One interesting footnote: although Friedman made great strides in macroeconomics by applying the concept of individual rationality, he also knew wher… - Paul Krugman

The world is full of self-organizing systems, systems that form structures not merely in response to inputs from outside but also, indeed primarily, in response to their own internal logic. Global weather is a self-organizing system; so, surely, is the global economy.

No, the problem that the politicians have with the professors is not one of failure to communicate; it is one of failure to say what politicians want (need) to hear, especially when they are trying to seize power from other politicians. And necessity is the mother of invention: a different group, the policy entrepreneurs, has arisen to fill the gap.

In this part of the lecture I have argued that a number of works in development economics written during the 1950s contained, more or less explicitly and more or less self-consciously, a theory in which strategic complementarity played a key role in development: external economies arose from a circular relationship in which the decision to invest in large-scale production depended on the size of the market, and the size of the market depended on the decision to invest. Whatever the practical relevance of this theory, it made perfectly good logical sense. Yet this was subsequently abandoned, to such an extent that classic papers in the field began to seem, as the physicist Wolfgang Pauli used to say, "not even wrong" — simply incomprehensible.