I don’t know how to answer this question. But recent posts by Tyler Cowen, Ross Douthat and Robin Hanson all suggest that the answer is “more”. Here’s the headline of Tyler’s recent article:
What Does the World Need? More Humans
Global depopulation is the looming existential threat that no one is talking about.
The world currently has 7.8 billion people, and that total is expected to rise to 10.9 billion by 2100. The population may begin falling in the 22nd century, but I wonder if it’s a bit early to begin planning for something so far out in the future, which is so hard to predict. Back in 1970, most experts were worried about overpopulation, at a time when the world had less than half as many people as today.
What is the optimal global population? I just completed Schopenauer’s 1200 page magnum opus on philosophy, which argues that the correct answer is zero. At the other extreme, some argue that all human life is wonderful, pointing to the fact that even people living in horrible conditions—say North Korean concentration camps—typically do not commit suicide. Both claims are plausible, but I’m not entirely convinced by either extreme. I remain agnostic on the question.
We could apply the utilitarian criterion that the optimal number of humans is the one that maximizes aggregate global utility (perhaps including animal utility in the calculation.) I have no principled objection to that approach, but I don’t see how to implement it.
People often criticize utilitarianism by pointing to the fact that utility cannot be measured. I accept their point, but still find it to be a useful policy guide for real world public policy decisions. While we cannot measure utility exactly, we can have well informed views that one situation has a higher utility level than another. Thus is seems very plausible that South Korean public policies produce higher utility than North Korean public policies. But when I use utilitarian reasoning I always implicitly hold the population fixed. I find it almost infinitely more difficult to think about utility in an absolute sense. How many Swiss people does it take to have the same total utility as 100 residents of rural Pakistan? I wouldn’t even hazard a guess, and thus would be extremely reluctant to advance any public policy agenda on that basis.
Some population boosters point to polls suggesting that Americans would prefer to have more children. OK, but why don’t they? Presumably there are some barriers related to the resources (time, money, etc.) required to raise children. But then what are the public policy implications? People would also prefer to have more money, bigger houses, more vacations, and lots of other good things. Should public policies subsidize those goods? For children the answer might be yes, as there’s a sort of “positive externality” aspect to raising kids. But that just pushes us back to the optimal population question in the title of this post. What is the answer?
Another possibility is that we should keep population roughly where it is, as change can cause problems. Thus keep Japan’s population at roughly 125 million, Britain at roughly 68 million, and New Zealand at roughly 5 million, even though these three island groups have roughly equal ability to support human life. But I’m not convinced that the disruption caused by Japan gradually declining in population and New Zealand gradually growing in population is all that bad. Yes, you can point to downsides from population aging, but also some upsides (less crime, less traffic congestion, less pollution, more living space.) So I’m not convinced by the claim that while we don’t know the optimal population, surely we know that population decline is bad.
People worry that Europe will turn into a sort of museum. I love museums!
PS. Suppose it turned out that the “correct” utilitarian answer to the question in the post title was that the world should become populated until living standards fell to those of a North Korean concentration camp, because all life is basically wonderful. At that point I suspect Cowen and Douthat would jump ship, but Hanson would stick with the utilitarian logic of the analysis.
PPS. I had always assumed that the Christian religion had a sort of “be fruitful and multiply” ethic, but Schopenauer points out that this is the Old Testament, and argues that the New Testament has a very different perspective. Can anyone confirm?
PPPS. Schopenauer’s The World as Will and Representation is highly recommended for disillusioned people. Optimists might like his book on how to be happy, which is perhaps just as impressive, but in a radically different way.
READER COMMENTS
AJ
Mar 31 2021 at 3:47pm
Hi Scott –
You write:
I criticize utilitarianism because it doesn’t tell you which pleasure or which happiness ought to be chosen. There are simply too many different kinds of enjoyable activities and too many different modes of happiness resulting from different choices and vocations that we can experience for utilitarianism to be of any practical help and are useless to compare. So my thought is that any appeal to it to justify a particular project or purpose is probably nothing but the disguised arbitrary preferences of the person making the appeal.
Swami
Mar 31 2021 at 4:31pm
It seems to me that every human life is precious, and therefore that, all else equal, we should lean toward more humans.
It also seems to me that the preciousness of life is not time sensitive — the life is just as previous to that person a billion years from now as today.
It also seems to me that overpopulation today can both lower average utility today and going forward, and it can also threaten the extinction of humans, thus leading to the non birth of hundreds of billions or trillions of souls. This is a very bad thing.
