The behavior of the economy as a whole, at the aggregate, macro-level, is built up from the individual equations at the micro-level.

Keynes tried to show that market economies could settle in equilibrium states in which the labour market did not clear, and in which the level of unemployment was high. He believed that this was due to a particular example of market failure, developed in his concept of effective demand.

Despite the high salaries involved, employing economists is a cost-effective way for banks, and stockbrokers to secure exposure in the media.

The temptation to use mathematics is irresistible for economists. It appears to convey the appropriate air of scientific authority and precision to economists' musings.

Books proliferate, and occasionally sell in very large numbers, which claim to have found the rule, or small set of rules, which will guarantee business success. But business is far too complicated, far too difficult an activity to distil into a few simple commands ... It is failure rather than success which is the distinguishing feature of corporate life.

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.

By any reasonable criteria, the discipline of economics as a whole, in its present state, is sadly lacking.