I am a Cornucopian, which is the opposite of a Malthusian. The term was coined to define the position of economist Julian Simon whose famous wager with doomsayer Paul Ehrlich in a sane world would would have put paid to the Malthusian predictions of the latter. (You can see more about the Simon-Ehrlich wager here.) A Malthusian says that population growth (especially of Irish, Hindoos and Negroes) leads to disastrous scarcity of resources, resulting in mass famine, war, and apocalyptic megadeath. A Cornucopian says that population growth, while it creates dislocations and even disasters (such as the enclosure laws of England) does not necessarily lead to the scarcity of any particular resource, nor all of them.
More people does not mean less stuff.
Let me make a startling suggestion -- that we look at the evidence that overpopulation exists, ever had existed, or ever will exist.
What evidence is there?
Certainly there are crowded and miserable places on the Earth. There are also crowded and wealthy places. What factors or conditions are present in the one case and not in the other? Is population the only contributing factor, or are there others? Are there any factors that mitigate the alleged miseries provoked by population growth?
(Let us please not use analogies to beasts without reason, who do suffer from cycles of overpopulation and diebacks. Such beasts do not have the capacity to plan for the future and adjust current behavior.)
Let us instead look at periods in history. To take a very early example, hunter-gatherer tribes could not sustain more than perhaps a few score souls on the same number of acres, devoted to hunting, which could support ten or twenty times that number of herdsmen.
The figure is even higher when the same number of acres is turned to agriculture, and higher again when the same number of acres, now including minerals beneath the soil, is used by a technological extended order.
Looking at the history, the first and most obvious fact is that what constitutes a natural resource changes, sometimes dramatically, from era to era, or even generation to generation. The hardwood forests of the north were not a natural resource to Paleolithic tribesmen, because stone handaxes were insufficient to chop down trees: and hence the paleolithic did not use carpentry to build log cabins or plane boards to build clapboard houses. The woods may have been a resource to them, but the wood was not.
The Precolumbian Indians of North America, on the other hand, included settled tribes and villages of farmers (for some odd reason, this is often overlooked by popular histories) who used forestfires to clear land for cultivation. The woods were not a natural resource to the farming tribes, not in the same way, not used the same way, and therefore not of the same value, as the hunter-gathering nomads.
The White Man not only put these lands to cultivation, but did so under an political and economic regime which secure the landowners in the titles, and allowed for those titles to be bought and sold. You may not notice that this, and only this, is what makes land a good. Under more primitive legal codes (such as those in Sharia Law or Biblical Law) land is not alienable except for a term (the Law of Moses sets the term at 50 years: between Jubilees) or cannot lay fallow (under Sharia Law, if memory serves, unused land must be turned over to the poor). Without debating the spiritual wisdom of either the Law of Moses or the Prophet of the Saracens, from an economic point of view their regime of laws renders ownership and exploitation of law more difficult, and hence, less efficient, and hence more scarce, and hence more dear in price, and hence less able to support the same population numbers.
Land under cultivation ruled by English Common Law is more efficient, and hence less scarce (in an economic sense) than the same number of acres of similar situation and fertility being cultivated under, say, the laws and customs of Bourbon France or Elizabethan Ireland, where the landowners were not secure in their ownership. The modern age has also seen the diabolical and stupid phenomenon of re-barbarism, where formerly civilized people would adopt regimes of laws and customs even less well suited for securing ownership than the laws and customs of the Bronze Age: I refer here to the famines of Stalinist Russia, or the economic ruin of Nazi Germany. (The policies of the national socialist workers party even before the war were eroding the economic strength of Germany.)
So then: whatever overpopulation is, is not necessarily (or even primarily) related to the number of people using a given number of acres of land. Bronze Age tribesmen had to separate their herd and minions when they were in danger of overgrazing the terrain -- see the Biblical story of Lot and Abraham separating their kin and kine for an echo of such events. But the same acres fenced in (assuming the society can survive the range wars and the injustices of the enclosure laws) can support many more people if used for crop rather than cattle.
