Sunday, May 8, 2016

Excerpt from "Progress Debunked": Malthus's Principle Explained

1. The Birth of Progress. 

The modern theory of progress originated in the late 1700’s, also known as “The Enlightenment,” a period of social upheaval in the West. Monarchy ultimately gave way to democracy, feudalism to capitalism and socialism, fundamentalism to free thought, tradition to science. These transformations did not come without a price in violence. A Revolution in the Thirteen Colonies soon helped inspire the still more bloody Revolution in France, where the philosophical debate over the possibility of utopia would achieve unprecedented heights of brutality.

Living in exile, hiding from a death sentence pronounced by his political opponents (soon to be carried out) the Marquis de Condorcet, a brilliant polymath whose radical notion of progress had made him many enemies, penned perhaps the most influential argument for progress written so far, Outlines of an Historical view of the Progress of the Human Mind.

He wrote, somewhat prophetically, that “truths appertaining to the sciences of observation, calculation and experiment, may be perpetually augmented” so that “instruments, machines, looms, will add every day to the capabilities and skill of man” and “the same manufactured or artificial commodity will be produced at a smaller expence of raw materials.” This was already happening with steam engines and textile factories in England and France, and the increases in standards of living seemed to promise a brighter, more prosperous future.

But objections to progress based on population growth were already common currency, and Condorcet seemed to consider this a troubling challenge for his theory of progress:

[I]t may, I say, be demanded [...] [w]hether the number of inhabitants in the universe at length exceeding the means of existence, there will not result a continual decay of happiness and population, and a progress towards barbarism, or at least a sort of oscillation between good and evil? Will not this oscillation, in societies arrived at this epoch, be a perennial source of periodical calamity and distress? In a word, do not these considerations point out the limit at which all farther improvement will become impossible, and consequently the perfectibility of man arrive at a period which in the immensity of ages it may attain, but which it can never pass?

Reverend Thomas Malthus would later take these doubts to heart. He would not be consoled reading Condorcet’s two-sentence dismissal:

There is, doubtless, no individual that does not perceive how very remote from us will be this period: but must it one day arrive? It is equally impossible to pronounce on either side respecting an event, which can only be realized at an epoch when the human species will necessarily have acquired a degree of knowledge, of which our short-sighted understandings can scarcely form an idea.

Few writers felt this “question of population” to be important enough to face directly. William Godwin called the debate “considerably curious.” In his own book on the future social progress of Europe, An Enquiry concerning Political Justice, he wrote:

Several writers upon these topics have treated it in a way calculated to produce a very gloomy impression, [but] [t]here is a principle in the nature of human society, by means of which everything seems to tend to its level. [...] There are various methods by the practice of which population may be checked; by the exposing of children, as among the ancients, and, at this day, in China; by the art of procuring abortion, as it is said to subsist in the island of Ceylon; by a promiscuous intercourse of the sexes, which is found extremely hostile to the multiplication of the species; or, lastly, by a systematical abstinence, such as must be supposed, in some degree, to prevail in monasteries of either sex. But, without any express institution of this kind, the encouragement or discouragement that arises from the general state of a community, will probably be found to be all-powerful in its operation.

Like Condorcet, Godwin didn’t find population doubts particularly troubling. He concluded his brief chapter on population by saying, “however [...] to reason thus, is to foresee difficulties at a great distance.”

As Malthus would come to see it, these “difficulties” were not remote at all, but ever-present in all nations throughout history, for all animals, plants, and humans. For him there was a mathematical principle involved, which he would call the Principle of Population, that he believed absolutely barred the way to progress and utopia.

2. Malthus’s Principle. 

In Chapter 1 of his Essay on the Principle of Population, Malthus laments: “The really good arguments on each side of the question are not allowed to have their proper weight. Each pursues his own theory, little solicitous to correct or improve it by an attention to what is advanced by his opponents.” His goal was to finally put the question on solid ground:

I think I may fairly make two postulata.
First, That food is necessary to the existence of man.
Secondly, That the passion between the sexes is necessary and will remain nearly in its present state. (Malthus, 1798)

Malthus chose these “postulata” or “assumptions” to be as simple and self-evident as possible. From the standpoint of physics, they do lack mathematical formulation. For example, “passion between the sexes” is not an obviously measurable quantity. But from what follows it becomes clear enough what he means, and his theories on population growth are still widely cited by biologists, sociologists, and other scientists:

Population, when unchecked, increases in a geometrical ratio. Subsistence increases only in an arithmetical ratio. A slight acquaintance with numbers will shew the immensity of the first power in comparison of the second.
By that law of our nature which makes food necessary to the life of man, the effects of these two unequal powers must be kept equal.
This implies a strong and constantly operating check on population from the difficulty of subsistence. This difficulty must fall somewhere and must necessarily be severely felt by a large portion of mankind. (Malthus, 1798)

Population has a tendency to grow exponentially. If every couple has four children, for example, and this trend continues, you’re doubling the population every generation. Exponential growth means your rate of increase is itself increasing. The more people you have the more people you add each generation. Two grows by two, four grows by four, eight grows by eight.

