Should We Worry about Overpopulation?--Posner

This posting is stimulated by comments made about my passing reference to overpopulation in Subsaharan Africa in the recent blog on DDT and by an article in the Wall Street Journal last week called "The Coming Crunch" that notes with concern a prediction that the population of the United States will reach 400 million in 35 years. Concerns about overpopulation are ridiculed by conservatives because of the mistaken predictions by Paul Ehrlich (not to mention Thomas Malthus!) in his book The Population Bomb and by other anticapitalists since the first Earth Day (1970), and have spread to liberals because the only way to slow or stop the growth of the U.S. population is by curtailing immigration (e.g., the "fence"). Although I have been strongly critical of the shoddy arguments of Ehrlich and other doomsters (in my book Public Intellectuals), I believe that overpopulation is a serious issue and deserves dispassionate analysis. Just because the problem of overpopulation has been exaggerated in the past doesn’t mean it is not a problem today. The future may not resemble the past. The belief that the mistakes of Malthus, Ehrlich, and other past prophets of doom show that current concerns with overpopulation are unfounded is on a par with the belief that we shouldn't worry about terrorism because many fewer Americans have been killed by terrorists than in automobile accidents. Such arguments confuse frequencies (the past) with probabilities (the future). Economists stress the "demographic transition," that is, the tendency of the birth rate to decline steeply as a nation becomes wealthier. But apart from the fact that not all nations experience significant economic growth, such growth tends, other than in Europe and Japan, not to make the rate of population growth zero or negative. Most demographers forecast that world population, currently somewhat more than 6 billion, will rise to between 9 and 14 billion by mid-century. I shall address the following questions: what are the costs of population increase (1) to the country in which the increase occurs, (2) if that country is the United States; and (3) to other countries; (4) what are the benefits to the country in which the increase occurs and (5) to other countries; and (6), when the costs exceed the benefits, what if anything should be done to slow or arrest population growth? 1. If the arable and otherwise inhabitable parts of a poor country are densely populated, increased population will result in significantly higher costs of food and other agricultural products by requiring more intensive cultivation, or cultivation of poor soil. It will also increase the cost of water, and time spent in commuting and other transportation. This seems to be the situation in India and much of Africa. And notice that China, though it is en route to becoming a wealthy country, has not abandoned its "one child" policy. That policy is an inefficient method of limiting population growth, but is evidence that China does have a problem of overpopulation. Surely India does as well, though like China its economic output is growing rapidly. 2. The United States is not densely populated, but that is only when density is computed on a nationwide basis, i.e., if the total area of the country is divided by the population. Particular areas, mainly coastal (including the Great Lakes coasts), are densely populated, and further population increases in those areas would increase commuting times, which have lengthened in recent years, and in some of these areas (such as California and Arizona) would place strains on the water supply. In principle, however, these problems can be solved by pricing, including greater use of toll roads. Increased commutes impose environmental costs, but tolls could be based on those costs. 3. The greatest costs of further population increases are likely to be costs external to individual countries and therefore extremely difficult to control by taxation or other methods of pricing "bads," because most of the benefits of these measures would be reaped by other countries. These are environmental costs, mainly global warming and loss of biodiversity, about which I have written at length in my book Catastrophe: Risk and Response (Oxford University Press, 2004). Of course, population growth per se does not increase global warming, but the burning of forests and, most important, of fossil fuels does, and these activities are positively correlated with population. Not only is it now the scientific consensus that global warming is a serious problem, but its adverse effects are appearing sooner than expected; it is by no means certain that a technological fix will be devised and implemented before the effects of global warming become catastrophic. 4. Population growth in productive societies increases the society's total output and hence its geopolitical power. It also has a positive effect on innovation by increasing the size of markets. Innovation involves a high ratio of fixed to variable costs (it costs hundreds of millions of dollars to develop a new drug, yet once it is developed, the drug may be very cheap to produce), so the larger the market for the innovative product or process the likelier are the fixed costs of invention to be recouped in sales revenues. Some people also believe that the larger the population, the more innovators there will be, assuming that a fixed percentage of the population consists of innovators, whatever the size of the population. This is a questionable argument for population growth, as it ignores the fact that a fixed percentage of the population presumably also consists of potential Hitlers and Stalins and Pol Pots, and thus the absolute number of these monsters grows with population growth. Moreover, a population increase that is due to a higher birth rate (as distinct from immigration) increases the number of young people in a society, who are impressionable and therefore more likely than older people to be drawn to extremist politics, including terrorism. In addition, greater competition among innovators may reduce the potential returns to each innovator by increasing the number of simultaneous innovations, and may thus reduce the incentives to innovate. The relationship between aggregate population and creativity seems in any event very loose. The citizen population of Athens in the fifth and fourth centuries B.C. was roughly 25,000, but produced intellectual and artistic works that dwarf those of entire continents. Furthermore, technological growth currently favors destructive over beneficial technologies. The increasing lethality and availability of weapons of mass destruction--the proliferation problem--has a greater short-term downside than benign inventions have an upside, especially since much innovative activity is focused on increasing longevity, and thus population. Policies that accelerate the rate of technological advance are dangerous unless the advance can somehow be channeled into productive forms. It cannot be. A dubious benefit of population growth is that it lowers the average age of the population and therefore the burden of the elderly. That is a Ponzi scheme rationale for encouraging growth of population, since as soon as the growth ceases, the average age will shoot up--especially if it is correct that population growth increases the rate of medical innovation and thus the life span! 5. An increase in one nation's power reduces the power of other nations; so there is again a negative externality. The increase in the world's Muslim population is a negative externality for non-Muslim nations, especially the European nations, with their shrinking or about-to-start-shrinking populations. But by the same token an increase in the non-Muslim population of Europe would probably be a boon for the European nations. And an increase in the rate of innovation in one nation will benefit other nations unless intellectual-property laws are extremely strict (which would have its own negative economic effects). 6. If, apart from poor countries, the major costs of population growth are external to the particular nations in which population is growing, there is very little that can be done, given the weakness of international institutions, which is due in turn to the number and diversity of nations that have to be coordinated for effective action against global problems. Moreover, limits on immigration do not reduce global population growth and thus do not respond to the global-warming problem. Rich countries, however, can aid poor countries to reduce their rate of population increase by encouraging family planning and, in particular, female education, since educated women have higher opportunity costs of fertility, and hence fewer children, than uneducated ones. Where, as in the United States, the costs of population increase are concentrated in particular areas (whether in geographical areas or along highways), the costs can be neutralized by increasing prices proportionally tied to density by taxation or other methods of pricing negative externalities.

