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Nancy Swaim

RE: Population growth

How do you disagree with Ben Wattenberg's work on population grown?

Rue De Quatre Vents

Judge Posner writes:

The New Orleans flood may be the first disaster to which global warming has contributed; it is unlikely to be the last.

How is this the first disaster to which global warming has contributed? What clearly marks this inauguration? There have been three category 5 land-falling hurricanes in the last 36 years, which triples the number in the previous 118 years. Perhaps this might indicate that global warming has exacerbated the conditions necessary for generating hurricanes of this magnitude. Still, such reasoning would not warrant calling Katrrina or the consequent flooding as the first disaster due to global warming. Why not the tsunami? Why not hurricane Andrew?

Given this comment, and the general tone of his post, I fear Judge Posner might be slipping, albeit slowly, into the role of a reverse Dr. Pangloss.

michael persoon

I think that Posner hit onto part of what is essential to the "sustainable growth" movement when he pointed to the fact that as long as population grows faster than utility falls, total well-being is maximized. While this may make that a tenable (even desirable) outcome under an "economic" (utilitarian) analysis, the sustainable growth proponent would find it undesirable because she is concerned not only with production, but distribution over population and over time.

Central Banks and other authorities implement sustainable growth policies already. One example would be intervening to prevent the hot money cycles that caused such ruin in Asia and Argentina. Another would be raising the prime rate to slow borrowing/spending/inflation. Policies such as these, even when operating via market principles, are pointed towards slowing economic growth in order to prevent our economic engines from red-lining and overheating.

Sorry if this post is not a model post, but I think that is a product of the fact that even proponents of sustainable growth do not have a clear view of what that means or what policies ned to be crafted to serve it. Hopefully other posts will help flesh this out.

Aaron Chalfin

Posner writes: "The combination of increased longevity as a result of medical advances and healthier life styles, reduced infant mortality, and a continued high demand for large families in much of the world seems likely to overcome the "demographic transition," that is, the well-documented negative effect on birth rates of increases in average income to middle-class levels."

However, past experience tells a different story. Rather than increasing population, over the long run, a rising standard of living decreases population growth as it changes the preference for a large family and leads families to substitute "quality" for "quantity" in raising children. Posner notes this effect but he continues to worry that it will be dwarfed by the decline in death rates.

Sure, in the short-run, advances in medical technology might cause a mini population explosion. But I think Posner is underestimating the impact of the demographic transition. Preferences will change. Improved health and wealth means that children are no longer needed for agricultural labor or as a form of old-age insurance, and as women increasingly become educated, the supply of children/the demand for children will fall precipitously. Additionally, increased educational opportunities and increased modes of consumption raise the opportunity cost to having children.

In the U.S. birthrates declined from 30.1 per 1000 in 1910 to 14.7 per 1000 in 2000 (http://www.infoplease.com/ipa/A0005067.html). A birthrate of 14.7 has been consistant with virtually zero population growth. And the US in 1910 was not nearly as poor as the third world is today. As such, we can expect even larger declines. The long run equilibrium may, in fact, be declining rather than growing population.

I do think that the demographic explosions occuring in certain areas of the world pose a problem for stability over the next half century. But I strongly disagree that improved healthcare and wealth renders future growth unsustainable.

Patrick R. Sullivan

According to Patrick Michaels


we're just returning to hurricane cycles seen in the 40s-60s. See his color graphs at the above site.

Paul N

Yes, life will change as population grows: the air will be hotter, humans will be more densely packed, etc. But adapting to increased population is the very nature of the modern human species. I don't think Posner presents a compelling case for why upcoming population growth should be, on average, harmful for us, while every previous growth (e.g. agricultural revolution, industrial revolution) has been a boon to both per-capita and total utility.

And I don't think the average "Third World" life is as miserable as Posner imagines it to be.

Seth Ayarza

With regards to the population growth concern, I do not think Genius output as a result of increases in population is a zero-sum game(as canceled out by evil counterparts). While I agree that a 1 benign geniuses good is outweighed by 1 evil geniuses harm, there is nothing to indicate that they have similar rates of occurence in society.

In fact, sociopathic geniuses are extremely rare flukes in society. They are the unfortunate result of dual exceptionalities occuring at the same time in a single individual, a probablity at least (at least) 100x rarer then either of these components registering individually. Thus we might expect 100 Luke Skywalkers for every Darth Vader out there.

