Part I of this trilogy, Historical and Scientific Setting, set out a general context for selecting a certain subclass of inter-theoretic relations as achieving appropriate explanatory and ontological unification – hence for properly being labelled reductive. Something of the complexity of these relations in real science was explored. The present article concentrates on the role which identity plays in structuring the reduction relation and so in achieving ontological and explanatory unification.

I defend the correspondence theory of truth, according to which a statement’s truth consists in a relation of correspondence with extralinguistic fact. There are well-known objections to this view, which I consider and rebut, and also important rival accounts, principal among which are so-called deflationist theories and epistemic theories. Epistemic theories relate the concept of truth to our state of knowledge, but fail, I argue, to respect the crucial distinction between a criterion of truth and the meaning of truth: the (...) view that one cannot do semantics, or metaphysics, without addressing epistemic issues is rejected by this work. Against epistemic theories, I illustrate how truth is independent of epistemic considerations. Deflationism is the more popular of the rival accounts and has gained considerable momentum over the past two decades. It is therefore dealt with in greater detail by this work. Deflationist theories exploit the paradigmatic ‘“Snow is white” is true iff snow is white’ biconditional to argue for an insubstantialist account, according to which truth is conservative with respect to non-semantical facts. On this view, truth’s raison d’être is merely to perform the useful expressive function of generalising over possibly infinite sets of assertions. Against deflationist theories, I claim that the work done by Jeffrey Ketland and Stewart Shapiro conclusively demonstrates how truth is informationally additive over non-semantic facts, while deflationism itself is also an excessively impoverishing theory, inadequate to the tasks it purports to accomplish. This work also defends the thesis that Alfred Tarski’s well-known theory of truth is an authentic correspondence theory. To say this is to say that the clauses of a Tarskian truth-definition can be interpreted in terms of a relation of correspondence that holds between true sentences and the states of affairs they describe. I provide a precise account of what the correspondence in question consists in, claiming that true sentences are homomorphic images of facts, i.e. a true sentence represents, in a form-preserving manner, the truth-making facts in it. This gives precise expression to Wittgenstein’s thesis that true sentences picture the world. (shrink)