The cogito ergo sum of Descartes is one of the best-known (and simplest) of all philosophical formulations, but ever since it was first propounded it has defied any formal accounting of its validity. How is it that so simple and important an argument has caused such difficulty and such philosophical controversy?

In this pioneering work, Jerrold Katz argues that the problem with the cogito lies where it is least suspected--in a deficiency in the theory of language and logic that Cartesian scholars have brought to the study of the cogito. Katz contends that the laws of...

Sense, Reference, and Philosophy develops the far-reaching consequences for philosophy of adopting non-Fregean intensionalism, showing that long-standing problems in the philosophy of language, and indeed other areas, that appeared intractable can now be solved. Katz proceeds to examine some of those problems in this new light, including the problem of names, natural kind terms, the Liar Paradox, the distinction between logical and extra-logical vocabulary, and the Raven paradox. In each case, a non-Fregean intentionalism provides a philosophically more satisfying solution.