Kurz (2002: 184–185) and Kurz and Salvadori (2010) prove that this is not the case, even if some Post Keynesians sympathetic to Marxism argue that Sraffa showed how to determine the rate of profit independently of prices as a share of a particular composite commodity (akin to Smith’s idea of labour commanded).
But with respect to the classical and orthodox Marxist labour theory of value, Sraffa in fact thought that it was a “corruption” of an earlier and better “physical real cost theory” (Kurz 2002: 185).
In an unpublished note of 1928, Sraffa gave his damning verdict on the labour theory of value:
“There appears to be no objective difference between the labour of a wage earner and that of a slave; of a slave and of a horse; of a horse and of a machine, of a machine and of an element of nature (?this does not eat). It is a purely mystical conception that attributes to human labour a special gift of determining value. Does the capitalist entrepreneur, who is the real ‘subject’ of valuation and exchange, make a great difference whether he employs men or animals? Does the slave-owner?” (Sraffa, unpublished note, D3/12/9: 89, quoted in Kurz and Salvadori 2010: 199).Bravo, Piero. Michał Kalecki had a similarly negative view and rejected the labour theory as utterly metaphysical. So did Joan Robinson, whose rejection of it was scathing (Robinson 1964: 28–46).
The point Sraffa made is a profound one too. Why should human labour have a special status when animal labour has been – and in some countries still is – a fundamental factor of production? (as a kind of special category of capital good). What about natural forces like winds driving windmills? All these things produce labour power too, and if Marx’s abstract socially-necessary labour time (SNLT) units were meaningful measures of every type of heterogeneous, concrete human labour, then the labour power done by animals or nature ought to be measurable in terms of SNLT units too.
So why is human labour the sole source of value? Why not animal labour time too, but translated into abstract SNLT? Why not wind power translated into abstract SNLT?
Kurz, Heinz D. 2002. “Sraffa’s Contributions to Economics. Some Notes on his unpublished Papers,” in Sergio Nistico and Domenico Tosato (eds.), Competing Economic Theories. Essays in Memory of Giovanni Caravale. Routledge, London. 177–195.
Kurz, Heinz D. and Neri Salvadori. 2010. “Sraffa and the Labour Theory of Value: A Few Observations,” in John Vint et al. (eds.), Economic Theory and Economic Thought: Essays in Honour of Ian Steedman. Routledge, London and New York. 189–215.
Robinson, Joan. 1964. Economic Philosophy. Penguin, Harmondsworth.
Vernengo, Matias. 2012. “Sraffa and Marxism or the Labor Theory of Value, what is it good for?,” Naked Keynesianism, August 14