Abstract
While the idea that thinking is a form of silent self-talk goes back at least to Plato, it is not immediately clear how to state this thesis precisely. The aim of the paper is to spell out the notion that we think in language by recourse to recent work on inner speech. To that end, inner speech and overt speech are briefly compared. I then propose that inner speaking be defined as a mental episode that substantially engages the speech production system; the underlying model of speech production is sketched. Next, the cognitive role of inner speaking is explored, especially its role in thinking and reasoning. The question of whether it is a way of making thoughts accessible (to whomever) or whether it is a means of thinking itself is raised. I argue that there are two reasons for assuming that, occasionally, we think in language. More specifically, I will claim that some instances of thinking are instances of inner speaking as they exploit certain properties of natural language, and that some instances of inner speaking are instances of thinking as they play a decisive role in paradigmatic cases of thinking that result from internalizing and re-using certain social-linguistic practices. Finally, the Language-of-Thought hypothesis as an alternative account is critically discussed.