Comments

[econgeek]

Judge Posner; In " The citizen population of Athens in the fifth and fourth centuries B.C. was roughly 25,000, but produced intellectual and artistic works that dwarf those of entire continents. " Which contients in particular do you have in mind? Not only does this seems a tab hyperbolic, but even what countries are you willing to make this statement about?

[Larry]

I disagree with much of Posner's argument, but he's write about Greece. The works of Herodotus, Thucydides, Aeschylus, Sophocles, Euripides, Aristophanes and Plato, among others, compares favorably with the output of many countries, and even continents.

[Lawrence Indyk, University of Kansas School of Law]

Dr. Becker presents the first of what I guess will be several arguments along these two lines.

(1) Past claims of imminent overpopulation catastrophes have been radically wrong and "therefore" current arguments should also be suspect. and

(2) Past technological improvements in agriculture and natural resource exploration and extraction have dramatically increased the number of humans who can live comfortably on this planet and "therefore" we should not be overly concerned with estimates of future resource scarcity or future environmental degradation. We live in an age of rapid technological progress and surely some unforseen technological solution will come through yet again to prevent us from "hitting the wall".

The first argument may have some validity in terms of rousing one's suspicions - but it is illogical to treat it as conclusive and allowing a dismissal of any future claim without a thorough analysis on its merits.

The second argument, however, seems to me more like magical thinking. You cannot take past technological progress trends and wish into existence some future development that will solve problems we would find intractable today. For instance, what to do when our fossil and fissionable energy reserves are expended if solar-derived energy is insufficient and practical fusion reactors are not developed in time?

These problems may indeed be solved one day, but isn't it better when faced with uncertainty to hope for the best but plan for the worst? It is fundamentally unwise when faced with upcoming unsolved problems to act on some unfounded optimism of future resolution. Or, at the very least, it is irresponsible to act on such optimism without also hedging one's bets and dedicating sufficient resources into the research and development of those solutions. It is also politically careless to avoid uncomfortable discussions about population today at the cost of potentially trapping our descendants with far more excruciating choices.