Thus, the solution is to maximize long term population not necessarily current population. This would suggest that we should optimize around utility today, setting the stage for long term thriving of the human race.
Scott Sumner
Mar 31 2021 at 10:24pm
But those criteria don’t really tell us whether more people would make things better or worse.
Swami
Apr 1 2021 at 6:24pm
More people, all else equal, is better, if life is a precious thing (and i would argue it is). You are right that this doesn’t tell us how many people TODAY is optimal. But it does change the focus from trying to optimize today, to optimizing for the long term future. It shifts the conversation completely to the sustainability of the human race.
Sarah
Apr 2 2021 at 12:53pm
Human life isn’t the only kind of life that matters, though. And the more humans there are, the more other kinds of life, other species, suffer. Facts.
bill
Apr 3 2021 at 9:09am
I like this idea of optimizing for population over the long term. My personal views lead me to worry about things. I’m not concerned about micro depopulation (like Japan). I tend to think a stable to ever-so-slowing declining population is one that minimizes the chance that we do something catastrophic. I’m probably just rationalizing.
John Hall
Mar 31 2021 at 4:38pm
“How many people should the world produce?” is a different question from “How many people should country X produce?” The first has all sorts of interesting potential discussion points, but the second also introduces geopolitical considerations, in that if country X’s population declines, while neighboring country Y’s population increases, then there might be increased risk of invasion. The second question might be a bit more focused as “What percent should country X’s population change relative to the percent change in the global population?”
Kyle Walter
Mar 31 2021 at 5:11pm
I suspect most scholars of Early Christianity would tell you that the authors of the New Testament expected the world to end very quickly, within their own lifetimes (e.g. Matthew 24:34). Hence, reproduction and the long term human future on earth were simply not a big issue. That’s a far-cry from being anti-natalist, though I don’t know if that is the claim Schopenhauer is making. The early Christian church was also uniformly against abortion and contraception.
Scott Sumner
Mar 31 2021 at 10:27pm
I believe he claimed that chastity was encouraged. People who became monks were seen as being more virtuous. I know little about this issue, so I don’t have an opinion as to whether he is correct.
Mactoul
Mar 31 2021 at 10:45pm
Chastity does not equate to celibacy. A married couple having ten children may be perfectly chaste.
Warren Platts
Apr 1 2021 at 9:55am
The Shakers believed in total celibacy. They did not procreate. Needless to say, there are very few left.
Thought experiment: What if all women on Planet Earth decided to go on strike and just stopped having children? Homo sapiens would then go extinct within a century. Would this be a tragedy? Why? After all, there is no coercion, no violence, no pain involved. Only autonomous individuals making autonomous decisions.
robc
Apr 1 2021 at 10:53am
1 Corinthians 7 would probably be the best chapter covering the new testament view. Here is the first 9 verses, bolding is mine:
Scott Sumner
Apr 1 2021 at 3:00pm
Thanks, I think that’s what Schopenauer had in mind.
Mark Z
Mar 31 2021 at 5:23pm
I think a key issue that may be missed here is that it isn’t simply a question of how many people is optimal. Rapid population decline is a problem in its own right for the people who are currently alive. It may be fine to let the population decline to half its current level, but doing so by having 1.9 children per woman for a few generations is probable a less disastrous way to do it than nobody having any children for 40 years.
In any event, I’m not convinced it makes sense to prefer any number of people from a utilitarian perspective. One should want people who already exist to be happier (or those who will inevitably exist in the future to be happier when they arrive). But to think, ‘all those people who don’t exist would be so much happier if they existed, so we should create them’ just seems incoherent to me.
Frank
Mar 31 2021 at 5:31pm
The utilitarian answer is NOT that population should increase until the AVERAGE living standard is at a very low level, but RATHER that the MARGINAL living standard is at a very low level.
Scott Sumner
Mar 31 2021 at 10:28pm
Yes, I understand that. But suppose the optimal was a point whether the average was also quite low. That’s certainly possible.
john hare
Mar 31 2021 at 5:59pm
I’m not real big on telling other people how many kids they should have. Or telling other people what standard of living they should settle for. Certainly there are policies that I think should be implemented, but they mostly relate to me not supporting other peoples kids in perpetuity.
Jerry Brown
Mar 31 2021 at 6:44pm
I try not to think about your question. I have no good answers to it for one thing.
I am probably going to botch this badly because it was a while ago and my memory isn’t that great- but I think Russ Roberts once put this on his podcast in a way that was very wise. It was do you see people as stomachs to feed or as brains that can be useful. Or something like that. Your viewpoint on that is probably going to determine the answer to your question.
