Keywords: History of Ideas, Methodology & Philosophy;
 

In his blog of 26 March 2009, Paul Krugman pointed out that Anton Kaletsky was wrong when he claimed that John Maynard Keynes did not have an economic model when he wrote his General Theory. (Kaletsky is not always right when he criticises economists he disagrees with.) I wrote the following note which places Keynes in an intellectual context.
 

The famous economist, Alfred Marshall, Keynes’ mentor and probably a better mathematician, famously wrote,
 

[I had] a growing feeling in the later years of my work at the subject that a good mathematical theorem dealing with economic hypotheses was very unlikely to be good economics: and I went more and more on the rules – (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.
 

Paul Krugman is also a disciple of Marshall. Would that there were more economists who were.