Magazine article Ideas on Liberty

The Law of Supply and Demand

Magazine article Ideas on Liberty

The Law of Supply and Demand

Article excerpt

The theory of supply and demand is recognized almost universally as the first step toward understanding how market prices are determined and the way in which these prices help shape production and consumption decisions-the decisions that make up not only the skeleton, but also the flesh and blood of the economic system. Austrian economics thoroughly agrees with this. However, when we dig just a little below the surface of the "law" of supply and demand, we encounter difficulties that have, directly or indirectly, led Austrians to explain the determination of prices differently from how it is often, at least implicitly, presented. I will try to explain the sense in which Austrians are unhappy with the textbook presentations of supply and demand-and are yet fully in agreement with the general emphasis on supply and demand as being the key to economic understanding.

The Basic Proposition

The basic insight underlying the law of supply and demand is that at any given moment a price that is "too high" will leave disappointed would-be sellers with unsold goods, while a price that is "too low" will leave disappointed would-be buyers without the goods they wish to buy. There exists a "right" price, at which all those who wish to buy can find sellers willing to sell and all those who wish to sell can find buyers willing to buy. This "right" price is therefore often called the "market-clearing price."

Supply-and-demand theory revolves around the proposition that a free, competitive market does in fact successfully generate a powerful tendency toward the market-clearing price. This proposition is often seen as the most important implication of (and premise for) Adam Smith's famed invisible hand. Without any conscious managing control, a market spontaneously generates a tendency toward the dovetailing of independently made decisions of buyers and sellers to ensure that each of their decisions fits with the decisions made by the other market participants. Were this tendency to be carried to the limit, no buyer (seller) would be misled so as to waste time attempting to buy (sell) at a price below (above) the market-clearing price. No buyer (seller) would in fact pay (receive) a price higher (lower) than necessary to elicit the agreement of his trading partner. To the extent that this proposition is valid, free competitive markets achieve what F. A. Hayek has justifiably called a "marvel." But it is in regard to the validity of this proposition (and in particular to our reasons for being convinced that this proposition is both valid and relevant) that Austrians differ sharply with mainstream textbook economics. And it is precisely because of the universally acknowledged centrality of the supply-and-demand proposition for all of economics that this disagreement is so important.

The Role of Knowledge

The mainstream textbook approach to this proposition is, in one way or another, explicitly or implicitly, based on the assumption of perfect knowledge. The Austrian approach does not make the perfect-knowledge assumption the foundation for this proposition; quite the contrary, Austrians base the proposition squarely on the insight that its validity proceeds from market processes set in motion by the inevitable imperfections in knowledge, which characterize human interaction in society.

In certain respects the mainstream view is not unreasonable. In many contexts we generally take it for granted that human beings are aware of the opportunities available to them. When economists believe, for example, that a price increase will cut the quantity people seek to purchase, and a price decrease will stimulate sales, this belief is based on the reasonable assumption that such price increases or decreases are in fact likely to become known to prospective buyers soon enough to make a difference.

The mainstream view takes this not unreasonable assumption and pursues it relentlessly, in effect, to its logical-but no longer quite so reasonable-conclusion. …

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