I do not claim that the human population is already above the planet's "carrying capacity" or that we are anywhere near the point where physical limits would constrain the ability of the whole global population to one day sustainably live our comfortable modern lifestyles. But it is a fact that there is some limit out there and if a serious claim is made of future scarcity then that claim and the measures required to mitigate the problem deserve thoughtful consideration.

[Richard Mason]

The truth is that many of the arguments made by Plato are not very clever and many of Aristophanes' jokes are not very funny (or just not accessible to us). We would not think much of them if advanced by a college undergraduate today.

It is difficult to make fully fair comparisons between the intellectual works of different periods. Those of the later period have stood on the shoulders of earlier giants; those of the earlier period have the advantage of veneration.

But to say that Athens outshines continents, and by implication Plato was a thousand times smarter or a thousand times more productive than the best Australian philosopher or scientist, is absurd on its face. Was Plato's head a thousand times larger, did he work for a thousand times longer each day, was he a thousand times better educated, did he have a thousand times better equipment? Of course not-- if anything, every advantage is with the Australian, except the advantage of unexplored territory. Are the plays of Euripides and Aristophanes really better than the movies of Peter Jackson, Russell Crowe, or Nicole Kidman? It is doubtful that they have been more commercially successful worldwide, even on an inflation-adjusted basis.

[Richard Mason]

Posner: Furthermore, technological growth currently favors destructive over beneficial technologies.

I don't think that's clear either. For at least forty years, the indiscriminate slaughter of hundreds of millions of people has been technologically possible. In those forty years there have been considerable beneficial technological advances, but the scale of possible destruction has not really become worse. The trend in military technology for forty years has not been to make weapons more destructive, but to make them more discriminating and more likely to strike their intended target: arguably a positive trend.

[Milk for Free]

A couple of thoughts.

On externalities including global warming: The Nobel Laureate Paul Crutzen has proposed disseminating sulfur particles in the stratosphere as a means of counteracting global warming. The cooling effect of particulate matter in the upper atmosphere has been noted in conjunction with large volcanic eruptions, including the eruption of Mount Tambora in 1815 which dropped temperatures enough that 1816 was known in Europe as the "Year Without a Summer." Dr. Crutzen's idea received some support, if I recall, from scientists at one of the national laboratories, but it hasn't seemed to catch hold among those concerned about global warming. I suspect this is for the moralistic reason that it would allow us to escape the consequences of our profligacy without making lifestyle changes.

On food production: I have to imagine that political opposition togenetically modified crops would lessen in the event of widespread famine. Some of the GM varieties in the works are designed to require significantly less water than their unmodified forebears, and would presumably increase third world crop yields considerably (whereas first world GM efforts trend toward resistance to herbicides or natural pests)

Finally, even accepting that increased innovation would be bad if it resulted in the development of more destructive weaponry, I think it's worth pointing out that nearly all of the innovation in destructive technologies in the past 100 years has come from the United States and Europe, neither of which looks to be a center of future population growth. Most of the growth will be in developing countries that lack the requisite high-tech industry.

[Ben Kalt]

Dr. Becker summarily dismisses economists "demographic transition" argument by saying that not all nations experience significant economic growth. This is extremely obvious, but he seems to suggest that we should accept this fact, throw our hands up and say "oh well." Overpopulation is a real problem but we already know the solution: Foment prosperity everywhere and birthrates will decline everywhere. It is not easy, but poor countries have developed. It can be done. Dr. Becker goes on to say that even declining birth rates do not tend to make the rate of population growth zero or negative (except for in Japan and Europe). That is simply not true. Dr. Becker forgot Korea, Australia, Sri Lanka, Vietnam, Kazakhstan, Cuba, Singapore, Canada, Trinidad and Tobago and dozens of other countries. There are over 60 countries with birthrates below replacement level. Economic growth, among other things, DOES tend to make populations stop growing and eventually start shrinking.
Birthrates>>>>>>http://www.studentsoftheworld.info/infopays/rank/fecondite2.html
The US is the only developed nation that still has a birthrate at replacement levels and the US is uniquely massive and uniquely socially darwinist compared to any other developed country. So development is the answer. The US South, in many ways is an underdeveloped nation within the US, and without it, the US would fit the demographic transition model. So development everywhere is the only viable solution to overpopulation and legitimizing international institutions, like the UN, is the only way to tackle an issue of this scope.

