This conception of productive labour as being that labour which produces a surplus value is also found in the theories of the Physiocrats, and the Mercantilists. The Physiocrats correctly analysed the source of surplus value as arising in production, as the workers produced a greater quantity of use values than was required for their own reproduction.
It was this surplus of use values, a surplus product, that constituted the surplus value, which was appropriated by the landlord, as owner of the force of Nature – the fertility of the land – which the Physiocrats saw as the basis of this productivity of labour. On that basis, it was only this agricultural labour that was productive, because it was only this agricultural labour which created the surplus product, which in turn could be expended by the landlords to buy industrial commodities, and thereby lead to an expansion in production in general.
The Mercantilists believed that surplus value arose from foreign trade, such that a surplus arose whereby the value of commodities exported was greater than the value of the commodities imported, which were required for the production of those exports. On this basis, only that labour employed in the production of these commodities to be exported was productive.
The basis of this view of the Mercantilists was that they saw that in those economies like the Netherlands, and then Britain, which were able to export more than they imported, they were able to amass increasing stores of gold and silver, which they equated with wealth.
“They saw that in these countries there was a rapid growth of wealth and of the middle class.” (p 154)
The mechanism by which gold had this effect they saw as follows. When more gold flowed into the economy, it caused the prices of commodities to rise, but wages did not rise so fast. This meant that surplus-value rose.
“Secondly as only exported goods were measured in gold and silver on the basis of its reduced value, while those for home consumption continued to be measured in gold and silver according to its former value (until competition among the capitalists put an end to this measuring by two different standards), labour in the former branches of production appeared to be directly productive, that is, creating surplus-value, through the depression of wages below their former level.” (p 155)