However, I must concede that the net positive effect of a benign genius isn't assured(some I'm sure some end up working behind the counter at blockbuster), while in contrast evil geniuses have practically certain net negative effects.(thats what makes them evil afterall!)

A further concession: A concern regarding humanities 'planetlocked' residency of a couple million square miles of land on earth.

One could imagine a critical mass of 'evil geniuses' paired with powerful technology in which the extinction of mankind was a probable outcome.
(X size of population)->(Y#evil geniuses)->(Blow up Z(acres of land)--->(Earth Goes Boom)

I see no better argument for tripling NASAs funding.


This all seems to be a variation argument on the "Law of Thermodynamic Entropy". For those not familiar with Thermo, essentially, "things run down" and inevitablly will, provided that there is nothing to jump start the system. As in all the socio-economic modeling that has gone on before is all based on these thermodynamic principles as the Economists would put it "Ceteris Paribus".

But there is another fundamental rule at play in human history and development and that is, "necessity is the mother of invention". Is the human mind and the ability to adapt to new situations a truly anti-entropic principle? If so, the future may be brighter than is imagined, although it may be radically different.

Lee Beck

If geniuses play such an important role in your calculation, then the truly fateful years are soon coming with the genetic engineering of humans. Every parent will want the highest intelligence for their child relative to others. The percentage of geniuses will rise and the externality will be increased world volatility --- much faster than in the constant-percentage scenario you describe.

More generally, as prices fall and geniuses rise, the ability to influence the world will devolve from states to individuals. More and more people who have no accountability will have their fingers on the "red button," so to speak. Terrorism is maybe our first taste of this.

So I am pessimistic too.

Sylvain Galineau

No need to resort to future geniuses and assorted hopes and prayers.

World population has increased by about 1.6bn between 1980 and 2000, yet both the absolute and relative number of starving individuals have decreased over the same period. Most of Africa and large parts of Asia still farm their land with low-yielding technology and seeds. India's green revolution has proven beyond any doubt that very large populations can be fed and grow without necessarily clearing a proportional amount of additional land for farming.

michael persoon


I agree with you, but I think that the ability to feed people is a very low baseline for a measure of quality of life. Posner pointed to the effects that population growth (worldwide) will have on the consumption of goods and the associated output of pollution. A whole new class of consumer is rising in China and they are going to be concerned with a lot more than having enough food. This, coupled with increase in life expectancy, is the problem.

This is one of the points of critique that I think "sustainable growth" proponents bring to bear on growth-driven capitalism--ever more "efficient" allocation of resources leads to more efficient and widespread consumption. I think they are suggesting that policies must be implemented to slow this down, and to not value efficeint production and growth over all else. Is "sustainable" the oppostie of "growth?" I am not sure, but they seem to be at odds at lest in part.


Posner raises a few points that Becker seems to elide over in his optimism. First, with increased population growth, we as humans will be producing more carbon dioxide emissions contributing to at least ozone layer depletion (I'd rather not get into when and how the greenhouse effect is affecting us). Furthermore, we could end up with lower levels of utility as medical costs take up the bulk of our income. These 2 points underscore what I think is fundamentally important about the impact of negative externalities to the future of development. First, we will run out of air before we ever run out of oil. There is still no effective mechanism for for regulating the pollution of the environment. The Kyoto Protocol for example only treats carbon dioxide emissions but not methane gas, which Europe is so fond of using (not to mention the U.S. and China haven't signed Kyoto anyway). Still worse, the very real problem of medical costs looms over us more than any problem that social security could cause. With increased technology in medicine, people will live longer, but that also means it will cost more to live longer. I see this leading to a greater problem of redistribution since more than anything this type of care will most likely be available to the rich first. Both on negative externalities and higher life expectancy lead to serious problems to "sustainable growth" since many people may not be able to gain the same benefits as groups from before.


There is always a problem with over-population, we all agree on that. If everyone starts reproducing like mad then the most rational solution is to go to war. People adapt by becoming cruel, they love their own lives and so they say, 'most people don't deserve to live at all.'(hey, we're not that pessimistic) Currently, in a country like America where children are stigmatized because you need to make at least $100,000 to really 'mildly adequately' support two bright children, then the poor shouldn't give birth at all.

What's terrible about the 'no children' slogan is that most people stop caring if they're not investing. If they have no children to take pride in, why would it not be rational to rob a store? Why would it matter if they're lonely, if they're depressed. When something disturbs the balance then social forces create a new way to affirm order. When elites talk down on the people and complain about overpopulation then sterilize the 'inferior stock' the inferior stock has absolutely no reason at all to conform. No reason at all to follow orders, the elite are not aristocrats, they are not created aristocrats, they have to earn it day by day.