But even if you had a strong opinion one way or the other, I think it would be perfectly acceptable to say screw you- mind your own business and don’t tell me how many children I should or shouldn’t have.
Christophe Biocca
Mar 31 2021 at 7:21pm
I’m going to give Tyler the benefit of the doubt here and assume he didn’t pick this byline. The content of the article is certainly not supporting anything close to that apocalyptic conclusion.
I think the biggest “problem” with the demographic shift is a lot of promised benefits to seniors depend on it never actually happening. But trying to keep population growing at 1960-2000 rates just kicks the same problem down the road (with an even bigger population of seniors at risk).
Daniel Hess
Apr 5 2021 at 4:51pm
“I think the biggest “problem” with the demographic shift is a lot of promised benefits to seniors depend on it never actually happening.” But trying to keep population growing at 1960-2000 rates just kicks the same problem down the road (with an even bigger population of seniors at risk).”
It matters terribly which population is growing and which population is collapsing. The population that has been innovative and has been feeding the world’s poor is in the midst of demographic decay.
The population of impoverished poor that has not been innovative and has been fed by the wealthy nations has been soaring.
The dangerous thing in this dynamic is that people can be incredibly productive very late in life and so this hides the problem of a dearth of similar young people. For example, the average age of a US farmer is 57 years old. These incredible farmers make up 1.3% of the population and feed America and the world abundantly. But if there aren’t equally productive people waiting in the wings to take over, the system must break.
Korea has had a number of years of ultra low fertility. But they could go 20 years with zero children and have more productivity and exports than ever before because people aged 0-20 are not productive and are a net drain. The country would be going over a cliff toward total collapse, and yet late in the game its economic numbers would be better than ever before. This is the case with the developed world today.
The productive and innovative part of our world is aging and not being replaced. But output is higher that ever. Interest rates are low even as borrowing soars. Everything looks great, right? But the demographic decay of the innovative and productive portion of the world population must break the back of the economy. Those aging people who had few children cannot go on forever.
Ken P
Mar 31 2021 at 7:35pm
I think this puts the cart before the horse. The prevailing theory is that people have fewer children when they get wealthier – that increasing wealth is driving the decline in population growth.
Lizard Man
Mar 31 2021 at 10:19pm
What do you make of the fact that in some countries, like China, wealthier people in urban areas tend to have more children? Does that imply that at a certain level of affluence, birth rates could start rising again? Or is it too tied into relative affluence and competition for social status (i.e. the wealthy have so much status that they can have kids and be assured that the kids will be high status as well)?
Warren Platts
Apr 1 2021 at 10:05am
It is the same pattern in the USA: The wealthiest quintile have the highest fertility. The problem is people cannot afford to have children anymore. Birth rates fell off the cliff after the 2008 recession. We can expect them to fall even more after this one is over. That is clear sign there are too many workers. As Ricardo pointed out in his magnum opus, a tight labor market is a happy labor market. Conversely, in a slack labor market, Malthusian effects ensue: higher death rates & lower birth rates. Indeed, in one of the China shock papers, in commuter zones affected by import shocks, birth rates declined by 3 or 4X more than the death rates increased.
Scott Sumner
Apr 1 2021 at 3:03pm
You said:
“The problem is people cannot afford to have children anymore.”
This is clearly false. People had many more children when America was much poorer (the 1800s) and today people in poor countries have many more children. It’s more more complicated than not being able to “afford” children.
Mark Bahner
Apr 1 2021 at 5:03pm
In general, it’s pretty well established:
Higher income –> Lower fertility rate
Warren Platts
Apr 1 2021 at 9:05pm
Respectfully, you are both incorrect.
Scott: you are comparing apples to oranges: (a) in the 1800’s, women were considered chattel and did not have access to modern birth control and consequently had little direct say in how many children they had; and (b) what we might call the “natural wage” in those days was much lower than it is now in absolute terms, but it may have afforded numerous children in those days, albeit raised in a squalor that would get parents thrown in prison for child endangerment these days. Ditto for women in poor countries in the 21st century.
The relevant data set is within the USA in this century: (1) birth rates dropped dramatically after the 2008 recession–as clear a case of cause-and-effect as you will ever find in economics; and (2) one of the China shock papers found that commuter zones badly affected by import shocks showed dramatic drops in birthrates compared to commuter zones that were not affected by import shocks–again, as clear a case of cause-and-effect as you will ever find in economics. It is true: women–in the USA at least–reduce their birthrates when they cannot afford to have a bunch of kids (see also response to Mark below).