[lammert]

Population saturation curves of bacteria on agar plates provide a quantative illustration of rate limiting available substrate. Equity valuation patterns provide an illustrative quantitive picture of macroeconomic saturation curves where the substrate is a more complex mixture of asset supply, over valuation, debt load, debt and money creation, and ongoing wages. All complex systems have an inherent natural feedback characteristic. Overwhelming Debt Load And The X/2.5X/2.5X Quantum Fractal Natural Law
of Macroeconomic Investment Valuations - How the Macroeconomy Works

[ben]

1. Why does Posner’s first ignore the role of trade in locating efficient production? This seems a large and obvious oversight.

2. True, more population means more Stalins etc., but innovations, in particular the mass media, the internet and its decentralisation of communication, and the related spread of democracy, have sharply reduced the likelihood these monsters will be able to repeat their murder on the scale seen last century. Moreover, living standards are increasing suggesting beneficial innovations are outweighing costs.

3. In his point 5, Posner talks about increasing numbers of Muslims imposing negative externalities on non-Muslims. It isn’t clear to me why Muslims impose a negative externality overall, or why the size of the externality is a function of relative numbers. And why pick Muslims as a collection as opposed to, say, left handers (or whatever).

4. The problem at hand is again viewed by Posner through the lens of global warming, a recurrent theme in his recent posts. Although there is undoubtedly a relationship between warming and population, what about all the other externalities population can produce? Why select global warming as a target for concern in favour of other sources of human misery also affected by population, such as war, or famine.

5. Posner ignores almost entirely the role of institutions, but surely institutions, or the lack of them, and not numbers of people is what defines overpopulation. Posner recently dismissed any comparison of New York with Africa in defining overpopulation, but the reason Manhattan can support so many people is because of advanced and stable property rights, laws and trading. Where is this in his post.

[Bill]

It isn’t clear to me why Muslims impose a negative externality
-from Above

I’d recommend that you read the religious texts of Islam. While both the Old Testament and the Qu’ran refer to violence, the Bible’s references were for limited times (ex. Deuteronomy 12) and that violence is largely denounced in the New Testament.

The Qu’ran is different. Its Prophet, who is known by Believers as the perfect man, directs his followers to act in a warlike fashion against Infidels. Here are three examples from the Qu’ran out of over a hundred:

O believers, take not Jews and Christians as friends; they are friends of each other. Those of you who make them his friends is one of them. God does not guide an unjust people. - 5:54

O Prophet! Exhort the believers to fight. If there are 20 steadfast men among you, they shall vanquish 200; and if there are a hundred, they shall rout a thousand unbelievers, for they are devoid of understanding. - 8:65

When the sacred months are over, slay the idolaters wherever you find them. Arrest them, besiege them, and lie in ambush everywhere for them. - 9:5

People who speak out against Islam (gulp) face a harsh fate:

The punishment of those who wage war against Allah and His apostle and strive to make mischief in the land is only this, that they should be murdered or crucified or their hands and their feet should be cut off on opposite sides or they should be imprisoned; this shall be as a disgrace for them in this world, and in the hereafter they shall have a grievous chastisement, -5.33

These are the things that are taught in the Madrasses syllable for syllable in Arabic, even to students who don’t speak Arabic. Syllable for syllable. If only 10% of a Muslim population numbering in the millions supports violent Jihad (10% was the percentage of British Muslims polled who admitted support for the 7/7 bombings), I think that a negative externality can be properly assumed.

[ali]

i can hardly belive that what is written about muslims by ben is fair.
its important that what actualy is written in Quran but its more important how to interpret and infer the final aim and porpuse of it.
muslims has always been advised to peacefuly live beside other belivers of other faiths and are asked to respect other's thoughts and religions although they themselves do not belive in it.
and one more thing is that Jihad has a trimendous diffrent meaning in islam than what Ben claims based on his violentish! interpretation.

[ali]

i can hardly belive that what is written about muslims by ben is fair.
its important that what actualy is written in Quran but its more important how to interpret and infer the final aim and porpuse of it.
muslims has always been advised to peacefuly live beside other belivers of other faiths and are asked to respect other's thoughts and religions although they themselves do not belive in it.
and one more thing is that Jihad has a trimendous diffrent meaning in islam than what Ben claims based on his violentish! interpretation.

