The Keynesian approach advances a critique of claims for market selfregulation common among classical and neoclassical thinkers. The Keynesian critique questions the claim that an unregulated market system will fully exploit society's productive potential.

At its core, the argument for market self-regulation contends that the market system will bring together wants and means in such a way as to satisfy those wants so far as is possible given the means available. This is a claim about prices and demand. The prices of goods will adjust so as to assure the market will clear; what producers bring to the market will find buyers. The price mechanism assures adequate demand. It also directs capital investment into those lines, indicated by higher profitability, where more is needed.

In this argument, individual producers may fail to sell all they produce, or can produce, because what they have to sell is not wanted by those with the purchasing power to buy it. They have miscalculated in their decisions regarding the line of investment for their capital and produced the wrong goods. The low profit and income of these producers is the fate that befalls those who do not provide what consumers want. This can happen to the individual, but not to the aggregate of sellers.

The Keynesian critique argues that failure to find buyers can be a systemic problem having nothing to do with a bad fit between what has been produced and what is needed.