Mark: Again, comparing women in poor countries to women in rich countries is comparing apples to oranges. The relevant metric is to be found within the USA itself. Now, it is true that if you simply look at household incomes, household incomes of over $200K/year tend to have the lowest birthrates. But: (a) such households will tend to be older and past childbearing age; or (b) you have both partners working hard with no time for children.
The proper metric that captures what is going on is the educational attainment of the mother. That is the better proxy for a woman’s lifetime income than a snapshot of income in a given year. And in 2019 in the USA, it turns out that mothers with a graduate or professional degree have the highest birthrates (61 births per 1,000 women) whereas the birthrates for mothers who didn’t finish high school are the lowest (44% lower at 34 births per 1,000 women).
https://www.statista.com/statistics/241519/birth-rate-by-educational-attainment-of-mother-in-the-united-states/
Daniel Hess
Apr 5 2021 at 5:03pm
“comparing women in poor countries to women in rich countries is comparing apples to oranges. The relevant metric is to be found within the USA itself.”
America has been trending in a good direction.
America is admittedly better placed than many other developed countries. But we share a planet. What is true in America is not true globally.
Globally, the poorest, least educated have the most children and the richest and most educated have the least. On Earth, this is the dominant pattern. And even if America isn’t making this mistake, everyone else is. America is not an island.
If anything, the global problem is getting much, much worse, as the fertility of the most productive and innovative and educated countries drops through the floor.
If every country looked like America, things wouldn’t bode so badly for the world. Alas.
The phrase ‘may you live in interesting times’ is supposed to be a curse. Well, the most interesting times in the history of the world are ahead. :-/
Mark Bahner
Apr 6 2021 at 11:02am
Comparing any two women can be said to be comparing an “apple to an orange.” No two women are alike.
But the facts are that the world keeps getting more and more wealthy (GDP per capita continues to rise) and global fertility rates continue to fall:
Global GDP per capita is rising
Global fertility rate is falling
So there’s no evidence that there will suddenly be some sort of global increase in fertility in the future in the likely event that global GDP per capita continues to rise.
Lizard Man
Mar 31 2021 at 10:09pm
Glen Danzing has an answer to this question. (Sorry, but I think this topic should be approached with levity).
Lizard Man
Mar 31 2021 at 10:15pm
Does the logic of the arguments for NGDP level apply to population?
Separately, it would seem to me that without a growing population, savings would be difficult, unless robots and machines essentially pick up the slack in labor supply. Savings are just a claim on future goods and services right?
Scott Sumner
Mar 31 2021 at 10:31pm
You asked:
“Does the logic of the arguments for NGDP level apply to population?”
No. Monetary economics is quite different.
Mark Bahner
Apr 1 2021 at 12:00am
The problem with that hypothetical is that the evidence seems to be that humans voluntarily limit their population well before it is possible for world to become populated “until living standards fell to those of a North Korean concentration camp.”
Sub-replacement fertility
BC
Apr 1 2021 at 6:37am
We can ask questions about outcomes or questions about processes. Examples of outcomes questions are, “What is the optimal population?”, “What percentage of each race and gender should a college admit?”, and “What is the optimal income distribution?” Process questions are, “How should we determine population?”, “What criteria should admissions offices consider and how much weight should be placed on each?”, and “How should we allocate economic resources?”
Potential answers to “What is the optimal population?” include “9.3 Billion”, “more than what we have”, or “exactly what we expect to have in 50 years”. Potential answers to “How should we determine population?” include “Convene a panel of experts to determine population targets and implement a system of penalties and rewards to achieve such targets,” or “Allow couples to determine their own family size and aggregate the results.” When we know all the relevant information and how to apply it, then outcomes questions might be the questions of interest. However, if one doesn’t know or cannot know all the relevant information or how to apply it, then process questions may be more salient because they address how one goes about obtaining and applying the relevant information. Process questions about optimal population strike me as more salient than outcomes questions.
Lots of people are now advocating various child subsidies, ostensibly to achieve a desired outcome of higher population. Taxing everyone to pay child subsidies is economically equivalent to fining the childless. In turn, fining the childless is equivalent to fining people for using contraception, having abortions, and abstaining from sex, including premarital promiscuous sex that would have otherwise led to pregnancy. I suspect that many liberal advocates of child subsidies would frown upon outlawing contraception and abortion and enforcing those bans with fines and that many conservative advocates of child subsidies would frown upon mandating premarital promiscuous sex. That incoherence suggests that, when it comes to determining population, it’s actually process that matters a lot more than outcomes. Child subsidies are about just that — subsidies to those with children — rather than means to achieve a desired population outcome.
