One solution offered to the paradox of the value is through the theory of marginal utility proposed by
Carl Menger, one of the founders of the
Austrian School of economics. As William Barber put it, human volition, the human subject, was "brought to the centre of the stage" by
marginalist economics, as a bargaining tool. Neoclassical economists sought to clarify choices open to producers and consumers in market situations, and thus "fears that cleavages in the economic structure might be unbridgeable could be suppressed". Without denying the applicability of the Austrian theory of value as
subjective only, within certain contexts of price behavior, the Polish economist
Oskar Lange felt it was necessary to attempt a serious
integration of the insights of classical political economy with neo-classical economics. This would then result in a much more realistic theory of price and of real behavior in response to prices. Marginalist theory lacked anything like a theory of the social framework of real market functioning, and criticism sparked off by the
capital controversy initiated by
Piero Sraffa revealed that most of the foundational tenets of the marginalist theory of value either reduced to
tautologies, or that the theory was true only if counter-factual conditions applied. One insight often ignored in the debates about price theory is something that businessmen are keenly aware of: in different markets, prices may not function according to the same principles except in some very abstract (and therefore not very useful) sense. From the classical political economists to
Michał Kalecki it was known that prices for industrial goods behaved differently from prices for agricultural goods, but this idea could be extended further to other broad classes of goods and services. ==Price as productive human labour time==