If they fail in that, there is always the possibility of replacement. Its an obligation.

Besides, when people love their children they stop depriving their children by having too many children to care for. People are becoming more sensitive.(when they stop being overly-pessimistic, a la Malthus)


"Posner raises a few points that Becker seems to elide over in his optimism. First, with increased population growth, we as humans will be producing more carbon dioxide emissions contributing to at least ozone layer depletion (I'd rather not get into when and how the greenhouse effect is affecting us)."

CO2 does not deplete the ozone layer (CFCs do), and ozone depletion is unrelated to global warming to my knowledge.

" First, we will run out of air before we ever run out of oil."


"There is still no effective mechanism for for regulating the pollution of the environment."

How do you explain the reduction in air and water pollution since the 1970s, then?


What's with the unguarded optimism about nuclear? The reduction in CO2 emissions is wonderful, but there are some hard long-term questions -- even without assuming any evil geniuses at all.


Of course, Posner's post is entirely speculative. The alarmist fear of overpopulation has been raised in the past and has never proven to be grounded in fact. World overpopulation is not really a problem; the earth can sustain far more humans than currently inhabit it. However, overpopulation in certain areas, particularly poor, underdeveloped countries, can depress the standard of living for all. In areas where overpopulation is a problem, governments would be well advised to promote family planning and encourage the use of birth control. Unfortunately, some governments are too blinded by religious taboos to encourage the use of birth control.

I do not by any means think that China's one-child policy represents a model program. But it is an example of how family planning, encouraged by the state, can help a poor country become richer.

Posner raises good points about greenhouse gas emissions and energy sources (that is, the price of oil). Obviously, the world has to move beyond oil, and our gov't should take the lead in promoting conservation and developing new ways to produce energy. Unfortunately, we seem to be ruled by the oil execs. Little changes can make a big difference in the short term, such as hybrid cars and energy-efficient homes with networked solar panels. Bigger advances, such as fusion, are down the road. Humans are an adaptive species, and we will adapt to the lack of oil. But it will be a smoother transition if we develop the new technologies before the oil shortage becomes a crisis.

Likewise, with global warming, we need innovative ideas to reduce emissions. The U.S. was stupid to spurn Kyoto; even if it wasn't the best treaty, it was a good start. We have now lost several years in the battle, which will have to be regained. Once again, short-sighted gov't run by vested interests is the problem. We need to be forward looking on this.


The U.S. was stupid to spurn Kyoto; even if it wasn't the best treaty, it was a good start. We have now lost several years in the battle, which will have to be regained.

Precisely the opposite conclusion holds if you recognize that a) agreements that do more for the environment will be delayed for as long as Kyoto is in force, and b) Kyoto, with its reliance on bright line targets and large international transfers, is unlikely to do much if anything for the environment in view of real world political constraints. The biggest net polluters are unlikely to sign up to, or remain with such a system.

I believe the US, if by accident, did the environment a favor by pulling out of Kyoto. The sooner that Kyoto dies the sooner effective environmental policy can begin.


This all seems rather reminescent of a basic rule of Wildlife Management. Which states, that in any ecosystem there is a maximum "carrying capacity" that a system can maintain over time before a population crash occurs. And so, in order to maintain that maximum level, some form of population controls need to be put into effect. A form of "wildlife management" if you will.

Nature accomplishes this through epidemics, famines, war, pogroms and the like. It's only a matter of time before nature imposes its control mechanisms. Unless of course, we can outsmart it. We've seem to have been able to do it so far. Only time will tell.

Larry Horse

First off, I need to commend asaa for that brilliant comment.

If one assumes that income is a good measure of intelligence (I guess Becker would be able to address that issue better than any of us here, and probably better than anyone in the world), and people have less children as income rises, and we also assume that intelligence is largely genetic, then is there the possibility that if we get to a point where geniuses are only having 1 or 2 children per couple, that there will be a steady state of geniuses, while people of non-genius intellect primarily fuel the population growth, and thus we do not have a commensurate larger number of geniuses as the population rises?

Beyond that, I really don't know what to think about population growth. In the past population growth has not gotten in the way of improving qualities of life, as humans do adapt since markets create incentives for people to develop methods that allow more people to live off of the same planet. However, I think that people like Wattenberg are incorrect in worrying that population decline over time is bad for the world for the same reasons: as the population ages, humans will develop means to make those able to work more productive so that they can feed themselves, their parents, and their grandparents with the shrinking total amount of labor.


