The argument put forward is that if we have c 100 + v 50 + s 50 = 200, but there is a change in values, the current reproduction cost theory, used by Marx might result in negative new value. So, if the value of wage goods rises, so that v becomes 110, due, say to a severe crop failure, the surplus value would become -10. However, this is not a negative new value, as the neo-Ricardians claim. It is only a negative surplus-value (loss), resulting from the fact that the value of labour-power has risen to a level greater than the amount of new value created by labour. To deny the possibility of such a situation in some individual, specific case, would be to deny the possibility of any firm making losses!
Roberts sets out the basis of this confusion when he, later, confuses labour that is productive of new value, with productive labour, i.e. productive of surplus value/capital, and exchanges with capital. Again, I will deal with that later.
Labour-power is a use-value, and, because it is, also, the product of labour, i.e. the labour required to reproduce it, in the form of food, clothes, shelter, education, health and social care etc., it is, in every mode of production, also, a product, and so has value. By contrast, labour has no value, as Marx and Engels repeatedly stated.
"Labour is the measure of all values, but labour itself has no value."
This value of labour-power has no relation to the value that the given labourer produces by the act of labour. Indeed, were that not the case, it would never have been possible for mankind to have progressed from the most basic level of existence. It requires that the labourer can produce more in a day than is required to reproduce their labour-power for that day.
But, in Roberts' account, as with that of Proudhon and Duhring, it is not labour that creates value, but labour-power. In capitalist economies, the value of that labour-power, takes the phenomenal form of wages. Consequently, we arrive at the conclusion, on Roberts' basis, as with the argument of Proudhon and Duhring, that value is determined by wages! The consequence of that is that we, then, arrive at the conclusion, also of Proudhon and Duhring that wage rises cause price rises.
Roberts has, of course, recoiled from such a conclusion, in trying to explain inflation, but only by simply putting forward the mirror image of that conclusion, by explaining inflation, instead by rising profits, monopoly profits, and so on, which I have dealt with previously. Not surprisingly, Duhring also, made similar arguments about the role of monopoly and force in explaining the existence of profits, and price rises. I will deal with that later.
Marx and Engels note, in Anti-Duhring,
“The determination of the value of commodities by wages, which in Adam Smith still frequently appeared side by side with its determination by labour-time, has been banned from scientific political economy since Ricardo, and nowadays survives only in vulgar economics...
After all, it is clear that what a labourer produces and what he costs are just as much different things as what a machine produces and what it costs. The value created by a labourer in a twelve-hour working-day has nothing in common with the value of the means of subsistence which he consumes in this working-day and the period of rest that goes with it. In these means of subsistence there may be embodied three, four or seven hours of labour-time varying with the stage of development reached in the productivity of labour. If we assume that seven hours of labour were necessary for their production, then the theory of value of vulgar economics which Herr Dühring has accepted implies that the product of twelve hours of labour has the value of the product of seven hours of labour, that twelve hours of labour are equal to seven hours of labour, or that 12=7. To put it even more plainly: A labourer working on the land, no matter under what social relationships produces in a year a certain quantity of grain, say sixty bushels of wheat. During this time he consumes a sum of values amounting of forty-five bushels of wheat. Then the sixty bushels of wheat have the same value as the forty-five bushels, and that in the same market and with other conditions remaining absolutely identical; in other words, sixty=forty-five. And this styles itself political economy!
The whole development of human society beyond the stage of brute savagery begins on the day when the labour of the family created more products than were necessary for its maintenance on the day when a portion of labour could be devoted to the production no longer of the mere means of subsistence, but of means of production. A surplus of the product of labour over and above the costs of maintenance of the labour, and the formation and enlargement, out of this surplus, of a social production and reserve fund, was and is the basis of all social, political and intellectual progress.”