Engels cites Duhring's “fundamental laws” of economics.
“Law No. 1. “The productivity of economic instruments, natural resources and human energy is increased by inventions and discoveries.”” (p 283)
Unlike Marx, who locates the role of productivity and technological innovation as stemming from an actual Natural Law – The Law of Value – Duhring's Law No.1 is banal. For Marx, The Law of Value acts as the motor of historical evolution, in the same way that The Law of Natural Selection is the motor of biological evolution. The Law of Value means that society must always seek to reduce unit values, in order to increase its production of use-values/real wealth. To do that, it must raise social productivity, a large part of which is technological innovation.
As Marx describes, for example, in The Poverty of Philosophy, it is this technological innovation which, then, results in the development of new productive relations, and these new productive relations create new forms of property, new social classes as the personification of this property, and so new social relations – a social revolution.
But, Duhring has no such material, historical basis for his law. He has no such means of setting out why societies seek to raise productivity at all. Why do they bother, rather than just continuing as they are? Moreover, as Engels notes, not all technological innovations do raise productivity. Engels points to the masses of paper in patent offices of things that were never taken up. Heath Robinson was renowned for his contraptions, none of which had practical application. Again, here, it is The Law of Value that is determinant, because it is only those innovations that actually do reduce unit values that pass the test of natural selection.
And, here, too, as Marx and Engels set out, in Capital III, it is the historically specific nature of capitalist production that determines the form in which that is manifest. Under capitalism, it is not enough simply that a new machine reduces the unit value of commodities, it must reduce those values – labour-time required for production- by such an amount that it is greater than the savings in wages that it brings about.
The importance of this can be seen from the previous discussion. In other words, the value of commodities (setting aside the constant capital) is not only equal to wages, but wages plus the surplus value. Again, here is the distinction between the social cost of production (value) of the commodities, as against the private cost of production (wages) to the capitalist. It is why, as Marx sets out in Capital and Connolly set out in relation to the cooperative at Ralahine, workers' cooperatives always have an incentive to be early adopters of such technologies, because, for the workers, the social cost of production is the same as their private cost of production, i.e. the labour they must expend.
For the individual capitalist firm, the only point of introducing a new machine is to reduce its individual costs of production, and so increase its profit. So, the machine must cost less than the wages saved. But, for the workers, the point of a new machine is only that it lightens the burden of their labour, enables them to produce more whilst working less.
“If “the triumph of the higher scientific method” in economics, as in philosophy, consists only in giving a high-sounding name to the first commonplace that comes to one’s mind, and trumpeting it forth as a natural law or even a fundamental law, then it becomes possible for anybody, even the editors of the Berlin Volkszeitung, to lay “deeper foundations” and to revolutionise science.” (p 283-4)