i think we need to define limits in terms of energy. there is a certain amount of energy that comes in from the sun that life then uses to decrease entropy. that energy can be used by any form of life to do work. we broke those limits by in part by displacing a lot of other life. so yes we can probably push the limits even more and displace yet much more life on the planet. at some point however that fact will effect us unpredictably.
> i think we need to define limits in terms of energy
Ok. Let's do that. The earth receives about 10,000 exajoule per day (3850000 per year) [1]. Daily human caloric intake is 2500 calories [2]. Let's say inefficiency and the fact that you actually need food, not pure energy, let's say that means 20% efficiency, so 12500 calories per human daily. 12500 calories is about 50k joules. Things like running a tv/computer/... would be peanuts on top of that so they "come free".
So divide one by the other. The earth, without space based power, can keep about 1e18 humans alive on this planet using just earth-based solar power.
Plus you have to keep into account what humans actually do : they convert chemical energy into heat. If we cover the planet in solar panels, why couldn't we recover most of that human-generated heat ? Let's say we can recover 99% of energy that we put into humans back out, that's another factor of 100 right there.
We could use nuclear to increase that number to 1e30 or so for a millenium and if you count fusion based power, the numbers become completely ridiculous.
To put that number in perspective, take it like this : when every human alive today breeds into a population the size of today's entire human population, then we'd be near the "pure solar" carrying capacity of just the planet itself. If we were to beam power from space to the planet, we wouldn't run into the next limit until 1e50 at least.
So we are very, very, very far away, even on an exponential population curve, from the carrying capacity of the planet. When fitting an exponential curve to some sample data (very inaccurate, but good enough for a ballpark figure), I get that if the growth since WWII (1.36% per year, starting at 2000 with 6 billion people), then we'd get to 1e18 a little after the year 3400.
> we broke those limits by displacing a lot of other life
Only for a few measurements. There are a lot of problematic measurements of life that are inaccurate and therefore full of noise, and can be outright deceptive. Some of those measurements look bad : number of species, for instance. But how relevant is that number ? Sure, if it keeps dropping our zoos will become boring, but what will actually happen ? The truth is nobody knows, and there doesn't seem to be a reason, aside from nostalgia, to assume it's bad. One "real metric" that is at least measurable and I believe is meaningful : the total amount of life is total biomass, and it is pretty well known that humans have increased that by a lot.
> at some point however that fact will effect us unpredictably
It seems to me to be pretty much a given that lots of things can affect the human race unpredictably, and given how many such factors there are, it seems a safe bet that a few are indeed going to affect us (though the vast majority won't). Malthusianism and global warming are such factors, malthusianism has been proven false 3-4 times at least, and many limits to growth theories both before and after have been (I like the economic "debt limit" ones, stating that we can never have an economy larger than the value of all gold, then we passed that, then money became "loaned gold", and the next theory was that there was some factor that limits how big the economy can be n * total_gold, n was to be 10, then 100, now it's at least 100 million, and they're still at it), I wonder what the fate of global warming will be.
If you believe in Darwin and evolution, this is a positive. We will adapt to whatever effect, predictable or unpredictable, starts affecting us.
By Carnot's theorem, the maximum possible efficiency of a heat engine = 1 - (T_cold/T_hot). Using very rough figures, T_hot = body temperature = 37 C = 310 K and T_cold = average temperature of the earth = 16 C = 289 K.
Thus, the maximum possible efficiency is 1-289/310 = 6.8%.
To get 99% energy recovery, assuming human body temperature remains the same, would require that the cold side of the heat engine be at 3.1K, or only slightly warmer than the background temperature of space.
The only possible way to achieve that difference is by radiative heat transfer to space. However, we can use the temperature of the buried lunar regolith as an estimate of what the the "average" temperature of the earth could be without an insulating atmosphere. http://www.asi.org/adb/m/03/05/average-temperatures.html says it's -35 C = 238K.
Even if we could use -35C as the cold side of our heat engine, that would still only be 23% efficient, assuming maximal thermal efficiency and, you know, no air.
Nutritional "calories" are actually kilocalories (kcal), which leads to occasional confusion when trying to do calculations that relate food energetic content to other things. For example, I had a book relating someone's calculation that you should be able to diet by drinking scotch and soda because "the body must furnish 7400 calories" to raise the drink from 0°C to body temperature, which would presumably dwarf the energy input from the liquor and indeed from whatever else the drinker consumed all day. (The author agreed that this "didn't work" but didn't understand why not.)
The problem turned out to be that, while the body does indeed furnish around 7000 calories to heat up an ice-cold beverage, the drinker is consuming 2000 or more kilocalories daily, including around 100 from the drink itself.