So what is the upper limit? I humbly suggest that depends not on any absolute value, but on the use to which the land is put. Overpopulation is a relative value. Too many hunters is not too many herdsmen is not too many husbandmen, is not too many factory hands.
The same line of reasoning applies with equal logic to other goods aside from land.
Oil, in the modern day a byword for a scarce resource, before the days of John D. Rockefeller was not in high demand, and not used for much. Whale oil, on the other hand, was used for kerosene lamps, which was many a home's only source of light. Ambergris was in high demand, and of course whalebone was the only substance to be used in buggy whips and corset stays. In those days petroleum was a waste product which, if it seeped to the surface, ruined the soil for cultivation. Land known to have oil deposits below hence were depressed in value, not raised in value. Oil was not only not a resource in those days, it was actually useless.
Now you may have noticed that the demand for kerosene oil, ambergris, buggy whips and corset stays has dropped. The technology and the economics touching the natural resource known as whales has changed dramatically. We can make buggy whips more cheaply out of synthetic materials, such as plastics refined from petroleum. Some of us do not use buggy whips, or indeed, own a horse at all.
What is true of land and oil is true generally. The utility of any natural resource depends not on its volume, but on the efficiency of its use. The best rule of thumb for measuring utility is price. The more scare something is, the more dear its price. Natural resources that we are running out of, are ones we are getting low on, and, if the efficiency of use is not a factor, the price should go up.
But let us look at the evidence: the price adjusted for inflation (which is a type of tax, and therefore not an indicator of real prices) of metals over the last twenty years, including iron, steel, zinc, aluminum, uranium, has dropped. This means they are less dear ergo easier to acquire. In practical terms, they are more abundant.
Sand is not a natural resource when and if it serves no human need. But the silicon to make sand into computer chips is a resource.
Again, let us look at evidence. How many famines were caused (causes solely) by overpopulation? The potato famine in Ireland was not caused by (or not only by) a superabundance of Irish people. The laws of the English conquerors and the uncertainty of the times made cultivation dear. The grain famine in the Ukraine was not only not caused by overpopulation, it was caused by Stalin, in order to demoralize and terrify the Kulaks, and also in pursuit of his abortive millennial pseudo-economic pseudo-religion known as communism.
Which wars were caused by overpopulation? We can see population pressures behind some of the migratory movements of nomads into the crumbling corpse of the Roman Empire, but what does the evidence suggest? Something other than mere numbers must be involved, because otherwise Rome would not have been able to sustain a population greater than any population of London before the Industrial Revolution.
Compare the evidence with the fears. The calculations of Malthus should have had us suffering mass starvation a century ago; and the hysteria of Paul Ehrlich was such that he foresaw famines in India so severe that nothing could be done to save them -- Ehrlich wrote off the Indian subcontinent as lost. They would not survive past 1970.
(Ironically, or as proof that the devil exists and has a sense of humor, Ehrlich made headlines again recently by predicting another population bomb about to go off in the near future, and this time for sure there would be mass starvation! This exposed hoaxster is applauded and lauded wherever he goes. His predictions are as accurate as prophets who foretell the date of the Second Coming of Christ.)
Compare the evidence with the fear. Robert Heinlein, writing in the 1940's and 1950's, confidently proposed that all social maladies, wars and migrations, were tied into overpopulation. Beef and poultry would be gone by the 1980's, and by the year 2000 mass starvation and the rationing of foodstuffs would be commonplace. Instead, one of the chief medical maladies among American below our arbitrary poverty line is obesity, and maladies related thereto. The main medical problem among the poor is that food is so plentiful and so cheap that they eat too much of it.
In case my point here is not clear, let me simplify it, even if I run the risk of not mentioning the various reservations and qualifications that surely exist: Malthus was a crackpot, an intellectual on par withe Xeno, who proved that an arrow flying at a wall could never reach it, because it must fly through an infinite number of intermediate points. Ehrlich was and is a Rachel-Carson-type fraud, a used car salesman, and suffers the curse the reverse of Cassandra: the more inaccurate his predictions, the more fixedly people believe him.