[Haris]

Hey, this is an economics blog! Leave holy books out of this. Or at least include a fair description of whatever you do cite. Pretty sure you're missing a number of instructions to people not to bother Christians or Jews, for they are "people of the book." Not to mention, the most often ignored order in the Qu'ran, namely that there "shall be no coercion in matters of faith." Throw in the frequent reminders to obey rules of engagement and the outlawing of suicide, and the scriptural support for fanatical terrorism is pretty poor. But I will definitely agree that terrorism, and all forms of violence, have terrible negative externalities, to put it mildly.

That said, given Judge Posner's formulation of power in the political arena, obviously a rise in one population lowers the relative power of another. However, I don't think population size matters much these days in the political arena; no one's going to attack Austria even if Austria's population shrinks by a couple of million. Economic might is also hardly related to size anymore, so I don't think population growth in any group really hurts any other.

[AC]

Just because the problem of overpopulation has been exaggerated in the past doesn't mean it is not a problem today. The future may not resemble the past.

The only rational way to evaluate predictions about the future is to look at the predictor's past track record.

An economy (defined to include environmental quality) over time is dynamic and incredibly complicated. There is no way to predict the effect of one input -- here, population growth -- particularly where an economy has the capacity to react or adapt to that input.

How can I prove these statements? I can't. But any assertions about the state of affairs in the distant future are unfalsifiable. I can criticize Judge Posner's analysis, or the analysis of Ehrlich, but no amount of criticism can disprove a prediction that overpopulation will be harmful in the long run. After all, the prediction may prove correct.

Because such predictions are unfalsifiable, the only way to evaluate them is to consider the accuracy of previous predictions using the same methodology. If these predictions have been wrong 50% of the time (or more than 50% of the time in Ehrlich's case), this is the best evidence we'll have that the methodology is worthless.

An analogy. If I have a friend who says he has a system for predicting the winners of football games, I can criticize his system -- he doesn't account for home-field advantage, or injuries, or whatever. Or I can see how he does relative to the expected outcomes, as determined by published spreads. If on average he scores about 50%, then I can conclude his system isn't a useful predictor.

If noone has been able to develop a reliable system, despite many tries, it is more rational for me to act as if there is no such system, rather than change my behavior based on the next prophet's predictions.

It's harder to evaluate methodologies for making long-term predictions than systems for predicting the winners of football games. There are fewer data points. This is where Ehrlich's useful. He's been making predictions for so many years, it's possible to evaluate his track record. He's been wrong time after time. Maybe his current predictions will prove correct. It will be an accident, though. Enough other long-term predictions have proven wrong that I'm skeptical that such predictions are possible. I'm therefore skeptical of Judge Posner's (which, to be fair, aren't really predictions, but are more an accounting of likely costs and benefits).

One other point. Long-term predictions are cheap to make, measured by potential reputational harm. I think the Judge made that point himself in his writing on public intellectuals. This is another reason to discount them.

[ben]

Ali, I think you misunderstand my post. I am on your side in this.

[ben]

Bill,

Its one thing to point out some downsides to more Muslims. Its another to say those costs outweigh other benefits. It isn't obvious to me why costs are likely to exceed the likely large benefits.

Also, it isn't obvious to me why the relative population of Muslims vs non-Muslims is what matters.

[Chairman Mao]

Judge P,

If “an increase in the rate of innovation in one nation benefits other nations” then does an increase in the Muslim population foster more innovation (along with possible ‘monsters’) in Islamic states as they become more powerful? Would Europe ultimately be better off? Is there a direct correlation between power and innovation?

If immigration is curtailed and the birth rate in the immigrant producing countries remains static, wouldn’t poverty in those countries lead to famine and wars thus reducing the population or otherwise force governments to pass laws such as China’s ‘one-child’ policy?

“The increasing lethality and availability of weapons of mass destruction--the proliferation problem--has a greater short-term downside…..”

Do you have any evidence of this? Apart from increasing the negotiating/defensive power of the new nuclear powers and providing them with a sense of security, is there any reason to believe that such weapons will ever be used in an offensive manner? Doing so would certainly be suicide for that nation and its government. Nukes may have an upside of providing more stability.

[Dan C]

A fuller analysis would require that Judge Posner look at the impact of declining populations on various nations and the world. The LA Times recently did a thumb sucker on the Vanishing Russians.

http://www.latimes.com/news/nationworld/la-fg-sickrussia.storygallery,0,196062.storygallery

For example, declining populations and reduced opportunities have forced Russians in some areas to live in very toxic environment, because they have no other options. i.e. reducing population will not automatically lead to less pollution.