So, you should lose a factor of 1000 for the definition of nutritional calories. But the numbers in your calculation are so staggering that this barely affects your point, which is that human population isn't close to being fundamentally physically limited by energy inputs from the Sun.
I think you're basically right conceptually, but should give more weight to the difficulty of adapting to some kinds of environmental change. There's no guarantee that human beings can invent everything we need when we need it, and some changes are difficult or impossible to reverse. So even if some limits aren't at all theoretically insurmountable, humanity could fail to surmount them because things that would need to be done can't be done in practice in the required timeframe.
Other than "nostalgia", there's also the fact that life in general is more likely to survive a changing environment if there is more variation. If there is only one species, life is much, much more likely to die out, even in the short term. I personally don't think that's important, but a lot of people do seem to have strongly held positions that the continuation of life is important for some reason.
One question that I have if there is so much energy then why is life not using more of it? I guess there are a bunch of other constraints on life other than the sun's energy so my point is off.
Conversion inefficiency, maximum conversion limits (a black leaf would burn up in full sunlight), consumption of energy by other bits and pieces of the planet other than living creatures (the atmosphere, for instance is a huge consumer, as is the planet itself, just to keep it above freezing, see also: albedo).
Evolution is constrained by its history. There could be more efficient mechanisms to use sunlight to drive metabolism, but it's simply not reachable through evolutionary means.
A couple of flaws in your back of the envelope calculations, but it doesn't change the major conclusions.
> Daily human caloric intake is 2500 calories... 12500 calories per human daily. 12500 calories is about 50k joules.
kilocalories not calories, so 50 MJ not 50 kJ.
> 20% efficiency
(...)
recover 99% of energy that we put into humans back out, that's another factor of 100 right there
Not sure how you can recover 99% of the energy while 20% was actually used efficiently, pretty much meaning with non-heat output. And you're not making new energy here, you're just reusing the 80% that was inefficient. If you want to do that, just consider the initial process was efficient.
> If we cover the planet in solar panels, why couldn't we recover most of that human-generated heat ?
Surely you mean cover the clouds with bottom-looking "solar" panels sensitive to infrared.
Anyway, this just changes things by a factor of 100000 or so, down to about 10^14 with some inevitable inefficiency before considering other energy sources, which is 100000 billion.
Finally, the current absorption by photosynthesis, that then goes into biomass is only 3000 EJ/year. If we consider 2000kcal per individual (there are about 50% women after all...), a gross estimation of what is currently extracted by the biomass would be enough for 10^12 humans, so 1000 billion.
Less than 0.0000001% of the Sun's energy output ever reaches the limits of our atmosphere, simply due to our size and distance away from the Sun.
Long-term, energy is not the key absolute problem, but actually being able to get the technology, materials, short-term energy, and political will together to be able to harness the mind-boggling amounts of space and energy that's out there.
Most developed nations currently have declining populations. For now it seems like we can simply stop population growth by bringing the rest of the world to our level of wealth. Then again there's the question whether earth has enough resources to make that even possible.
I saw someone once refer to the great potato famine as a disaster from which Ireland never recovered. From an evolutionary perspective, this is far from obvious; the famine prompted a lot of emigration to the US, with the result that the world Irish population now dwarfs the old peak Irish population, even though the population of Irish in Ireland is smaller. With large ongoing emigration flows, it's hard to say that the smaller population in Ireland reflects hard times in Ireland... it could just as easily reflect good times!
A quarter of my ancestry is from Ireland but I don't consider myself Irish. I find your post weird, how are you considering "world Irish population?"
The famine was a political issue anyways, the English oppressors could have released the abundant stores of wheat to feed the starving Irish but didn't want to depress the commodity price of wheat and were also content to let the Irish die. The Irish potato famine happened during an abundance of food withheld, which is the real tragedy.
That same story is playing out a on a much larger stage with medication and food as the elements and much of the third world in the role of the Irish. Money is a great tool, but like any tool it has good uses and bad ones.
No, the famine was an dietary issue. The Ulster-Scots communities in the north of Ireland and western Scotland also suffered potato crop failures but had a more balanced diet with much more wheat. Same in Germany and Denmark.
> Humans don’t just extract from a fixed set of resources, but can create new resources through invention.
Perhaps I am being pedantic, but that sounds like nonsense. Sure, humans invent stuff, but they don't invent the resources. They invent new ways to access previously inaccessible resources, or extract accessible resources more efficiently. But they don't magic more resources into being.
Nothing is intrinsically a 'resource'. Something becomes a resource when it can be used to further some human activity. Iron wasn't a resource until iron forging was invented. Without humans, no resources exist.
