The name of Malthus will forever be associated with the idea of resource constraints on human population growth– which is unfortunate, because his argument appears to have been completely wrong. But I feel a need to compensate a bit for my little essay on those mistakes after reading John Maynard Keynes’ delightful biographical sketch of Malthus. Keynes offers an alternative intellectual history of Malthus, in which the Essay on the Principle of Population appears as a youthful work that gave him much notoriety, but was far from his most significant intellectual accomplishment.

It is difficult to overstate just how good Keynes’ essay on Malthus is: it is wonderfully detailed yet short, warmly sympathetic yet intellectually sharp. (Among other tidbits, we learn the name of Malthus is derived from “Malthouse,” and should be pronounced similarly.) Tyler Cowen has called Keynes “one of the greatest biographical writers in the entire English language.” And indeed I found Keynes’ Essays in Biography to be very good, though the meat of it is really the biographical essay on Malthus and a more extended one on Alfred Marshall; the sketches of British politicians for me were less interesting and insightful.

Keynes claims Malthus as his intellectual forebear, “the first of the Cambridge economists,” on the strength of Malthus’ early attention to the demand side of the economy, and his invention of the concept of “effective demand,” a precursor to today’s “aggregate demand.” As far back as 1820, in his Principles of Political Economy, Malthus recommended “the employment of the poor in roads and public works” as a remedy to economic downturns. But the first appearance of this idea actually came in 1800, in an anonymous pamphlet called An Investigation of the Cause of the Present High Price of Provisions:

Malthus’s conception of “effective demand” is brilliantly illustrated in this early pamphlet by “an idea which struck him so strongly as he rode on horseback from Hastings to Town” that he stopped two days in his “garret in town,” “sitting up till two o’clock to finish it that it might come out before the meeting of parliament.” He was pondering why the price of provisions should have risen by so much more than could be accounted for by any deficiency in the harvest. He did not, like Ricardo a few years later, invoke the quantity of money. He found the cause in the increase in working-class incomes as a consequence of parish allowances being raised in proportion to the cost of living. …

The words and the ideas are simple. But here is the beginning of systematic economic thinking.

Keynes found that Malthus’ economic thinking was best developed in his long correspondence with David Ricardo, a relationship that managed to combine deep and sincere friendship with equally profound intellectual disagreement:

This friendship will live in history on account of its having given rise to the most important literary correspondence in the whole development of Political Economy. … Here, indeed, are to be found the seeds of economic theory, and also the divergent lines—so divergent at the outset that the destination can scarcely be recognised as the same until it is reached—along which the subject can be developed. …

The contrasts between the intellectual gifts of the two were obvious and delightful. In economic discussions Ricardo was the abstract and a priori theorist, Malthus the inductive and intuitive investigator who hated to stray too far from what he could test by reference to the facts and his own intuitions. …

One cannot rise from a perusal of this correspondence without a feeling that the almost total obliteration of Malthus’s line of approach and the complete domination of Ricardo’s for a period of a hundred years has been a disaster to the progress of economics. Time after time in these letters Malthus is talking plain sense, the force of which Ricardo with his head in the clouds wholly fails to comprehend. Time after time a crushing refutation by Malthus is met by a mind so completely closed that Ricardo does not even see what Malthus is saying.

Malthus’ strengths, on Keynes’ account, are his close attention to the realities of economic life and his detailed investigation into practicalities, which gave him insights that Ricardo’s abstractions could not. It’s interesting, therefore, that he characterizes Malthus’ first writings on population as “a priori and philosophical in method,” the precise terms in which he criticizes Ricardo’s arguments.

While Malthus added huge amounts of empirical material to the second edition of the Essay on the Principle of Population, it is clear that the inspiration for the first edition was not empirical. It was more of an abstract conviction, one that arose during a theological argument with his father. William Otter, a friend of Malthus, relates the story in his Memoir of Robert Malthus:

The mind of Mr. Malthus was certainly set to work upon the subject of population, in consequence of frequent discussions between his father and himself respecting another question, in which they differed entirely from each other. The former, a man of romantic and somewhat sanguine temper, had warmly adopted the opinions of Condorcet and Godwin respecting the perfectibility of man, to which the sound and practical sense of the latter was always opposed; and when the question had been often the subject of animated discussion between them, and the son had rested his cause, principally upon the obstacles which the tendency of population to increase faster than the means of subsistence, would always throw in the way; he was desired to put down in writing, for maturer consideration, the substance of his argument, the consequence of which was, the Essay on Population.  

Keynes does not discuss whether Malthus’ theory of population–that it would always grow exponentially while food production could only grow linearly–was actually correct, seeing it mainly as an early example of the power of his intellect. When the early work on population is considered along with the later work on political economy, the intellectual contrast with Ricardo is perhaps not as sharp as Keynes makes it out to be: Malthus too could be bullheaded in holding to his a priori theories in the face of contrary argument. But who among us has not been guilty of that?