However, as should be clear from the foregoing, there are two distinct Ricardian 
Problems, only one of which is addressed by Sraffa in his celebrated book: he is 
exclusively concerned with the theoretical measure, or, to use his above phrasing, 
’the law of value’. The Standard commodity proves to be a powerful tool in the theory 
of value and distribution of classical derivation; it simplifies the analysis of the 
mathematical properties of the System of normal competitive prices. It deserves 
mentioning that the results derived by Sraffa can also be obtained by using the 
Perron-Frobenius theorem. In fact, Sraffa’s demonstration of the existence and 
uniqueness of the Standard commodity (in the case of single production) can be 
regarded as a (not fully complete) proof of this theorem. For a more detailed 
exposition of this view, see Kurz and Salvadori (1987). 
If this interpretation is accepted then there would seem to be no room for attributing to 
the Standard commodity the entirely different role of providing a measure which can 
be used in intertemporal or interspatial comparisons. In fact, as Steindl points out, 
different techniques, either of the same economy at different times or of different 
economies at the same time, generally have different Standard Commodities. Which of 
the Standard Commodities should then be adopted as the common Standard, and 
why? To take an extreme case, imagine that two Systems of production have no 
single commodity in common. In this case it is all too obvious that the idea under 
consideration is bound to founder. 
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So far it has been assumed that a Standard commodity always exists and that it is 
unique. However, this need not be the case. In particular, it is well known that for 
Systems with some jointness of production (including the case of intensive diminishing 
returns on homogenous land, fixed Capital and joint production proper) a Standard 
commodity may or may not exist (cf. again Kurz and Salvadori, 1987, pp. 878-879). 
Since joint production is to be considered the general case, and is empirically very 
common indeed (see Steedman, 1984), it cannot be presumed that a Standard 
commodity always exists. 
After these more general remarks on the role of the Standard commodity in Sraffa’s 
analysis I shall, in what follows, comment on some particular aspects of Professor 
Steindl's investigation. 
Scrutiny shows that in the discussion of what he calls ’the main issue’ of his paper 
(commencing with section 6), Professor Steindl is in fact pre-eminently concerned 
with comparisons of different economic Systems in terms of their maximum growth