We’ve all heard the phrase “equal pay for equal work.” Many of those who habitually repeat this mantra may not realize that it is simply a variation of the discredited labor theory of value (LTV), which is generally associated with Marxian economics. According to the LTV, the value of a product is related to the labor needed to produce it. The LTV prevailed in classical economics until the Marginal Revolution in the late 1800s. The marginalists proved that value is not the result of a product’s inputs, but the result of the subjective judgment of individuals.
~ Glenn Jacobs, "The Fallacy of Equal Pay for Equal Work," Freedom Daily, September 2, 2009