Non-ergodic (in Place of Stationary, Timeless) Economic Systems: Considerations Suggested by Joan Robinson’s Distinction between Two ‘Notions’ of Time in Economic Theory

Abstract

In seeking our path among the complex of questions raised by the fourth characteristic ascribed by Luigi Pasinetti to the Cambridge School (notoriously, questions pertaining to the ‘treatment of time’ stem in all directions and are reflected in practically any part of an economic theory), we believe it is convenient to start from a point Pasinetti himself refers to in his discussion of that characteristic: namely, the ‘sharp distinction made by Joan Robinson between logical time and historical time’ (Pasinetti, 2007, p. 226). The reason is the following. Originally, the distinction was proposed to give evidence to certain elements whereby the neoclassical theory would fail to give a satisfactory account of a process of capital accumulation. As we shall see, these are basically, though by no means exclusively, elements preventing a full recognition of the degree of irreversibility (‘non-ergodicity’) that would be the feature of certain economic processes, changes in ‘logical’ time being prevalently used by Robinson as a metaphor for perfectly reversible changes. The fact is, however, that at a certain point Robinson felt that the criticisms she had raised against the neoclassical theory should also be directed against the classical theory, at least in the version we find in Piero Sraffa’s Production of Commodities: ‘The specification of a selfreproducing ... system such as that of Sraffa ... is in logical time, not in history (Robinson, 1974 [1978], p. 128). This has understandably resulted in, or has possibly given expression to, a fundamental division within what Pasinetti calls the Cambridge School; and it is for this reason that, although the question has already been addressed a number of times and without being able to cover the vast literature that has accumulated on the subject, we feel that we should start our comment from this particular point.