Note 364:1 — Chapter VIII

Dr. Robert Wallace, a distinguished clergyman of the Church of Scotland, had prepared for the Philosophical Society, of which he was a member, an essay, which he enlarged and published in 1752, with the title, "Dissertations on the Numbers of Mankind in Ancient and Modern Times;" adding a supplement, in which he examined Hume's discourse on the Populousness of Ancient Nations. Malthus admitted that Dr. Wallace was the first to point distinctly to the rule, that to find the limits of the populousness of any given community, we must look at the quantity of food at its disposal. But he was not successful in the controversial application of his principle. Hume's method of inquiry is a double comparison. The statements of numbers in ancient authors being compared with the numbers in existing communities, the relative organization for the supply of food in the two cases is examined, and the author finds reason to believe that the statements of numbers are greatly exaggerated by ancient authors, as the state of commerce and transit, and the amount of stock or capital available for the concentration and distribution of food, are not such as would enable such multitudes to be supported. Dr. Wallace, laying down, that where there is the most food there will be the greatest number of inhabitants, maintains, that as a much greater proportion of the people were employed in agriculture among the ancients than the moderns, there must have been more food and consequently more human beings. It is almost needless, after so much has been written on this matter, to explain at length the fallacy of this reasoning. The richest and most populous states are those of which the smallest proportion of the people are employed in agriculture. A decrease of the comparative number employed in procuring the necessaries of life is the mark of increase in wealth and abundance of all things, and is necessarily accompanied either by a proportionally improved agriculture, or the purchase of food from poorer communities.

In the subsequent editions of the "Discourses," Hume acknowledges the merit of Wallace's book, saying, "So learned a refutation would have made the author suspect that his reasonings were entirely overthrown, had he not used the precaution, from the beginning, to keep himself on the sceptical side; and, having taken this advantage of the ground, he was enabled, though with much inferior forces, to preserve himself from a total defeat."