Overpopulation is a meaningless concept. It is the fear that every new baby is a new mouth to feed. But every new baby is also a new pair of hands to work, once the baby grows. The question is whether the baby will produce more than he consumes over his lifetime. The fear of Malthus and Ehrlich is that he likely will not. The evidence of history is that he most likely will.
This fear is merely assumed, never stated, and never defended, and never proved. Where is the evidence? Where is the proof?
The argument at this point becomes whether a technological civilization has some innate property that previous arrangements (husbandmen, herdsman, hunter-gatherer) did not have. Is there something about digging metals out of the ground different from hunting Mastodons? I suggest that the difference is one favorable to the moderns.
The hunters of the Last Ice Age, Noble Savages to a man, hunted the Mastodon to extinction. One must assume they suffered a dieback or that the found another source of food. It is an open question whether the ability of a large tribe (a so-called overpopulated tribe) to find a new food source is greater or less than that of a small tribe. Numbers surely were an aid rather than a drawback when it came to overwhelming the Neanderthals, for example, or wiping out tribes seated in sunnier southern climes.
We in the Iron Age dug up iron in large amounts. In the Space Age, certain Space Age materials are used where Iron was once used, albeit, judging from the real price, iron is cheaper, and more abundant than ever. In other words, if the moderns were faced with overhunting of Mastodons, our greater organization, our market place methods, would seek alternatives. Our habit of innovation, our protection of intellectual property rights, encourages new approaches when shortages arise. We can change our laws and habits. Scattered and non-unified nomads of different clans and distant tribes cannot change their oral folk-law and standards of behavior so quickly.
Looking over America, there seem to be more trees on more acres than there ever were even during the days of the American Indian tribes while they were dancing with wolves and painting in all the colors of the wind.
Hence, in Modern Times, with a larger population in America, we have more resources, and not less. The conclusion seems counter-intuitive, but almost all economics is counter-intuitive.
Let me propose another counter-intuitive principle. A finite material resource is not a finite resource. If I have an acre of timber, and I use a half acre for firewood, so that it is consumed and burnt, but I use a quarter acre to make a ship to sail to El Dorado, the benefit from the quarter acre far exceeds the benefit from the half acre because I used it more wisely -- even though a quarter acre is less than a half acre, not more. A ship is worth more than the same amount of lumber sold as cords of firewood.
Here is the key concept: if nature is a larder or a treasure box that has only so many smoked sausages and cheese wheels to consume, or only so much gold to take out of the box, then common sense says the more you take out of the larder or the treasure box, the less remains to take out in days to come: and then one day the larder will be empty and the treasure box will be bare.
But if nature is like a field, where if you grow thistles and thorns, you have little to eat, and if you grow potatoes, you have more to eat, and if you grow poppies, you can sell opium to the Americans and get rich, and if you dig under the field and strike oil, strike gold or strike uranium, you are richer still. Suppose the field is one where kine cannot graze but ostriches can; and suppose again you develop a taste for ostrich meat, then the exact same field, the exact same resources, if even some are used up, offers other resources to be exploited, including material objects that, under earlier regimes and technologies, were not resources at all.
Let me utter a parable. Once upon a time, the wise men of the Napoleonic era saw the devastation Napoleon wrought upon all the famous families and breeds of horses. Warhorses of well-bred stock were dying in his wars, and not being replaced. Horses did not breed as rapidly as men, and the Malthus of that era, by a simple mathematical calculation, could show that horses were being used up faster then they were being replaced. Meanwhile men were breeding like rats, so, mathematically, the chance that any particular man could grow up to be a cavalry officer with a good horse would get ever smaller. If the trend continued, the horse would be extinct by the year 1902!
Napoleon, alarmed by Malthus, asked science fiction writer Jules Verne what could be done?
