By the later nineteenth century, the very general principle of objective fairness had become central to the understanding, both on the left and on the right, of what it is that makes an economic exchange morally acceptable.5 Clearly however, convergence on the ideal that work should receive objectively fair compensation did not mean that there was consensus on a particular definition of fair wages. On the contrary, the inherent vagueness of the notion of a fair wage resulted in a proliferation of diferent interpretations of the idea. The dificulty and vagueness of the idea of fair exchange of labor for a wage was a consequence of the problem of commensuration.
If fairness is an objective fact about an exchange, determined by the ratio obtaining between the exchanged substances, then those substances must be commensurable. That is, there must be some nonarbitrary procedure for translating the quantity of goods or services flowing in one direction into the quantity of goods and services flowing in the other. If the substances being exchanged are not commensurable, then clearly it would not be possible to “objectively” judge whether that exchange is a fair one. In order for fair exchange to be possible there must, therefore, be some metric by virtue of which the exchanged substances can be seen as standing in some definite quantitative relationship to one another. Moreover, if an exchange is to be objectively fair, rather than just fair according to convention, the metric must measure some essential quality the exchanged substances have in common.6 The notion of an objectively fair exchange, as opposed to an exchange that is fair according to convention, thus involves the presupposition that the substances being exchanged share qualities such that they are commensurable.7
A Theory of Mass Consumption as Wage-Labor Commensuration
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