By Murray Rothbard
Essentially Say's law is a stern and proper response to the various economic ignoramuses as well as self-seekers who, in every economic recession or crisis, begin to complain loudly about the terrible problem of general "overproduction" or, in the common language of Say's day, a "general glut" of goods on the market. "Overproduction" means production in excess of consumption: that is, production is too great in general compared to consumption, and hence products cannot be sold in the market. If production is too large in relation to consumption, then obviously this is a problem of what is now called "market failure," a failure which must be compensated by the intervention of government.[...]
Say understandably reacted in horror to this analysis and to the prescription. In the first place, he pointed out, the wants of man are unlimited, and will continue to be until we achieve genuine general superabundance — a world marked by the prices of all goods and services falling to zero. But at that point there would be no problem of finding consumer demand, or, indeed, any economic problem at all. There would be no need to produce, to work, or to worry about accumulating capital, and we would all be in the Garden of Eden.[..]
Since, apart from the Garden of Eden, production always falls short of man's wants, this means that there is no need to worry about any lack of consumption. The problem that limits wealth and living standards is a deficiency of production. On the market, Say points out, producers exchange their products for money and they use the money to buy the products of others. That is the essence of the exchange, or market, economy. Therefore the supply of one good constitutes, at bottom, the demand for other goods. Consumption demand is simply the embodiment of the supply of other products, whose owners are seeking to purchase the products in question. Far better to have demand emerging from the supply of other products, as on the free market, than for the government to stimulate consumer demand without any corresponding production.
For the government to stimulate consumption by itself "is no benefit to commerce; for the difficulty lies in supplying the means, not in stimulating the desire for consumption; and we have seen that production alone, furnishes the mean[...]
Those who complain about overproduction or underconsumption rarely talk in terms of price, yet these concepts are virtually meaningless if the price system is not always held in mind. The question should always be: production or sales at what price! Demand or consumption at what price! There is never any genuine unsold surplus, or "glut," whether specific or general over the whole economy, if prices are free to fall to clear the market and eliminate the surplus.
The above originally appeared at Mises.org.