How Is It Possible That Marshall Is Still Alive After Sraffa’s 1925/1926 Devastating Critique?
Abstract
Even if in 1930 Sraffa ended by asserting that “perhaps I ought to have explained that, in the circumstances, I think it is Marshall's theory that should be discarded”, one of the aims of his renowned 1925/1926 two papers appears to have been (or at least many readers interpreted them in this way) to define the strict conditions for Marshallian partial equilibrium to be theoretically legitimate, i.e. suited to reach rigorously exact conclusions. In other words, he reconstructed in a logically consistent way the Marshallian partial equilibrium model of pure competition markets with reference to the supply curve, in order to single out the logically admissible accounts of empirical situations to which those models could be applied and those situations to which they could not. Note, by the way, that a similar exercise might be done with reference to the demand side too, resulting in the conclusion that partial equilibrium legitimacy requires a unitary income (and/or price) elasticity of demand.In both cases it has to be remarked that in any case every (logically) consistent theory is ‘true’ in its context, usually a variety ‘possible worlds’, independently of actual circumstances. However, its applicability to the ‘real world’ otherwise depends on the relevance of its assumptions.
The main aim of this paper is therefore to show that Sraffa’s attempt, as well as other ones in the same vein for that matter, paves the way for conjecturing the existence of a trade-off between rigor and relevance in economic theorizing, where rigor is a matter of being consistent with theoretical principles, while relevance has to do with the possibility of transferring conclusions or predictions obtained within the model to what actually happens in the external world.