Ludwig von Mises, Human Action (1949):
“Each party attaches a higher value to the good he receives than to that he gives away. The exchange ratio, the price, is not the product of an equality of valuation, but, on the contrary, the product of a discrepancy in valuation.”
Destutt de Tracy, A Treatise On Political Economy (1817):
“(A)n exchange is a transaction in which the two contracting parties both gain. Whenever I make an exchange freely, and without constraint, it is because I desire the thing I receive more than that I give; and, on the contrary, he with whom I bargain desires what I offer more than that which he renders me. When I give my labour for wages it is because I esteem the wages more than what I should have been able to produce by labouring for myself; and he who pays me prizes more the services I render him than what he gives me in return.”
Murray N. Rothbard, An Austrian Perspective on the History of Economic Thought (1995):
“Another grave fallacy in the same paragraph in the Ethics did incalculable damage to future centuries of economic thought. There Aristotle says that in order for an exchange (any exchange? a just exchange?) to take place, the diverse goods and services "must be equated," a phrase Aristotle emphasizes several times. It is this necessary "equation" that led Aristotle to bring in the mathematics and the equal signs. His reasoning was that for A and B to exchange two products, the value of both products must be equal, otherwise an exchange would not take place. The diverse goods being exchanged for one another must be made equal because only things of equal value will be traded.
The Aristotelian concept of equal value in exchange is just plain wrong, as the Austrian School was to point out in the late nineteenth century. If A trades shoes for sacks of wheat owned by B, A does so because he prefers the wheat to the shoes, while B's preferences are precisely the opposite. If an exchange takes place, this implies not an equality of values, but rather a reverse inequality of values in the two parties making the exchange. If I buy a newspaper for 30¢ I do so because I prefer the acquisition of the newspaper to keeping the 30 cents, whereas the newsagent prefers getting the money to keeping the newspaper. This double inequality of subjective valuations sets the necessary precondition for any exchange.”
Murray N. Rothbard, Toward a Reconstruction of Utility and Welfare Economics (1956):
“Let us now consider exchanges on the free market. Such an exchange is voluntarily undertaken by both parties. Therefore, the very fact that an exchange takes place demonstrates that both parties benefit (or more strictly, expect to benefit) from the exchange. The fact that both parties chose the exchange demonstrates that they both benefit. The free market is the name for the array of all the voluntary exchanges that take place in the world. Since every exchange demonstrates a unanimity of benefit for both parties concerned, we must conclude that the free market benefits all its participants.”
Murray N. Rothbard, Man, Economy, and State (1962):
“On the one hand, when the society is free and there is no intervention, everyone will always act in the way that he believes will maximize his utility, i.e., will raise him to the highest possible position on his value scale. In short, everyone's utility ex ante will be “maximized” (provided we take care not to interpret “utility” in a cardinal manner). Any exchange on the free market, indeed any action in the free society, occurs because it is expected to benefit each party concerned. If we may use the term “society” to depict the pattern, the array, of all individual exchanges, then we may say that the free market maximizes social utility, since everyone gains in utility from his free actions.3
Coercive intervention, on the other hand, signifies per se that the individual or individuals coerced would not have voluntarily done what they are now being forced to do by the intervener. The person who is coerced into saying or not saying something or into making or not making an exchange with the intervener or with a third party is having his actions changed by a threat of violence. The man being coerced, therefore, always loses in utility as a result of the intervention, for his action has been forcibly changed by its impact.”