Piero Sraffa - Free

88 Piero Sraffabeing invariant to changes in the techniques of production and in thedistribution of national income. Sraffa shows that the problem canbe solved only if the two functions are distinguished, focusing on thesecond one in isolation. The standard commodity is invariable (in thespecific sense given above) with respect to changes in the distributionof income on the assumption of a given technology. The standard commodity,however, changes with changes in the techniques of productionin the basic industries.Thus one problem about the relations of exchange can be solved, andthe solution clearly shows how utterly different it is from the metaphysicalproblem concerning the nature of value, or ‘absolute’ value. Sraffa’scontribution from this point of view is that of clarifying the exact relationsought by Ricardo, as well as the limits of the solution to Ricardo’sdilemma and, implicitly, the difference between this issue – which issusceptible to analytical treatment and has a well-defined solution – andthe issue addressed by Marx in his labour theory of value. 165.4 Standard commodity, labour commandedand the von Neumann systemAnother problem related to the standard commodity is a curiosum inthe history of economic analysis that is pointed out by Sraffa himself(1960: 94) in his ‘References to the literature’: namely the fact that thestandard commodity, identified in analysing a ‘Ricardian’ problem,has a strong connection to labour commanded, that is the standard ofmeasure proposed by Smith and strongly opposed by Ricardo himself.The curiosum is considered here not only for its intrinsic importancebut also as an illustration of a more general issue, namely the dangersof attributing decisive importance to merely formal resemblances, withoutpaying attention to possible substantial differences in the problemsunder analysis. Transferring mechanically the mathematical aspects of atheory from the problem for which the theory was originally intendedto a different issue can cover up basic conceptual difficulties.The Standard Commodity 89The analytical similarity between the standard commodity andSmith’s ‘labour commanded’, pointed out by Sraffa, is not in itself verysurprising and the demonstration that he gives is extremely simple. AsSraffa suggests, we may replace the standard net product as the unitof measure with ‘the quantity of labour that can be purchased by thestandard net product’. This magnitude ‘will vary inversely with thestandard wage and directly with the rate of profits’, but ‘according to asimple rule which is independent of prices’. It is a measure by definitionequivalent to the standard net product, namely to a certain amount ofthe standard commodity, and, obviously, it has the same properties; inparticular, a linear relation holds between the rate of profits and thewage when the wage is measured in terms of it. 17What is ‘surprising’ is the fact that Sraffa, in an attempt to find asolution to a Ricardian problem associated with relations of exchange,should come up with a standard of value similar to that which had beenproposed by Smith for its usefulness in dealing with a different problem,that of economic growth. This might in fact be taken as indicative ofthe links existing between the different problems, although they canonly be solved in separation.Besides the similarities between the two standards of measure – Sraffa’sstandard commodity and Smith’s ‘labour commanded’ – there is a parallelsimilarity between Sraffa’s standard system and the system of proportionalgrowth developed by von Neumann. 18 In both cases, the output and themeans of production are composed of the same commodities in the sameproportions. However, this superficial similarity between Sraffa’s standardsystem and the von Neumann system of proportional growth conceals avery substantial difference in the purpose the two theoretical constructionswere intended to serve. Sraffa’s system is part of the search for astandard of measure endowed with particular properties. Von Neumann’ssystem is related to the search for an equilibrium growth path whichwould produce the maximum possible rate of growth for an economicsystem with no technical progress and constant returns to scale. Sraffa’ssystem is linked to the study of relative prices; von Neumann’s has pri-16The first to notice that Sraffa’s conception of the function of the standard ofmeasure is notably more restrictive than the original Ricardian conception isNapoleoni (1961: 109–12). However, he gives a different explanation, and a different(negative) judgement from that proposed here. An explanation similar tothat adopted here is given by Meldolesi (1966). The need for closer specificationof Ricardo’s problem, discussed by Sraffa (1951), is investigated analytically, asseen above, by Garegnani 1960. In § 5.5 the differences between the standardcommodity and the ‘average commodity’ of Ricardo and Marx will be discussed.17Sraffa (1960: 32), cf. also the demonstration given by Gilibert (1972).18Von Neumann, (1945–6). This is perhaps the most important of the cases Sraffaobliquely refers to in his Preface: ‘Others have from time to time independentlytaken up points of view which are similar to one or other of those adopted in thispaper and developed them further or in different directions from those pursuedhere’ (Sraffa 1960: vi). The other case of major interest is Leontief’s input-outputscheme, which presents certain similarities with Sraffa’s system. Cf. (Pasinetti1975).