On the Logical Positivists' Philosophy of Psychology: Laying a Legend to Rest

The received view in the history of the philosophy of psychology is that the logical positivists—Carnap and Hempel in particular—endorsed the position commonly known as “logical” or “analytical” behaviourism, according to which the relations between psychological statements and the physical-behavioural statements intended to give their meaning are analytic and knowable a priori. This chapter argues that this is sheer legend: most, if not all, such relations were viewed by the logical positivists as synthetic and knowable only a posteriori. It then traces the origins of the legend to the logical positivists’ idiosyncratic extensional or at best weakly intensional use of what are now considered crucially strongly intensional semantic notions, such as “translation,” “meaning” and their cognates, focussing on a particular instance of this latter phenomenon, arguing that a conflation of explicit definition and analyticity may be the chief source of the legend. 1. The Legend Near the beginning of his recent Carnapian book Constructing the World, David Chalmers rightly remarks that “A surprising and often-overlooked feature of the Aufbau is that Carnap there requires only that definitions be extensionally adequate” (Chalmers 2012, p. 4). Chalmers then points out that in the 1961 preface to the second edition of the Aufbau (Carnap 1928/1961), Carnap “says that the definitions should be held to a stronger, intensional, criterion of adequacy” (Chalmers 2012, p. 5). Chalmers goes on to give “analyticity, apriority and necessity” as examples of stronger criteria (obviously intending the necessity in question to be logical or metaphysical necessity). It is clear from the preface, however, that Carnap did not demand such strongly intensional criteria, but only that the coextensiveness of the definiendum and definiens not be merely “accidental, but necessary, i.e., it must rest either on the basis of logical rules or on the basis of natural laws” (Carnap 1928/1961, * Dedicated to the memory of Rachel Jardine.