Who has advanced our understanding of capitalism since Marx? I think it is impossible to answer this question briefly. When I try, I start with a short list of "the usual suspects" (though my list might differ from that of others on OPE-L, perhaps.....), and then find myself immediately branching out to recognize the related efforts of many others who have contributed small but important insights. Like Gary, I put Sraffa relatively high up on my list, but not exactly for the reasons he gives. Here's why: Gary writes: >I would have to say Sraffa (surprise!), mainly for showing that the classical >P.E. tradition running through Ricardo to Marx is robust: i.e. its fundamental >insights regarding value and distribution hold up when the problematic labor >value analysis is discarded. He also pointed the way to a critique of the >marginalist theory that displaced classical and Marxian P.E. To me, the validity of the latter statement depends strongly on what one means by "marginalist" theory. Speaking broadly, I would say that Sraffa's "critique" of marginalist theory is only achieved by arbitrarily dismissing or obscuring realistic conditions under which "marginal" considerations *might* plausibly arise. Three examples: 1) Capitalism universally features markets for financial capital and labor power in addition to markets for commercially produced commodities, but the former are not incorporated into formal Sraffian analysis. Thus the "un-marginalist" Sraffian "result" about the relation between wage and profit rates arises in part from begging the question of how these prices (and they are indeed prices, in addition to representing claims on total product) are determined in their respective markets. 2) The standard Sraffian model presumes that Leontief (fixed-coefficient, constant returns to scale) production conditions obtain universally. Whether this condition reasonably describes actual capitalist economies is a matter of debate, but in analytical terms it is extremely restrictive. In particular, Leontief can be understood as the limiting case of a more general constant elasticity of substitution production function, and in every instance of this function *except* the limit as the elasticity parameter approaches infinity, factors are substitutable at the margin, and thus "marginalist" considerations would presumptively apply. 3) The standard Sraffian model also imposes rather stringent market conditions, without providing any formal grounds for understanding when and why they might obtain. In particular, it is assumed that the "law of one price" holds throughout, even in the (otherwise unanalyzed!) markets for capital and labor power. If you were to ask what sort of economic behavior would make this strong condition tenable, the only answer I know of would be arbitrage: market participants taking advantage of non-cost-based price differentials by shifting their choices of quantities demanded and supplied. But arbitrage is a form of optimizing behavior, and what's more it necessarily involves optimizing *at the margin*--otherwise price differentials would not be driven to zero, as the Sraffian model presumes. So if the model implicitly presumes marginalist optimizing behavior here, on what legitimate grounds does it categorically rule this behavior out in other plausible contexts? [Related thought experiment: Marx's analytical "base case," employed subsequent to V. I Ch. 5 of Capital, presumes that commodity prices are proportional to their respective values. Sraffian analysis replaces this basic scenario with one in which the law of one price obtains universally, but commodities typically do not exchange at their respective values. As Marx notes in the last footnote of Ch. 5, neither representation describes actual capitalist market outcomes. On what grounds *intrinsic to the theory* could one justify invoking the Sraffian in preference to the Marxian base case? ] Moreover, and more importantly, "marginalist" analysis, in the sense of taking derivatives of production, cost, or utility functions, is not the essence of *neoclassical* theory as it has developed in the 20th century. Which leads me to the next point: >The contribution was both positive and critical: he gave us a reason to stick >with classical P.E. (the theory holds up) and a reason to ditch neoclassical >theory (it DOESN'T hold up). I don't see this claim at all, since by the second welfare theorem, any market outcome generated by the Sraffian model could be supported as a solution of a neoclassical general equilibrium market model, and moreover one with Leontief production for which no derivatives are taken anywhere (so no "marginalist" conditions arise, in that limited sense). Thus any valid *positive* outcome emerging from the Sraffian model (as opposed to the "results" that emerge from simply failing to incorporate certain real-world markets or implicit behavioral assumptions) can also be demonstrated with the appropriately specified neoclassical general equilibrium model, with the important difference that in the latter the grounds for restrictive conditions such as the "law of one price" emerge from explicitly stated underlying conditions (conditions, by the way, that are never ruled out by Marx or Sraffa). For example, as Mas-Colell has demonstrated, one can readily generate "reswitching" phenomena in a standard neoclassical GE model. In light of this, I wonder how Sraffian analysis can be used to demonstrate that neoclassical theory "doesn't hold up," or for that matter that classical theory "holds up" any better. Gil
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