But the iron was already there before we declared it something useful. Ants use 'resources', so do bacteria so without humans resources definitely do exist and are being used actively, whether we declare something to be a resource to us or not does not change the fact that it was a resource before our wandering eye fell on it.
Asteroids are a nice example. They're 'untapped resources', objects we one day may use as resources but which for now just sit there because we haven't found a way to make tapping that resource cost efficient.
Fine: nothing is intrinsically a resource. Nutrients weren't a resource before some self replicating process started using it for some purpose, probably fairly directly related to replication.
And iron ore still wasn't a resource until humans came along and invented forging.
The term 'resource' does not describe the natural state of something. It describes a relationship between things: something is a resource for some goal(s), by some entity(ies). The relationship did not exist when the other party was not in that relationship, for instance because the other party did not exist. Thinking new resources cannot come into existence is making a category mistake, thinking whether something is a resource is absolute, intrinsic, independent of context.
We can't create matter, if that's what you're saying. But we can learn to transform or interpret previously useless things as very useful resources. For example, flint was just another valueless stone before we realized we could make fire with it, or uranium might've just been another stone before we discovered nuclear sciences. In that sense, we can indeed "create" new resources.
Well, we don't create matter. But, for example, new farming techniques do increase actual food supplies. Food is an essential resource. How much of it exists is not arbitrary and can be significantly influenced by human behavior, but we have to have additional resources, such as ideas and tools, to leverage the existing resources, such as soil and stuff that might enhance it, into something more.
I suspect that at 7 billion now, if the world population rose to even 100 billion, we'd find a way to survive. It would be a very different life experience, but it would still be life.
Able yes, but at very high risk of deadly instability through destroying most of nature and accordingly higher dependence on technology, and smoothly working social structures?
Unsustainable to me means 'unable'. If you can't sustain a model in the long term that means that sooner or later there will be a crash. Whether the number of people we can sustain long term is 10, 20 or 50 billion people is currently not known but most people that have spent significant time on this problem put the long-term sustainable number closer to 10 than to 20 billion. Now, as the article states we've consistently under-estimated these numbers but even very generous allowance for errors would cap the number that we could long term sustain in any form well below 100 billion.
I said "risk of deadly instability through destroying most of nature" but really meant to say "high risk of deadly instability through having destroyed most of nature".
I.e. we might get ever closer to a world which is sustainable in the sense that humanity doesn't live off limited resources anymore (say, using machines to convert solar power to food more directly than using plants), but where most of nature has been destroyed and hence the possibilities for recovering by falling back to (even temporarily) using reserves increasingly vanishes (no place to build cheap or simple housing anymore, no land or even suitable climate to fall back on using plants as food). Thus all sorts of small crises can each lead to a lot of dying (perhaps like today's famines in Africa, but now all over the world).
But you may know more than me and your point may well be true. (I'm not a researcher, just fantasizing. I should get some experience in mathematical modeling.)
> Grow food in cold climate (Russia, Canada and even Antarctica).
Needs an energy source
> Grow food in the ocean.
We already do this and we call it fish. We're also terribly bad at managing this very important resource.
> Grow food under ground.
Needs an energy source
> 10x+ increase in food output from the same amount of land.
Needs wildly fantastic breakthrough in practice, currently at odds with the theoretical maximum yield from acreage.
> Industrial food synthesizing.
We already do quite a bit of this but you'd have to come from an entirely different angle (such as synthesizing protein from non-biological sources, currently not a possibility).
So, with present technology and present knowledge about energy budgets and support capabilities of arable land it's as far as I can see right out.
If there is some totally out-of-the-blue breakthrough (such as atomic synthesis of arbitrary compounds combined with free energy) then sure, anything is possible. But that's the same kind of bet the cryonists (sp?) make, or even some religions, once you allow for miracles the future possibilities are limitless.
I'll be more than happy to concede that there will be improvements in yield but the amount of sunlight falling on an acre of land and the available minerals and precipitation are limiting factors, even when you factor in greenhouses, artificial lights, irrigation and so on. Hydroponics is probably eventually one of the most efficient ways of doing all this and even that has fairly hard limits in terms of energy required and amount of nutrients and water required.
> you'd have to come from an entirely different angle
Not me personally, but tens of billions of new people who would be born in the next couple of hundred thousand years.
> If there is some totally out-of-the-blue breakthrough
If in 1900-2000 food production increased 5x then it is reasonable to expect that in the next 100 years food production may increase 5x again (or more if needed).
It looks like you want to have enough food now (in 2015) in order to be able to feed world's population in 2215.