Scott Sumner
Apr 1 2021 at 3:05pm
Since I’m agnostic on the optimal population question, I’m skeptical of government programs to encourage a smaller or larger population. But I agree that these proposals often have hidden agendas.
MarkW
Apr 1 2021 at 8:57am
Isn’t it obvious that the median quality of human lives has never been higher (and the ‘misery rate’ lower) than it is now?
Isn’t it also obvious that the universe would be a better place with a 1000 inhabited worlds than possibly just this one? If you disagree, then you must think human life is a net negative and that overall utility would be maximized (at zero) with human extinction.
And can’t we aggree that gross land area per person matters less than ever? All over the world, people are gravitating away from rural and into metropolitan areas out of preference–most people do not want to be like Daniel Boone who supposedly moved farther into the wilderness when he could see the smoke out of the next chimney. Given that, it seems we are nowhere near to making the planet so crowded that the overall quality of life suffers for it.
But even for those living in relative rural isolation, hasn’t Marx’s ‘rural idiocy’ been largely vanquished by literacy, satellite TV and the internet?
Scott Sumner
Apr 1 2021 at 3:07pm
You asked:
“Isn’t it obvious that the median quality of human lives has never been higher (and the ‘misery rate’ lower) than it is now?”
Not to me. Young people today don’t seem happier than we were in the 1960s, even though in material terms they are far better off.
Mark Bahner
Apr 1 2021 at 4:57pm
Happiness, schmappiness! 😉
Just today, on NPR, they were soliciting people to call in and leave a message about how anxious each person was (what with COVID-19 and whatever).
As I commented to my parents (who were preteens and young teens in WWII), imagine if there was such a solicitation during WWII.
Homo sapiens seems to be evolving to a species without backbones. I hate that! 😉
P.S. ***Possibly, the choice of WWII was inappropriate, since such a solicitation might appear downright treasonous. But my general point stands.
MarkW
Apr 1 2021 at 8:06pm
Young people today don’t seem happier than we were in the 1960s, even though in material terms they are far better off.
Do you think the young people of today are less happy than those of 1965…in China? In Vietnam? In countries that were then behind the Iron Curtain?
And even in the U.S., I seem to remember there was a whole lot of angst, unrest, riots, and violence among young people. As a young man I’d think I’d be a whole lot happier in 2021 NOT being in jeopardy of being drafted and sent to Vietnam I’m just old enough to remember an uncle worrying about his draft lottery results whereas now I have a friend whose daughter has been living and teaching in Hanoi for a few years and really enjoying the experience.
I might agree that the 20-year-olds of 2021 seem less satisfied than those of 2000 or 2010 but I don’t think that has anything at all to do with increased population. Of course there’s no guarantee that particular cultures aren’t going to have bouts of stupidity (which we seem to be in the midst of at present), but that seems kind of irrelevant to the larger issues.
dcpi
Apr 3 2021 at 3:04pm
Scott:
I have a third grader. That group does not seem to be any more or less happy than 40 years ago. All in all they are pretty happy to be alive and they are even fun to be around. My unhappiest years were 16-25. Not sure that things are really that different.
If more people is indeed a good in and of itself and the limiting factor is Earth’s resources, Elon Musk is hitting out the park in more ways than one (space exploration and his own family).
Thomas Lee Hutcheson
Apr 1 2021 at 9:14am
Several thoughts.
Some of the downsides of falling populations stem from the way (wage taxation) we have chosen to finance pensions and health care for older people. That could change.
Some the downsides of rising population stem from the ways we fail to tax congestion externalities.
Maybe the answer lies in which policy failures one thinks is greater and easier to fix.
On balance, my gut feeling is that greater population, at least for the US would be beneficial, especially if the main route to this would be selective immigration.
Warren Platts
Apr 1 2021 at 12:02pm
This is an important topic. First a few facts: the human biomass (about 400 million tonnes) is now about 8X more than all wild vertebrates on the planet and about equal to the biomass of the world’s fishes and whales. In comparison, Antarctic krill has about the same biomass; cows are probably in the range of 600 million tonnes. Fully half of Planet Earth’s primary productivity (all the solar energy converted to chemical energy by all plants) is coopted by humans and their commensals.
Therefore, the very idea that there should be more, more, more humans strikes me as just plain crazy. It is quite clear we are already pushing the limits of what is sustainable. If you really want a lot more humans, we are going to have to expand into the galaxy, or else build humongous O’Neil cylinders. Settling Mars, even if we could terraform it to Earth-like standards, cannot hold any more people than Earth. Therefore, for the foreseeable future, while we have more humans here on Earth, we cannot have much more.