The problem with the increasing Muslim population is that their home countries are unable to produce enough economic growth to deal with their growing population. This has led to more radical views taking hold. Young men who feel the need to blame others, outsiders, for their limited prospects led to problems in Japan and Germany before WW 2, and in Muslim countries today.

Muslims who migrate to Europe are often hostile to their new countries (see French riots etc). While China and India are moving toward free markets, it isn't as clear what direction the growing Muslim population will take Europe. The corruption in most Middle Eastern (and African) countries is hardly a model for economic growth or civil liberties.

In short, a Muslim dominated Europe could be a second Dark Ages with limited or no economic growth. Also many, if not most, Muslim have stronger ties to religion then nation. How will that impact the future?

In any case, I would not try to bribe other countries to reduce their birth rates. Most countries, as they grow economically, create their own brakes on births.
A fuller analysis would require that Judge Posner look at the impact of declining populations on various nations and the world. The LA Times recently did a thumb sucker on the Vanishing Russians.

http://www.latimes.com/news/nationworld/la-fg-sickrussia.storygallery,0,196062.storygallery

For example, declining populations and reduced opportunities have forced Russians in some areas to live in very toxic environment, because they have no other options. i.e. reducing population will not automatically lead to less pollution.

The problem with the increasing Muslim population is that their home countries are unable to produce enough economic growth to deal with their growing population. This has led to more radical views taking hold. Young men who feel the need to blame others, outsiders, for their limited prospects led to problems in Japan and Germany before WW 2, and in Muslim countries today.

Muslims who migrate to Europe are often hostile to their new countries (see French riots etc). While China and India are moving toward free markets, it isn't as clear what direction the growing Muslim population will take Europe. The corruption in most Middle Eastern (and African) countries is hardly a model for economic growth or civil liberties.

In short, a Muslim dominated Europe could be a second Dark Ages with limited or no economic growth. Also many, if not most, Muslim have stronger ties to religion then nation. How will that impact the future?

In any case, I would not try to bribe other countries to reduce their birth rates. Most countries, as they grow economically, create their own brakes on births.

Muslim countries would most likely reject such aid from the west. African nations could support larger populations of productive adults except that failed political systems and disease prevent that from happening.

I would work on increased trade, investment, and opportunity. As a child demands more resources from a family, whether from opportunity cost or direct expense, we will see fewer children in the world. But it will be a better, less convolutedly regulated, world

[Dan C]

I am very sorry. The cut and paste job on my previous post was poorly done. This is a cleaner post.

A fuller analysis would require that Judge Posner look at the impact of declining populations on various nations and the world. The LA Times recently did a thumb sucker on the Vanishing Russians.

http://www.latimes.com/news/nationworld/la-fg-sickrussia.storygallery,0,196062.storygallery

For example, declining populations and reduced opportunities have forced Russians in some areas to live in very toxic environment, because they have no other options. i.e. reducing population will not automatically lead to less pollution.

The problem with the increasing Muslim population is that their home countries are unable to produce enough economic growth to deal with their growing population. This has led to more radical views taking hold. Young men who feel the need to blame others, outsiders, for their limited prospects led to problems in Japan and Germany before WW 2, and in Muslim countries today.

Muslims who migrate to Europe are often hostile to their new countries (see French riots etc). While China and India are moving toward free markets, it isn't as clear what direction the growing Muslim population will take Europe. The corruption in most Middle Eastern (and African) countries is hardly a model for economic growth or civil liberties.

In short, a Muslim dominated Europe could be a second Dark Ages with limited or no economic growth. Also many, if not most, Muslim have stronger ties to religion then nation. How will that impact the future?

In any case, I would not try to bribe other countries to reduce their birth rates. Most countries, as they grow economically, create their own brakes on births.

Muslim countries would most likely reject such aid from the west. African nations could support larger populations of productive adults except that failed political systems and disease prevent that from happening.

I would work on increased trade, investment, and opportunity. As a child demands more resources from a family, whether from opportunity cost or direct expense, we will see fewer children in the world. But it will be a better, less convolutedly regulated, world

[James]

"... The increase in the world's Muslim population is a negative externality for non-Muslim nations, especially the European nations, with their shrinking or about-to-start-shrinking populations. But by the same token an increase in the non-Muslim population of Europe would probably be a boon for the European nations. ..."

