Happy Birthday, Alfred
The great British economist Alfred Marshall “turns” 170 years old today. Here is a link to his Principles of Economics, which was one of the most influential books in the history of the discipline. Here is Keynes’ remembrance of Marshall.
From Marshall’s Principles on the “Substance of Economics”:
The advantage which economics has over other branches of social science appears then to arise from the fact that its special field of work gives rather larger opportunities for exact methods than any other branch. It concerns itself chiefly with those desires, aspirations and other affections of human nature, the outward manifestations of which appear as incentives to action in such a form that the force or quantity of the incentives can be estimated and measured with some approach to accuracy; and which therefore are in some degree amenable to treatment by scientific machinery. An opening is made for the methods and the tests of science as soon as the force of a person’s motives—not the motives themselves—can be approximately measured by the sum of money, which he will just give up in order to secure a desired satisfaction; or again by the sum which is just required to induce him to undergo a certain fatigue.
And here he is on mathematics as used in economics (he wrote this in 1906) – we would be better off as a discipline if we followed Marshall’s rules a bit more closely:
(1) Use mathematics as a shorthand language, rather than an engine of inquiry. (2) Keep to them till you have done. (3) Translate into English. (4) Then illustrate by examples that are important in real life. (5) Burn the mathematics. (6) If you can’t succeed in (4), burn (3). This last I did often.