Perhaps fishery biology can help. The optimal population of a fishery is easy to specify: it’s the population level that yields the maximal sustained yield (MSY). Now, obviously, we not going to harvest humans for soylent green production. But the point is this: at MSY, that is when the population has the highest reproductive success. One could say it is the point of maximum flourishing because above the MSY point, resources become scarce, life becomes harder, population growth slows naturally.
According to the logistic equation, the point of MSY is 1/2 the carrying capacity K. An analogous example from human history is the aftermath of the Black Death in Europe. The stylized fact taught in economics textbooks is that after the population was cut in about half, good times ensued. Well, good times for workers; for the aristocrats, they were forced to accept a smaller slice of the GDP pie.
Thus, when we see birth rates decline to below replacement levels in places like Japan, Europe, and now the United States, we should accept it for its face value meaning: that the population is far above maximal flourishing. This is further evidenced by the fact that the women in the U.S. who have a graduate or professional degree have the highest fertility compared to any other educational attainment. Higher education translates into more wealth, that in turn insulates these women from the resource scarcity the others face.
Consequently, all attempts to manage either the world or the U.S. population for higher numbers are utterly misguided imho. Given the fact that we are sucking up half the world’s primary productivity and yet birth rates are declining, that tells me we are at the carrying capacity K, if not above it. Therefore, if the logistic equation is any guide, we can make a rough, first order stab at what the optimal population “should” be. And that would be about half of current levels, perhaps around 4 billion souls.
bill
Apr 3 2021 at 9:16am
I didn’t quite follow the conclusion, but I like this post. I think a gently declining global population would be a plus from here.
Warren Platts
Apr 3 2021 at 2:12pm
Now that I’ve thought about it some more, we really don’t want to be at MSY because that would require a “harvest” of humans. We should just let the population(s) find it’s natural equilibrium.
A paradox is the richer the society, the lower the human carrying capacity is (defined as the population level at which birthrates equal death rates). To continue with the fishery metaphor, it is like people in rich societies are whales, whereas people in very poor societies are little porpoises & dolphins. Obviously a given ocean territory can support more porpoises than whales. It is the same for humans: we can support a bunch of poor people, or support a much smaller population of relatively rich people.
Choose your poison! 😉
Daniel Hess
Apr 5 2021 at 4:28pm
“A paradox is the richer the society, the lower the human carrying capacity is (defined as the population level at which birthrates equal death rates).”
This is completely untrue. Europe in the year 1000 was at the Malthusian limit at 75 million people and per-capita resources were very low. Now Europe at 750 million people has a per-capita abundance that would have been unthinkable to our ancestors. The carrying capacity depends dramatically on innovation.
“To continue with the fishery metaphor, it is like people in rich societies are whales, whereas people in very poor societies are little porpoises & dolphins. Obviously a given ocean territory can support more porpoises than whales.”
This is incorrect for two reasons. First, Japanese do not need 100 times more food than Nigerians. They need a similar amount of food and if anything laborers need more food than office workers. Secondly, people do not forage in the environment. We grow food.
America grows an abundance of food for itself and then exports food to the rest of the world even though only 1.3 percent of the population works on a farm.
“From 2016 to 2018, Africa imported about 85% of its food from outside the continent”
(United Nations)
The innovative and highly economically productive people of the world (the people of the rich countries) have been feeding the world’s poor.
If the population of the world’s innovative and highly economically productive people is collapsing then it is a calamity for the world’s poor. The rich countries cannot hope to sustain the world’s poor when they are a much smaller share of the population and the relatively unproductive poor are a much larger share.
alvincente
Apr 1 2021 at 5:29pm
Warren – in my view your perspective is the same as that of Paul Erlich in his bet with Julian Simon, and is mistaken for the same reason. There is no inherent “carrying capacity,” how many people the Earth can sustain is directly dependent on how we can create and marshal resources. The billions of humans the Earth now carries could not have been sustained with the resources available a couple of centuries ago; and it is reasonable to expect that in the future far more resources will be available to us. Humans are not fish, this is the mistake Erlich made.
If you look at a map of the world showing population density, it is apparent to me that the world is underpopulated. There are only a few dense areas: The coast of China, India, western Europe, the east cost of the United States, and a few other spots. Vast areas of Asia, Africa, and the Americas are very sparsely populated and could likely support far more people. It is economics and technology that control how many people are possible, not biological calculations based on animal populations.
