but on what it fills. The theory will have done its work if it provides, for every sentence s in the language under study, a matching sentence (to replace “p”) that, in some way yet to be made clear, “gives the meaning” of s. One obvious candidate is just s itself, if the object language is contained in the metalanguage; otherwise a translation of s in the metalanguage. As a final bold step, let us try treating the position occupied by “p” extensionally: to implement this, sweep away the obscure “means that,” provide the sentence that replaces “p” INTRODUCTION: DAVIDSON’ S PHILOSOPHICAL PROJECT 3 with a proper sentential connective, and supply the description that replaces “s” with its own predicate. The plausible result is (T) s is T if and only if p What we require of a theory of meaning for a language L is that without appeal to any (further) semantical notions it place enough restrictions on the predicate “is T” to entail all sentences got from schema T when “s” is replaced by a structural description of a sentence of L and “p” by that sentence. (Davidson 2001c, p. 23) Davidson notes that the condition placed on (T) “is in essence Tarski’s Convention T that tests the adequacy of a formal semantical definition of truth” (ibid.), and so the result of focusing on getting the right relation between the sentence s and the sentence that goes in the place of “p” in “s means that p,” but with an extensional “filling,” is to require that we have a truth theory for the language that meets Tarski’s requirement of adequacy. Davidson, as can be observed in the above passage, immediately goes on to suggest that one can put constraints on a truth theory that will ensure that it meets Convention T (or a suitable analog for a natural language) without appeal to any semantic concepts apart from concepts drawn from the theory of reference (truth, satisfaction, and reference). As we read Davidson, this is an extension of the project of providing a constructive account of natural languages, which looks beyond illuminating the relation between semantical primitives and complexes to showing something about how the concept of meaning is related to other concepts. On this account, Davidson hoped initially to show that an axiomatic truth theory adapted to a language with context sensitive elements would satisfy an appropriate analog of Convention T if it were merely true, because of the added sensitivity required for the theory to predict correctly the truth of sentences containing demonstratives, among other context sensitive elements, in such sentences as “This is grass,”“This is snow,”“This is white,” and “This is green.” This would rule out, for example, such spurious T-sentences as: “Snow is white” is true for a speaker at t iff grass is green at t. In (Lepore and Ludwig 2005, chs. 4, 5, and 9) we show that the initial and the extended project can be separated, and that it suffices to carry out the initial project to have a certain body of knowledge about a truth theory, roughly: (i) that its axioms use metalanguage expressions in giving satisfaction and truth conditions that interpret the object language terms for which they are used to give satisfaction conditions; (ii) what the axioms as given by the theory mean; (iii) a grammar for the language of the truth theory to be used in connection with (iv) a canonical proof procedure that draws only on the content of the axioms in proving T-sentences. 4 ERNIELEPOREANDKIRKLUDWIG If the axioms meet condition (i), we will call them and the theory they determine interpretive. (i)–(iv) do not involve the assertion of the axioms of the truth theory, and the language in which they are stated need not be the language of the truth theory. They are supposed to state knowledge that anyone could have about a truth theory that would suffice to use it to interpret object language sentences. This does require being in a position to understand the truth theory. (ii) and (iii) are supposed to secure this: knowing what the axioms mean and having a grammar for the language of the truth theory, we are in a position to come to know the language of the truth theory. Given this: if one knows (i)–(iv) about a truth theory, one is in position to derive a T-sentence, “s is true iff p” (ignoring context sensitivity for the sake of simplifying exposition) for any object language sentence s, which draws only on the content of the axioms. Knowing this, we know that “p” in the theorem translates s. Knowing this, we know that the corresponding instance of (M) is true. Understanding the language of the truth theory, we are then able to infer from (M) being true to its being the case that s means that p.