Verne said that the men of the future would have some sort of mechanical horse, or horseless carriage powered by steam, or some sort of flying machine, or something unimaginable. The cavalry of the future, said Verne, would not have any horses in it at all, but would instead have a land version of an ironclad warship, a Land Leviathan, which would walk the earth on treads.
Absurd! Said Napoleon. Without horses, the ice wagon will not be able to carry ice from house to house to put ice blocks into ice boxes. And if there are no wagons, the buggy-whip manufacturers will go out of business! And with no wagons, there will be no way to bring whalebones from the sail-powered whaling ships to the seamstresses to make corset stays -- surely you will not tell me that the women in the future will not wear corsets! Do you think they will dress like savages in Tahiti, or wear drab dungarees?!
But, Verne answered him, if you do not believe me, buy horses. As the horse dies off, their price per horse will go up, and you will be rich.
To Malthus, he said, if you think we are about to run out of oil, buy oil. If you think we are running out of land, buy land. If you think we are running out of steel, coal, zinc, aluminum, buy them.
But if you buy them and they turn out not to be scarce -- scarce measured by the human need we have for them, and nothing else! -- then you will be ruined.
If you had listened to Paul Ehrlich when he wrote his famous work of overwrought scaremongering THE POPULATION BOMB, and bought up the materials he said would be gone by 1970, then instead of being rich, you would have been ruined. If you had listened to Malthus in 1776 and, based on his mathematical calculation that human population increases geometrically whereas land is placed under cultivation only by arithmetic growth, you would have invested in farmland. You would now be broke, because one man with a tractor, using modern scientific methods of cultivating the soil, can do the work of a team of horses and farmers, and so the relative price of manpower, horsepower, and an acre of cultivated land fell rather than rose.
Suppose a crackpot idea like Cold Fusion had worked. Suppose a crackpot idea like aquaculture could work, and the surfaces of all the oceans of the world, 70 of the Earth's surface, could be used to feed hungry populations. Suppose global warming is a fact, and it is about to happen, and the temperature changes will make Siberia, the Gobi desert or the Sahara open to cultivation. Suppose America lifts the bans it has in place to prevent the drilling for oil and the exploration of uranium found in our own soil, or just offshore. Suppose some genius discovers an even cheaper and more effective solar panel. Or just suppose someone invents a more efficient battery, a better way to store power once generated, easier to ship, so the price of transmitting energy across distances by wire drops.
Suppose any of these things. What happens to the price of oil then? It is less in demand, and its price drops like a stone.
Suppose the opposite happens, and the price of oil sky rockets. Extracting oil from shale, currently not an economic proposition, becomes an economically feasible venture. As more men and thought flows into the shale oil field, improvements and inventions in that venture are likely, in which case the price will again drop.
I sincerely doubt our current civilization has achieved the best and final means of exploiting the natural resources of the Earth. Even without daydreaming about Star Trek like inventions that can turn inanimate matter into editable substances, the current inefficiencies surrounding our social and legal institutions in America, the absence of something like enclosure laws to section off the vast wastelands of the ocean, the endless acres of wasteland currently not economic to exploit -- I have good reason to hope that we are nowhere near reaching the limit of population on the Earth, and I scoff at the notion that any one resource is so irreplaceable that once it is gone, human genius can find no substitute.
Suppose all the tin runs out! Shall we made no more tin cans? Will there be no companies like Alcoa, who might make cans out of aluminum instead? Suppose the whalebone runs out! Can we make corset stays of nothing else? Will there be no mad geniuses like Howard Hugh to invent the Maidenform bra that lifts and separates?
I do not believe the “nature as a larder box” metaphor of natural resources.
For all practical purposes, under regimes and laws where human genius is free to discover new solutions to shortages, and when the market is free to raise and lower prices to signal where real shortages obtain, and where a futures market is able to operate to render scarce goods more expensive thereby preserving those needed for future use from current use, then the mere physical limits on land, on oil, on metals, or on any other good you care to name, serve no limit to human population growth.
In other words, when man is free, then Natural resources are infinite.