The key insight of Adam Smith's Wealth of Nations is misleadingly simple: if an exchange between two parties is voluntary, it will not take place unless both believe they will benefit from it. Most economic fallacies derive from the neglect of this simple insight, from the tendency to assume that there is a fixed pie, that one party can gain only at the expense of another.

Adam Smith is, of course, justly lauded for his advocacy of free markets and limited government. Particularly famous is his idea that each person’s pursuit of self-interest leads, as if by an invisible hand, to socially efficient outcomes.

[Adam Smith was] a higher above all genius (...) who had recognized some mistakes of the mercantile and physiocrats systems, put new principles of a theory called the industrial system, and directed minds for this road, on which they should necessarily advance

But Adam Smith was a philosopher as well as well as an economist, famous in his time as much for his Theory of Moral Sentiments as for The Wealth of Nations. And as he understood so well, society is more than the sum of its individual parts.

Adam Smith saw what had happened to markets and societies for millennia. Winners are never satisfied with success in the latest market battle, with a cool product or financial or political achievement. As humans, we use any recent advantage to ensure that competitors will fail in future struggles.

Although Adam Smith is today often regarded as a “conservative” figure, he in fact attacked some of the dominant ideas and interests of his own times. Moreover, the idea of a spontaneously self-equilibrating system — the market economy — first developed by the Physiocrats and later made part of the tradition of classical economics by Adam Smith, represented a radically new departure, not only in analysis of social causation but also in seeing a reduced role for political, intellectual, or other elites as guides or controllers of the masses.

The most important single central fact about a free market is that no exchange takes place unless both parties benefit.

Economists have uncovered the conditions necessary if Adam Smith’s results are to be achieved and where, in the real world, such conditions do not appear to be found, they have proposed changes which are designed to bring them about. It is what one finds in the textbooks. Harold Demsetz has said rightly that what this theory analyses is a system of extreme decentralisation. It has been a great intellectual achievement and it throws light on many aspects of the economic system. But it has not been by any means all gain.

By virtue of exchange, one man's prosperity is beneficial to all others.

Voluntary exchanges are by definition advantageous to their participants. Within this voluntary, mutually beneficial relationship, I give up an item I value less, for something I value more: a fee for the desired product or service. My trading partners, whose valuations are in complementary opposition to mine, reciprocate in kind. Ceteris paribus (all other things being equal), there's nothing wrong with my running a trade deficit with Costco, my hair stylist or my GTI dealer, as I do—just as long as I pay for my purchases. However, the data demonstrate that Americans, in general, are not paying for their purchases.

People forget the fundamental distinction between Adam Smith's version of The Invisible Hand and what I suppose you could regard as Bastiat's version. The French idea was that there is somehow a harmony in nature so that by natural forces if people were left free to pursue their own interests they would benefit everybody. Adam Smith's was a much more subtle and sophisticated argument, that it is possible to set up institutions under which people pursuing their own interests will benefit everybody. His invisible hand required the right set of institutions and I think that's the case. After all, the distinction between a collectivist society and a market or individualist society is not whether people pursue their own interests. If I take Russia, for example, the people in Russia are all pursuing their own interests but the institutions set up in Russia make what is in each person's own interest different from what it would be in the United States or in Britain.

If I were five-and-twenty or thirty, instead of, unhappily, twice that number of years, I would take Adam Smith in hand—I would not go beyond him, I would have no politics in it—I would take Adam Smith in hand, and I would have a League for free trade in Land just as we had a League for free trade in Corn. You will find just the same authority in Adam Smith for the one as for the other; and if it were only taken up as it must be taken up to succeed, not as a political, revolutionary, Radical, Chartist notion, but taken up on politico-economic grounds, the agitation would be certain to succeed; and if you apply free trade in land and to labour too—that is, by getting rid of those abominable restrictions in your parish settlements, and the like—then, I say, the men who do that will have done for England probably more than we have been able to do by making free trade in corn.

Specialisation, accompanied by exchange, is the source of economic prosperity. Here, in my own words, is what a modern version of Smithism claims. First, the spontaneous and voluntary exchange of goods and services leads to a division of labour in which people specialise in what they are good at doing. Second, this in turn leads to gains from trade for each party to a transaction, because everybody is doing what he is most productive at and has the chance to learn, practise and even mechanise his chosen task. Individuals can thus use and improve their own tacit and local knowledge in a way that no expert or ruler could. Third, gains from trade encourage more specialisation, which encourages more trade, in a virtuous circle. The greater the specialisation among producers, the greater is the diversification of consumption: in moving away from self-sufficiency people get to produce fewer things, but to consume more. Fourth, specialisation inevitably incentivises innovation, which is also a collaborative process driven by the exchange and combination of ideas. Indeed, most innovation comes about through the recombination of existing ideas for how to make or organise things. The more people trade and the more they divide labour, the more they are working for each other. The more they work for each other, the higher their living standards. The consequence of the division of labour is an immense web of cooperation among strangers: it turns potential enemies into honorary friends. A woollen coat, worn by a day labourer, was (said Smith) ‘the produce of a great multitude of workmen. The shepherd, the sorter of the wool, the wool-comber or carder, the dyer, the scribbler, the spinner, the weaver, the fuller, the dresser . . .’ In parting with money to buy a coat, the labourer was not reducing his wealth. Gains from trade are mutual; if they were not, people would not voluntarily engage in trade. The more open and free the market, the less opportunity there is for exploitation

We should not forget Adam Smith’s perspicuous observation that the “masters of mankind” — in his day, the merchants and manufacturers of England — never cease to pursue their “vile maxim”: “All for ourselves, and nothing for other people.