In the recently recovered Preface to the French edition of The General Theory of Employment, Interest and Money Keynes refers to Montesquieu (1689–1755) as the greatest French economist. Addressing the French public Keynes writes that “Montesquieu was the real French equivalent of Adam Smith. The greatest of your economists, head and shoulders above the physiocrats in penetration, clear-headedness and good sense (which are the qualities an economist should have).” The admiration that Keynes expressed for Montesquieu in that document led me to undertake an investigation of Montesquieu's works. This research has made it possible to show that Montesquieu, though never fancying himself as an economist, had been creatively concerned with a crucial economic problem: the comparative statics of economic welfare.
Keynes was conscious mainly of Montesquieu's interest theory. He admired this theory in passing in the French Preface, but mentioned in no other of his works the influence that Montesquieu had on him. Nowhere did Keynes undertake to elaborate on or indeed justify any of his extraordinary remarks about Montesquieu. There is no reference to Montesquieu in the text proper of either the English or the French edition of the General Theory, or in any other of Keynes's works. As it stands, Keynes's sudden conviction that Montesquieu was the greatest French economist is hardly convincing. In this essay on attempt has been made to collect some of the evidence necessary for us to appraise the economic work of Montesquieu. I hope to vindicate the introduction of Montesquieu as an economist to the Anglo-Saxon world and to put Keynes's extraordinary contentions into proper perspective.