The Theory of Subjective Valuation Was Defended Against the New System Based on Labor Costs by Condillac Who Said “Costs Are Not the Cause of Value; Rather, Value Is the Cause of Costs”

With Galiani and Turgot subjective valuation becomes the keystone for a system of thinking. This theory had to be defended against the new classical system which was based on labor costs. The defense of Galiani, his followers, and his friends was taken over by Condillac. According to him, costs are not the cause of value; rather, value is the cause of costs. Condillac's counter-attack against the classical cost theory is the parting shot of an army falling back. Before 1800 Italian and French writers were already drawn into the orbit of British classical thinking. An attempted synthesis of utility value and cost theory was the main object of later Italian writers.

--Emil Kauder, A History of Marginal Utility Theory (Princeton, NJ: Princeton University Press, 1965), 27.