By far the most interesting and successful recent theories of meaning have been truth conditional. The paradigm of such theories is usually taken to be Tarski's recursive characterization of truth for certain formal languages.¹ Donald Davidson has both practiced truth-conditional theorizing in the semantics of natural languages, and has pleaded for the general importance of truth-conditional semantics.² What is even more interesting and more unique to him, Davidson has sought to give a deeper motivation — perhaps a foundation — for truth-conditional semantics of the kind pioneered by Tarski. This deeper foundation Davidson has sought in the requirement of the learnability of the language in question.³