I tend to agree, but could Judge Posner put forward his reasons for this view, and also let us know if the same applies in reverse?

[Basil Go]

Basil Jason Go
Metro Manila, Philippines

More Furious than a Forest Fire
People who have read population control articles have probably heard of the English economist Thomas Malthus who proposed that population increases at a geometric rate whereas food supply grows at an arithmetic rate if factors are held constant. Probably, Malthus’ Principle of Population is not so improbable after all when studies show that approximately 790 million people in the developing world are still chronically undernourished, almost two-thirds of whom reside in Asia and the Pacific.
In the Philippines, due to the Church’ heavy opposition against artificial birth-control methods and the masses’ lack of sex education, the problem of overpopulation continues to persist. What makes matters worse is that the natural family planning methods are somewhat hard to instill in the minds of the Filipinos especially those that are not so educated. What solution do I propose then? I believe that the government should start implementing a policy similar to that of China’s one-child per family. I repeat similar and not exactly, since what right do we have to impose how many children a couple would want to have? Hence, I am not saying that the government should immediately implement the one-child per family policy here. I think it would be best if the Filipino community would first agree upon a consensus on the number of children they would want to have.
In line with this, the current tax system in the Philippines of giving a tax exemption of P8,000 per dependent child not exceeding four seems not to be very effective since there are a lot of people still have more than four children. Instead, I think it would be better if from the agreed upon number, the government can give more incentives to those who follow the quota. Given this, it would be more attractive for the people, especially the masses, to have lesser children. For instance, if the set quota of children is four and the family only has two children, then there should be an additional incentive for this family. Unlike China’s one-child policy, I believe that there should be no penalty if a couple exceeds the quota since the couple has the right to have as many children as they want. Although this entails a lot of discipline for those who will implement it, I believe that this a step in the right direction for curbing the population growth in the Philippines.
Currently, the Philippine population is around 89 million, growing at a rate of 1.8 percent. In ten years, the population will reach 107 million, an increase of about 20 percent. Clearly, the figures speak for themselves. With the present population growth rate, the supply of resources such as food, shelter and clothing won’t be able to meet demand. Population growth is like a forest fire, we have to do something about it now. If we don’t, when is the right time?

[AC]

"Population growth is like a forest fire, we have to do something about it now."

A good specimen for any collector of doomsday predicitons.

At least Basil does not advocate coercion backed by violence, like some of the more wild-eyed prophets.

[Jose Costa]

"The relationship between aggregate population and creativity seems in any event very loose" of course, Estonia is a tiny eurpoean country and is now seen as Europe's next Ireland or Silicon Valley.

I believe it's all about poverty. If overpopulation is a problem to the U.S, in Europe aging population and low birth rate are threatening the future. Parts of Asia and Africa are overpopulated, so we can call this "demographic disequilibrium".

Emigration is an escape from bad living conditions, so if ending poverty rises into world's top concern, We shall no longer see people betting their lives to cross the atlantic in small boats from Senegal to Spanish Canary Islands.

[Paco Guerra]

In a previous blog, Becker proposed the taxing of fat as a possible solution to the problem of obesity. Few economists, however, have considered a direct tax on childbirths. Yet, if overpopulation is the cause of so many externalities, then a tax on childbirths should not, in principle, be dismissed out of hand. Of course, an alternate solution is 'direct regulation', such as the one-child policy in China. Nevertheless, I prefer the tax method over direct regulation since the former is generally less intrusive and more flexible than the latter.

(I understand that I am ignoring certain Kantian or moral objections that might be raised against any interference with 'reproductive autonomy', but these same objections could be raised against any restriction on individual liberty, such as compulsory vaccinations, etc., and so are of little practical value.)

[N.E.Hatfield]

Ever since we started out as furry little balls running through the grass of the Savannah, one thing has held constant, " Necessity is the mother of invention". It has carried us through the Stone Age, Bronze Age, Iron Age, Plastics Age and on into the Post-Industrial Age. During all this time the population has continually grown. If we lose that relationship between Necessity and Invention we are doomed and will fall foul of the Law of Natural Wildlife Management and Control known as Environmental Maximum Population Carrying capacity. Or we could end up as the lab rats do in every Behaivoral lab study on population. At each others throats. But even in this case, Necessity has been the mother of invention (socio-political in this case). At least for Homo Sapiens.