Do markets determine the unequal distribution of income under capitalism?* Well, yes and no.
The answer depends, of course, on the theory of income distribution one uses. Neoclassical economists focus exclusively on market exchanges and the idea that each factor of production (labor, capital, and land) receives a portion of total output in the form of income (wages, profits, or rent) according to its marginal contributions to production. In this sense, neoclassical economics represents a confirmation and celebration of capitalism’s “just deserts,” that is, everyone gets what they deserve.
Many other economists criticize this aspect of neoclassical theory and use an alternative approach. Stiglitz, for example, focuses on “rent-seeking” behavior—and therefore on the ways economic agents (such as those in the financial sector or CEOs) often rely on forms of power (political and/or economic) to secure more than their “just deserts.” Thus, for Stiglitz and others, the distribution of income is more unequal than it would be under perfect markets.
What about Marxian theory? It’s a bit different, in the sense that it relies on the assumptions similar to those of neoclassical theory while arriving at conclusions that are similar to those of the critics of the neoclassical theory of the distribution of income. The implication is that, even if and when markets are perfect (in the way neoclassical economists assume), the capitalist distribution of income violates the idea of “just deserts” (much in the way the critics argue).
Let me explain. Marx starts with the presumption that all markets operate much in the way the classical political economists then (and neoclassical economists today) presume. He then shows that even when all commodities exchange at their values and workers receive the value of their labor power (that is, no cheating), capitalists are able to appropriate a surplus-value (that is, there is exploitation). No special modifications of the presumption of perfect markets need to be made. As long as capitalists are able, after the exchange of money for the commodity labor power has taken place, to extract labor from labor power during the course of commodity production, there will be an extra value, a surplus-value, that capitalists are able to appropriate for doing nothing.
So, according to the Marxian theory of value, the distribution of income is determined partly by markets (workers receive the value of their labor power), partly outside of markets (capitalists appropriate surplus-value by extracting labor from labor power in production), and then partly once again in markets (the surplus-value is realized in the form of money if and when capitalists are able to sell the commodities that are produced).
But that’s only the first step. To make the analysis more concrete, Marx recognizes the fact that industrial capitalists don’t get to keep all the surplus-value they appropriate from their workers. They are forced to share their ill-gotten gains with others who help in various ways to secure the conditions of continued exploitation: other industrial capitalists (through competition within industries), financial capitalists (via an unequal exchange of money in the form of loans), the state (in the form of taxes), supervisors and managers (whose incomes represent distributions of the surplus-value), landlords (who are able to secure a portion of the surplus-value in the form of rent), and so on. The rest is kept as enterprise profits. Once again, then, the distribution of income is determined both inside and outside markets.
All of the preceding analysis is carried out under the assumption that all markets are perfect. Then, of course, at an even more concrete level, it is possible to introduce and explore the implications of all kinds of market imperfections, such as “political or economic power, rent-seeking, cronyism, imperfect information, monopolies,” which no doubt characterize contemporary capitalism.
The point is, the Marxian theory of the distribution of income identifies an unequal distribution of income that is endemic to capitalism—and thus a fundamental violation of the idea of “just deserts”—even if all markets operate according to the unrealistic assumptions of mainstream economists. And that intrinsically unequal distribution of income within capitalism (as determined both within and beyond markets) becomes even more unequal once we consider all the ways the mainstream assumptions about markets are violated on a daily basis within the kinds of capitalism we witness today.
Hence, my answer to the question, do markets determine the unequal distribution of income under capitalism? Well, yes (although not according to the neoclassical theory of marginal productivity) and no (since it is necessary to leave the sphere of exchange, the “very Eden of the innate rights of man,” and enter the realm of production in order to identify the existence of capitalist exploitation).
*This post is a response to Branko Milanovic’s summary of Joseph Stiglitz’s presentation at the recent American Economic Association/Allied Social Sciences meetings in Boston. According to Milanovic, Stiglitz divided theories of income distribution into two groups: market-based theories (such as neoclassical or marginal-productivity theory) and non-market theories (according to which incomes are “determined largely by exploitation, political or economic power, rent-seeking, cronyism, imperfect information, monopolies”).