I am shocked by Posner's views on global warming. This position is completely out of step with the analysis I have come to expect from him. The science behind global warming is disputed, and the nature of global warming and its effects are the subject of ongoing scientific investigation. While it may be reasonable to hedge our bets ahead of time in case the science ultimately demonstrates a genuine threat from human-driven climate change, Posner's comment implies that he has already concluded that global warming is a definite threat which he takes "very seriously".

Furthermore, his comment that "The New Orleans flood may be the first disaster to which global warming has contributed; it is unlikely to be the last." establishes Posner's conviction that not only does global warming exist and not only does global warming pose a threat (both controversial propositions for those who follow the science), but in addition Hurricane Katrina was caused by or worsened by global warming. This is speculation stated as if it were fact. Good judgment means a person must realize the limits of what he knows and refrain from giving speculation and assumptions equal standing with solid science. While the good money in the scientific community might be on global warming, the collective speculation of the scientific community has been wrong on countless occasions in the past.

Population concerns are likewise misplaced. I expect such comments from the likes of Malthus and Ehrlich, but never Posner. Wealth is the ultimate in birth control. Without fail, fertility in wealthy countries declines as economic opportunities compete with child bearing and rearing. There is no reason to believe that things will be any different in what are currently 3rd world countries if and when they attain sufficient wealth.

The genius argument is a canard. While geniuses certainly might contribute far more than the average person to the betterment of mankind, they are so rare that their overall impact is not particularly significant. Human development would progress at roughly the same pace without any geniuses at all.

One concern I share with Posner is his view on the elderly. The non-productive population in the US is going to grow substantially. Pressure to increase welfare spending to at the very least maintain current levels of benefits might result in a larger welfare state that faces economic difficulties not unlike those faced by some European nations today. Problems like these have ways of working themselves out. The elderly, although powerful now, will still be in the minority. Once the much more numerous voting productive majority is faced with substantial impairments to their quality of life to support the poor individuals among the elderly, at some point the majority will vote to protect itself and curtail the welfare state. Wealthy retirees will benefit from more and more medical advances while poor elderly individuals will ultimately live better than they do now, but nowhere near as well as the wealthy. Politically, liberals will try to counteract this and conservatives will battle them. This battle has endured for much of this nation's history and here we are. I don't doubt this nation will ultimately resolve the problem when the time comes, as it has resolved other seemingly insurmountable problems in the past.


As the old saw goes, "figgers don't lie, but liars sure can figger!" ;) Perhaps we ought to look up the statistical tables at NOAA on number and strength of hurricanes by decade. I think the greatest decade was from 1940 to 1950. This decade isn't even a close runnerup. So much for global warming as a primary cause, that is, if you believe in statistics.


I have admired Posner's thoughts expressed on this blog for a while now but I have to say that I think he has finally dropped the ball in this week's comment. Even the most rational individuals have their blind spots (for Richard Dawkins it is George W. Bush) and perhaps for Posner it is environmentalism and sustainability.

I think Posner's comment has two major weaknesses. He writes, "[t]he higher the price of coal, oil, and natural gas, the better, as far I am concerned." Later, using unusually emotive language, he speaks of an "ominous reduction in biodiversity". These, I think, imply a concern with environmental welfare to the exclusion of human welfare (where human welfare is defined to include environmental factors as one, but only one, of many drivers of human happiness). Posner's statement implies a focus on environmental welfare because higher energy prices without limit is almost certainly not in the interests of human welfare, unless of course the only thing we care about is the environment (which is not true). Perhaps Posner did not mean to go quite so far in his comment. But if he really believes in saving the environment even at the expense of human welfare then he has essentially deified nature and his comments should be seen as being made from a religious perspective not a reasoned one.

A second weakness in Posner's comment arises from his concern for population growth. Posner speculates on the sorts of ways additional population growth could impose costs which outweigh benefits from advances in technology. The problem with fearing population growth is that an awful lot of it has occurred in the last 100 years, which has produced all of the things that Posner worries about (including a larger retired population) yet here we are with higher average living standards than ever. We are left to speculate why the next 100 years of growth will produce such contrasting outcomes in Posner's view, yet this is crucial to understanding his pessimism and seems an obvious oversight.

Perhaps Posner will clarify his views in his response.


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