Warren Platts
Apr 1 2021 at 9:45pm
I see what you’re saying, and I grant your point that, yes, contra Ehrlich, we could transform Planet Earth into Trantor and have a trillion people all living on soylent green. But my argument is completely different.
In fishery and wildlife biology (and I do happen to have an M.S. degree in that field), the way you figure out the carrying capacity of a given species in a given area is not to calculate the amount of resources and then deduce how many fish or trees can be sustained. Rather, you simply look at a steady state population where the growth rate is zero (i.e., births roughly equal deaths): that’s the carrying capacity. If you harvest half that population, what is left will start growing relatively rapidly.
Thus when you look at places like Europe, Japan, and now the United States (big, necessary caveat: these are places where women have total control over the number of children they decide to produce) and you see that the population has stabilized or is declining, then, by definition, the population is at or above the carrying capacity. If the population was below the carrying capacity, then by definition, the population would be growing. Since these populations are stabilizing, I see little point for “managers” to attempt to goose these populations as if they were giant aquaculture operations.
Daniel Hess
Apr 5 2021 at 3:33pm
“Thus when you look at places like Europe, Japan, and now the United States (big, necessary caveat: these are places where women have total control over the number of children they decide to produce) and you see that the population has stabilized or is declining, then, by definition, the population is at or above the carrying capacity. ”
The problem with looking at carrying capacity as fixed is that there is no fixed carrying capacity. Carrying capacity is driven by innovation. At the time of Columbus’ arrival, the population of North America was perhaps 10 million, and at the absolute Malthusian limit. Presently, the population of North America is nearing 600 million people and most people are overweight. And we are nowhere near the carrying capacity now as far more of United States land is covered by forest than was the case in 1900.
In fact it is the populations that have the highest per capita productivity, innovation and wealth that have the lowest fertility and the ones with with the lowest productivity, innovation and wealth that have the highest fertility. If this were about carrying capacity then the countries with the most wealth per capita would have the highest fertility rates instead of the lowest.
David Seltzer
Apr 1 2021 at 7:03pm
Scott,
My SWAG. Perfect competition rests on perfect information and results in zero profit. When perfect competition is achieved, the number of people produced would be Pareto optimal. BTW. SWAG is scientific wild a-s guess.
Malcolm Kirkpatrick
Apr 2 2021 at 2:53am
Please read Garrett Hardin, _The Tragedy of the Commons”, _Science_(1967)
Earth’s human polulation cannot grow without.
Earth’s maximum possible instantaneous human population exceeds Earth’s maximum possible sustainable human population.
Earth’s maximum possible sustainable human population leaves little room for wilderness or for large terrestrial non-human animals.
Value is determined by supply and demand, therefore
A world in which human life is precious is a world in which human life is scarce.
Earth’s human population will stop growing when either (a) the human birth rate falls to meet the human death rate or (b) the human death rate rises to meet the human birth rate.
Earth’s human population will stop growing as a result of (a) deliberate human agency or (b) other.
Deliberate human agency is either (a) democratically-controlled or (b) other.
For every locality A the term “the government of A” names the largest dealer in interpersonal violence in that locality (definition, after Weber).
All human behavioral traits are heritable, therefore
Voluntary programs for population control selectively breed non-compliant individuals.
Humans who will reproduce at high density have a selective advantage over humans who require open space.
Politicians in democratic polities will not impose restrictions on human reproduction as long as other countries serve as sinks for excess growth.
Human misery is like heat; in the absence of barriers it will flow until it is evenly distributed.
Build the wall.
Malcolm Kirkpatrick
Apr 2 2021 at 1:04pm
Value is determined by supply and demand.* Therefore, a world in which human life is precious is a world in which human life is scarce.
All human behavioral traits are heritable**, therefore, voluntary programs for population control will selectively breed non-compliant individuals.
Please read Garrett Hardin, “The Tragedy of the Commons”, _Science_(1968)
*This is not an axiom of capitalist economics or of human economics; it is a fact of life. Compare the leaf surface area to root mass area of plants of the Sonoran desert to the leaf surface to root mass ratio of plants of the Amazon rain forest floor. Plot leaf surface to root mass ratio of water hyacinth as a function of dissolved nutrient.
**Turkheimer’s First Law of Behavioral Genetics.
Andrew_FL
Apr 2 2021 at 3:15pm
The optimal population of sapient beings in the universe is infinitely many.
It is not a utilitarian conclusion but an absolute moral fact that it is always better that more sapient beings exist, as many as can possibly be brought into existence, for as long as possible, from here to the cosmological horizon, from now to the heat death of the universe.
