The Free Market is a summary term for an array of exchanges that take place in society. Each exchange is undertaken as a voluntary agreement between two people or between groups of people represented by agents. These two individuals (or agents) exchange two economic goods, either tangible commodities or nontangible services. Thus, when I buy a newspaper from a news dealer for fifty cents, the news dealer and I exchange two commodities: I give up fifty cents, and the news dealer gives up the newspaper. Or if I work for a corporation, I exchange my labor services, in a mutually agreed way, for a monetary salary; here the corporation is represented by a manager (an agent) with the authority to hire.

Both parties undertake the exchange because each expects to gain from it. Also, each will repeat the exchange next time (or refuse to) because his expectation has proved correct (or incorrect) in the recent past. Trade, or exchange, is engaged in precisely because both parties benefit; if they did not expect to gain, they would not agree to the exchange.

This simple reasoning refutes the argument against free trade typical of the "mercantilist" period of sixteenth- to eighteenth-century Europe, and classically expounded by the famed sixteenth-century French essayist Montaigne. The mercantilists argued that in any trade, one party can benefit only at the expense of the other, that in every transaction there is a winner and a loser, an "exploiter" and an "exploited." We can immediately see the fallacy in this still-popular viewpoint: the willingness and even eagerness to trade means that both parties benefit. In modern game-theory jargon, trade is a win-win situation, a "positive-sum" rather than a "zero-sum" or "negative-sum" game.

How can both parties benefit from an exchange? Each one values the two goods or services differently, and these differences set the scene for an exchange. I, for example, am walking along with money in my pocket but no newspaper; the news dealer, on the other hand, has plenty of newspapers but is anxious to acquire money. And so, finding each other, we strike a deal.

Two factors determine the terms of any agreement: how much each participant values each good in question, and each participant's bargaining skills. How many cents will exchange for one newspaper, or how many Mickey Mantle baseball cards will swap for a Babe Ruth, depends on all the participants in the newspaper market or the baseball card market — on how much each one values the cards as compared to the other goods he could buy. These terms of exchange, called "prices" (of newspapers in terms of money, or of Babe Ruth cards in terms of Mickey Mantles), are ultimately determined by how many newspapers, or baseball cards, are available on the market in relation to how favorably buyers evaluate these goods. In shorthand, by the interaction of their supply with the demand for them.

Given the supply of a good, an increase in its value in the minds of the buyers will raise the demand for the good, more money will be bid for it, and its price will rise. The reverse occurs if the value, and therefore the demand, for the good falls. On the other hand, given the buyers' evaluation, or demand, for a good, if the supply increases, each unit of supply — each baseball card or loaf of bread — will fall in value, and therefore, the price of the good will fall. The reverse occurs if the supply of the good decreases.

The market, then, is not simply an array, but a highly complex, interacting latticework of exchanges. In primitive societies, exchanges are all barter or direct exchange. Two people trade two directly useful goods, such as horses for cows or Mickey Mantles for Babe Ruths. But as a society develops, a step-by-step process of mutual benefit creates a situation in which one or two broadly useful and valuable commodities are chosen on the market as a medium of indirect exchange. This money-commodity, generally but not always gold or silver, is then demanded not only for its own sake, but even more to facilitate a re-exchange for another desired commodity. It is much easier to pay steelworkers not in steel bars, but in money, with which the workers can then buy whatever they desire. They are willing to accept money because they know from experience and insight that everyone else in the society will also accept that money in payment.

The modern, almost infinite latticework of exchanges, the market, is made possible by the use of money. Each person engages in specialization, or a division of labor, producing what he or she is best at. Production begins with natural resources, and then various forms of machines and capital goods, until finally, goods are sold to the consumer. At each stage of production from natural resource to consumer good, money is voluntarily exchanged for capital goods, labor services, and land resources. At each step of the way, terms of exchanges, or prices, are determined by the voluntary interactions of suppliers and demanders. This market is "free" because choices, at each step, are made freely and voluntarily.

The free market and the free price system make goods from around the world available to consumers. The free market also gives the largest possible scope to entrepreneurs, who risk capital to allocate resources so as to satisfy the future desires of the mass of consumers as efficiently as possible. Saving and investment can then develop capital goods and increase the productivity and wages of workers, thereby increasing their standard of living. The free competitive market also rewards and stimulates technological innovation that allows the innovator to get a head start in satisfying consumer wants in new and creative ways.

Not only is investment encouraged, but perhaps more important, the price system, and the profit-and-loss incentives of the market, guide capital investment and production into the proper paths. The intricate latticework can mesh and "clear" all markets so that there are no sudden, unforeseen, and inexplicable shortages and surpluses anywhere in the production system.

But exchanges are not necessarily free. Many are coerced. If a robber threatens you with "Your money or your life," your payment to him is coerced and not voluntary, and he benefits at your expense. It is robbery, not free markets, that actually follows the mercantilist model: the robber benefits at the expense of the coerced. Exploitation occurs not in the free market, but where the coercer exploits his victim. In the long run, coercion is a negative-sum game that leads to reduced production, saving, and investment, a depleted stock of capital, and reduced productivity and living standards for all, perhaps even for the coercers themselves.

Government, in every society, is the only lawful system of coercion. Taxation is a coerced exchange, and the heavier the burden of taxation on production, the more likely it is that economic growth will falter and decline. Other forms of government coercion (e.g., price controls or restrictions that prevent new competitors from entering a market) hamper and cripple market exchanges, while others (prohibitions on deceptive practices, enforcement of contracts) can facilitate voluntary exchanges.