Thomas Kuhn and the Causal Theory of Reference

It is typically held that Thomas Kuhn was committed to a descriptivist view of the meaning of theoretical terms, and that his most infamous thesis – incommensurability – was a consequence of this. The causal theory of reference supposedly rules out incommensurability by allowing the extension of a term, rather than merely the intension, to (at least partly) constitute the meaning of the term, thereby ensuring that part of the ‘meaning’ remains constant across theory changes. It is therefore surprising to find Kuhn endorsing aspects of the causal theory in several later essays while still maintaining the possibility of incommensurability. This paper will investigate how Kuhn understood both the causal theory and incommensurability, such that his endorsement of both was not the bald-faced contradiction it would be according to the standard reading. In fact, many of the affinities of Kuhn’s view with the causal theory are part of what make incommensurability possible, or so I will argue. More generally, I will suggest that Kuhn should be thought of as rejecting the very idea that the meaning of scientific terms is some aggregate of extension and intension, or sense.