Physicalism, Introspection, and Psychophysics: The Carnap/Duncker Exchange

Uljana Feest

Technical University Berlin

In 1932, Rudolf Carnap published his article “Psychology in a Physical Language,” in which he laid out the idea that all first-person experiential reports can be translated into a “physical” language (Carnap 1932a). For Carnap, this was a direct continuation of his earlier project of overcoming metaphysics by means of an analysis of language (Carnap 1931a) and his attempt to specify a universal (physical) language as the language of choice (Carnap 1931b). Moreover, since Carnap’s method of overcoming metaphysics had made appeal to empirical criteria of meaningfulness, an obvious question was, what were conditions of verifiability for experiential statements themselves. Carnap’s views about the possibility of a universal, physical language may be viewed as responding to this question. It is well known that Carnap’s article gave rise to what is referred to as the “protocol-language debate” within the Vienna Circle (e.g., Neurath 1932; see also Uebel 2007). Another question has received less attention in the literature, however, namely how it was received by psychologists, and – more generally – how the project of physicalizing psychology fit in with the kind of scientific psychology practiced at the time. A good entry into these issues is provided by a brief exchange between the Gestalt psychologist Karl Duncker (1932) and Rudolf Carnap (1932b), which is characterized by a surprising degree of mutual incomprehension, with Duncker suggesting that Carnap’s critique of (introspective) psychology was attacking a strawman and Carnap saying that Duncker had completely missed his point. In this paper I will analyze this exchange. I will argue that while it is true that Duncker perhaps misunderstood the philosophical motivation behind Carnap’s article, it is also easy to appreciate Duncker’s puzzlement, since the kind of physicalizing approach that Carnap was pushing had at this point long been practiced within the (Fechnerian/Machian) psychophysical tradition of experimental psychology, which Gestalt psychology was also rooted in, thus raising the question whether it was inspired by this tradition. I will argue that we can contextualize Carnap’s proposal about a physicalized psychology within the history of psychology, though this does not necessarily mean that he knew of (or cared about) the details of the psychological work being done at the time. (see also Feest 2007).