Ben P
Apr 3 2021 at 9:27pm
I think population growth will recover because I assume fecundity is slightly hereditary, so the people that prefer fewer children will produce fewer children with similar preferences and the fecund will produce more children with similar preferences. Mother Nature wants us to make more children too!
Daniel Hess
Apr 5 2021 at 3:07pm
Tyler Cowen is 100% right that “Global depopulation is the looming existential threat that no one is talking about.”
But this discussion and the comments have missed the central point of WHY that is so. It is the most economically productive countries and the most innovative people that have the most sharply decaying population exponentials. Disaster is on the way because of **who** is not having children.
If you want to know which countries negative population dynamics, and which countries are diminishing the fastest as a share of the global population, it is largely those countries that bring the most innovation and economic productivity.
The only nation with signification innovativeness (as measured by patents) and an increasing native population is Israel. In all other cases, it is the world’s most innovative and economically leading peoples that are not being replaced.
If you look at broader innovation indicators, it is even more clear that the most innovative countries and people are least fertile.
https://en.wikipedia.org/wiki/World_Intellectual_Property_Indicators
We can take the example of South Korea as a takeoff point for a proper discussion. In the year 2020, fertility was all the way down to 0.84 births per woman — and this reflects conceptions before the pandemic. In the fourth quarter, Korean fertility went all the way down to 0.75 births per woman. This is only about 1/3 of replacement, which means that cohort size shrinks by at least 2/3 with every generation (and arguably even more since they have a strong revealed preference for boys).
But South Korea is the most innovative country in the world by most innovation indicators. It is a global leader in everything from cell phones to cars, from containerships to semiconductors. The world needs far, far more South Koreans to improve life for everyone. And yet South Korea’s numbers portend not mere population decline but outright collapse within not very long.
What is true for South Korea is true of nearly every innovation power house to varying extents. Japan. Germany. China too. And now America, already a debtor nation, is developing decaying population dynamics.
At the same time, a number of very poor countries that hardly innovate at all and are locked in grinding poverty have uncontrolled population growth.
Is it possible to talk about these two opposite problems at the same time? Can we hold two thoughts in mind at once?
That the collapse of fertility in the innovating countries will break the back of the global economy in time is a certainty. There can be no other outcome.
Is the plan for the poorest and most impoverished and least innovative countries to carry everyone in the future? Will the poorest and least innovative people magically transform into South Koreans?
This of course begs the counterargument that South Korea was once poor. But the Koreans have always had extraordinary intellectual ability far above the global average. Desperately poor North Korea is nuclear power, something very many more populous and wealthy nations cannot achieve.
Tyler Cowen, Ross Douthat and Robin Hanson no doubt understand this nuance but expect people to read between the lines and understand what they mean. Speaking plainly might invite persecution.
Unfortunately the certainty of global economic collapse in time from this population dynamic will leave us no choice but to speak frankly.
Mark Bahner
Apr 7 2021 at 1:53pm
This analysis ignores the fact that Heredi Jews are the Israeli subpopulation that has the extraordinarily high fertility rate (an astounding 7 children total fertility rate, or TFR). In contrast, secular Jews in Israel have a TFR of 2.1, which is almost exactly at replacement level.
See Figure 7 for TFR by religiosity in Israel
My guess would be that the Heredi subpopulation with the very high TFR also has a very low per-capita patent-holder rate, as compared to secular Jews in Israel. So the increasing population of Israel is not driven by the patent-holding subpopulation.
Warren Platts
Apr 7 2021 at 3:16pm
I wish people wouldn’t use “existential threat” to exaggerate the danger of something that isn’t much of a threat.
The very existence of Japan or the United States or Europe is not in danger if their populations cease to grow. What we need to do is take seriously the fact that these populations, as the result of many, freely made, individual decisions have birth rates that are below replacement level. That is a signal: it is both a market signal, and a biological signal that there are enough people.
Yes, I know, you technocrats will point out that there is plenty of more food and more room for more, more, more people. However, while it is true an American doesn’t eat much more than a Nigerian, the amount of overall resources that the average American consumes are many times more. Hence my point regarding whales versus porpoises above and that paradoxically, richer societies in the 21st century will tend to have a lower “carrying capacity” compared to poorer societies. As these poorer societies get richer, their populations will cease to grow as well.
As for large populations being needed to drive innovation, I don’t see how that follows. Ancient Athens would be considered a small town by today’s standards, yet they produced many amazing thinkers. Similarly, the founding fathers who wrote the U.S. Declaration of Independence and the Constitution were another group of amazing thinkers that came from a tiny population.
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