Which of these two theories is entitled to historical precedence it is hard to say. The theory of population was not formulated in such a way as to give it the standing of a scientific dogma until after that had been done for the theory of wages. But they naturally spring up and grow with each other, and were both held in a form more or less crude long prior to any attempt to construct a system of political economy. It is evident, from several passages, that though he never fully developed it, the Malthusian theory was in rudimentary form present in the mind of Adam Smith, and to this, it seems to me, must be largely due the misdirection which on the subject of wages his speculations took. But, however this may be, so closely are the two theories connected, so completely do they complement each other, that Buckle, reviewing the history of the development of political economy in his Examination of the Scotch Intellect During the Eighteenth Century, attributes mainly to Malthus the honor of “decisively proving” the current theory of wages by advancing the current theory of the pressure of population upon subsistence. He says in his History of Civilization in England, Vol. 3, Chap. 5:
“Scarcely had the Eighteenth Century passed away when it was decisively proved that the reward of labor depends solely on two things; namely, the magnitude of that national fund out of which all labor is paid, and the number of laborers among whom the fund is to be divided. This vast step in our knowledge is due, mainly, though not entirely, to Malthus, whose work on population, besides marking an epoch in the history of speculative thought, has already produced considerable practical results, and will probably give rise to others more considerable still. It was published in ; so that Adam Smith, who died in , missed what to him would have been the intense pleasure of seeing how, in it, his own views were expanded rather than corrected. Indeed, it is certain that without Smith there would have been no Malthus; that is, unless Smith had laid the foundation, Malthus could not have raised the superstructure.”
The famous doctrine which ever since its enunciation has so powerfully influenced thought, not alone in the province of political economy, but in regions of even higher speculation, was formulated by Malthus in the proposition that, as shown by the growth of the North American colonies, the natural tendency of population is to double itself at least every twenty-five years, thus increasing in a geometrical ratio, while the subsistence that can be obtained from land “under circumstances the most favorable to human industry could not possibly be made to increase faster than in an arithmetical ratio, or by an addition every twenty-five years of a quantity equal to what it at present produces.” “The necessary effects of these two different rates of increase, when brought together,” Mr. Malthus naively goes on to say, “will be very striking.” And thus (Chap. I) he brings them together:
“Let us call the population of this island eleven millions; and suppose the present produce equal to the easy support of such a number. In the first twenty-five years the population would be twenty-two millions, and the food being also doubled, the means of subsistence would be equal to this increase. In the next twenty-five years the population would be forty-four millions, and the means of subsistence only equal to the support of thirty-three millions. In the next period the population would be equal to eighty-eight millions, and the means of subsistence just equal to the support of half that number. And at the conclusion of the first century, the population would be a hundred and seventy-six millions, and the means of subsistence only equal to the support of fifty-five millions; leaving a population of a hundred and twenty-one millions totally unprovided for.
“Taking the whole earth instead of this island, emigration would of course be excluded; and supposing the present population equal to a thousand millions, the human species would increase as the numbers 1, 2, 4, 8, 16, 32, 64, 128, 256, and subsistence as 1, 2, 3, 4, 5, 6, 7, 8, 9. In two centuries the population would be to the means of subsistence as 256 to 9; in three centuries, 4,096 to 13, and in two thousand years the difference would be almost incalculable.”
Such a result is of course prevented by the physical fact that no more people can exist than can find subsistence, and hence Malthus’ conclusion is, that this tendency of population to indefinite increase must be held back either by moral restraint upon the reproductive faculty, or by the various causes which increase mortality, which he resolves into vice and misery. Such causes as prevent propagation he styles the preventive check; such causes as increase mortality he styles the positive check. This is the famous Malthusian doctrine, as promulgated by Malthus himself in the Essay on Population.
It is not worth while to dwell upon the fallacy involved in the assumption of geometrical and arithmetical rates of increase, a play upon proportions which hardly rises to the dignity of that in the familiar puzzle of the hare and the tortoise, in which the hare is made to chase the tortoise through all eternity without coming
