ABSTRACT
As early as the 1760s, a keen confrontation began between followers and critics of physiocracy, including the question of unproductive labour. William Spence was a follower of the physiocrats, but–contrary to John Gray–he took physiocracy as a basis to defend landed interests. His approach was highly orthodox: agriculture is the only productive sector and manufacture, like commerce, is mere exchange of equivalents. Non-agricultural activities can yield a profit, because of the increase in the price of their products; but they cannot generate a surplus, because they only transform the products generated in agriculture. Condillac is not really concerned with surplus or exchange value, but with utility. Although artisans do not add new value to the product, they add wealth because the latter depends on utility. David Buchanan severely criticised the physiocrats. Given their idea that the net surplus in agriculture is granted by high prices, surplus goes to the detriment of consumers, who would benefit from lower prices.