Food production, on the other hand, depends on the availability of land. The more land is used, the less land is available. At best, in Malthus’s view, your food resources will grow “arithmetically,” that is, by adding a constant value. Two grows by two, four grows by two, eight grows by two.
Since population grows faster, Malthus’s theory says that there will be a “strong and constantly operating check on population.”

For Malthus, this dilemma determines whether you can create a utopian society without any misery. As long as the dilemma stands, progress toward utopia is impossible. He wrote, “All other arguments are of slight and subordinate consideration in comparison of this.”

Malthus notes that this process of population checking is seen throughout nature:

Through the animal and vegetable kingdoms, nature has scattered the seeds of life abroad with the most profuse and liberal hand. She has been comparatively sparing in the room and the nourishment necessary to rear them. The germs of existence contained in this spot of earth, with ample food, and ample room to expand in, would fill millions of worlds in the course of a few thousand years. Necessity, that imperious all pervading law of nature, restrains them within the prescribed bounds. The race of plants and the race of animals shrink under this great restrictive law. And the race of man cannot, by any efforts of reason, escape from it.

Trees produce thousands of seeds at time, every garden plant produces several seeds, if not dozens upon dozens. Cats and dogs breed in litters. Every animal wild or domesticated, left to breed freely, will over time produce more than two offspring per mother. We know that if these populations were not checked by resource limits, they would grow out of control. What we have, then, is a law that applies to all of animate nature, including humankind.

Malthus estimated that the human population, without any checks, would double every 25 years. That meant that no matter how fast your food supplies grew initially, eventually your doubling population would catch up.
Illustration 1: How population would grow if unchecked by food shortage, according to Malthus. (Hypothetical scenario.)

3. Proof by Contradiction, not Prophesy. 

Malthus’s argument may seem clear enough, but it is widely misunderstood. He introduced his principle to refute the idea of progress, to debunk “the perfectibility of man.” But charts like Illustration 1 above have led to the popular belief that he was predicting a future calamity, where the population will become so great that everyone must starve. This “prophetic” reading has been encouraged by pseudo-Malthusian works with titles like The Population Bomb (Ehrlich, 1968). This might explain why over the last century his relevance to the question of progress has been neglected. For instance, Nobel-prizing winning economist Amartya Sen (1999) writes:

Is the world food output falling behind world population in what is seen as a “race” between the two? The fear that this is precisely what is happening, or that it will soon happen, has had remarkable staying power despite relatively little evidence in its favor. Malthus, for example, anticipated two centuries ago that food production was losing the race and that terrible disasters would result from the consequent imbalance in “the proportion between the natural increase of population and food.” He was quite convinced, in his late-eighteenth-century world, that “the period when the number of men surpass their means of subsistence has long since arrived” (Sen, 1999, p. 205).

Ironically, his quotation—“the period when the number of men surpass their means of subsistence has long since arrived”—is actually taken from a context where Malthus is arguing against Condorcet’s tendency to treat population arguments as prophetic:

Mr. Condorcet’s picture of what may be expected to happen when the number of men shall surpass the means of their subsistence is justly drawn. The oscillation which he describes will certainly take place and will without doubt be a constantly subsisting cause of periodical misery. The only point in which I differ from Mr. Condorcet with regard to this picture is the period when it may be applied to the human race. Mr. Condorcet thinks that it cannot possibly be applicable but at an era extremely distant. If the proportion between the natural increase of population and food which I have given be in any degree near the truth, it will appear, on the contrary, that the period when the number of men surpass their means of subsistence has long since arrived, and that this necessary oscillation, this constantly subsisting cause of periodical misery, has existed ever since we have had any histories of mankind, does exist at present, and will for ever continue to exist, unless some decided change take place in the physical constitution of our nature. (Malthus, 1798)

In other words, the human population is already subject to continual and powerful Malthusian checks, and unless we somehow overcame these checks there would be no progress. A graph better illustrative of his view would look like this:
Illustration 2: How population is checked by food shortage, according to Malthus. (Hypothetical scenario.)

What, then, is the point of passages like this in Malthus’s Essay:

[T]he human species would increase in the ratio of—1, 2, 4, 8, 16, 32, 64, 128, 256, 512, etc. and subsistence as— 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, etc. In two centuries and a quarter, the population would be to the means of subsistence as 512 to 10: in three centuries as 4096 to 13, and in two thousand years the difference would be almost incalculable.

What is being mistaken for a prophecy here, is really what logicians call a reductio ad absurdum, (Latin for “reduction to absurdity”) against his opponents’ view. He is saying that there must be checks of some sort operating on the human population, because if there were not there would already be far more people than you could feed. His conclusion to the above argument is that “the increase of the human species can only be kept commensurate to the increase of the means of subsistence by the constant operation of the strong law of necessity acting as a check.” He’s referring to existing poverty, hunger, disease and vice—obstacles to survival and successful child-rearing. He wasn’t speaking of the increase of such things in the future, but rather their constant quantity throughout history up to the present, representing what is imperfect in humankind that cannot ever be eliminated.

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