Why do you need to have that food 200 years ahead of the actual demand?
Really? Food and housing is fairly easy to solve. Canvas or wood housing and green houses and we could do it with today's technology. Even education is getting way more environmentally friendly with advances in online education resources.
The problem isn't feeding and housing people, it's flying them to Greece for a weekend vacation, buying an endless supply of electronic and motorized consumer products, and a race-to-the-bottom attitude with power generation in the developing world.
I don't think it is impossible. And humans have a way of doing things that really seem impossible at first. I'm sure a hundred years ago no one would have thought it possible to walk on the moon. We now have workable methods to turn the dirtiest of water into pure drinking water. Agriculture is a long, long way from being as efficient as it could be; we find ways all the time to quadruple the food output of a plot of land, and there will continue to be innovation in this area. Our diets are largely wasteful around the world as well, it is possible to live on much less food than the typical American eats, for example. And as for space, the world average population density per land is actually not that high; certain places are, but when spread out, there is tremendous room for physically placing more people. So I'd say it is well within possibility to make 100 billion people stay alive. But, a lot would change to do so.
Why is this issue getting so much attention? It is a problem that will solve itself, wherever the limit is. The only reason to worry about where the limit is, is if you want to avoid it with birth control so that some nicer forces than famines or resource wars keep the population stable. But even that seems unnecessary, at least in the developed world, because the population growth rates or even the populations are already declining. Which of course is a good thing, why would you prefer a more densely populated world over the status quo? Why would you want to raise child after child if two and a half are enough to sustain the population?
It will solve itself, but billions of people might die as part of the solution. Mankind will survive, but for the individual some worrying might make sense.
The people that can prevent overpopulation don't suffer from it, the people that suffer from it can't prevent it. So it's more of worrying for once children's children.
But migration and the normal population growth are qualitatively different - normal population growth is an exponential phenomenon given a constant growth rate, migration is a linear phenomenon given a constant migration rate. And at least in developed countries I see now real issues controlling both forms of growth, limiting the number of immigrants as well as establishing a two children policy if required.
> Why would you want to raise child after child if two and a half are enough to sustain the population?
Simple: because you believe your (religion, parenting skills, values, heritable traits) are the best. Having a dozen kids per family is a leading way to innundate society with whatever you think is awesome.
There are also cultures that vanished after thousands of years, and crisises in which millions of people died. Human ingenuity and technological progress didn't solve every problem. We just forgot about the dead (classic survivor bias). Collapse by Jared Diamond has some examples of societies that failed - by comparison, our current civilization is very young and hasn't really "played out" yet.
Maybe the estimates of Malthus were wrong, but the underlying concern is still correct. Our current food production is not sustainable because it relies on non-renewable energy sources. I don't claim no solution can be found for that, but there is also no reason to believe there will be a solution.
Another way to look at it makes it very plain: the surface area of earth certainly is limited. So if population would grow forever, we would reach a point where every person would only have one square foot of ground to live on.
Even that might be doable - we could live in a stacked way (skyscrapers), or Matrix-Style in coffins with virtual environment. Nevertheless it doesn't seem like a very desirable future.
Population limits are certainly a well-documented phenomenon. Chinese history shows excellent conformance to a "punctuated equilibrium" model -- the population is stable nearly all the time, with two obvious sudden increases. (From memory, I believe the increases correspond to (1) the local development of a new, more productive strain of rice, and (2) the introduction of crops from the new world.)
The inference is painfully obvious: for most of history, China has been populated at its own carrying capacity. The fact that the limit was broken (really, raised) a few times doesn't mean the limit isn't a worthy concept.
My question is why do we need more people or want to encourage or allow it to occur?
My immodest proposal is to introduce a natural decline in human populations to more easily sustainable levels via the introduction of a reproductive "right": every individual when born is entitled to one child.
A couple, then, could have a family with two children. Those who aren't interested in having children could sell their "right" off on a market to people who want to have more than their one child individually, so a couple could buy the rights to more children and a larger family from those who don't want to have children. The market could even fractionalize/derivatize those rights so that individuals could sell "half" a childbirth right and two of those individuals could have a family with one child.
The best part is, at two children per two parents, it's lower than the replacement rate of "2.1" which means population levels would humanely decrease with no need for wars or murder.
Our current societies are predicated on larger youth populations than parent populations to support us in our old ages, but this strategy combined with robotic technology for the elderly and post-scarcity economics would free us from that pyramid scheme. This helps support a basic-income type scenario for those people who assume that everyone (or 'THOSE PEOPLE') living in our society will just have tons of kids due to boredom. Like the fears trotted out about "welfare queens" having tons of kids because they supposedly get "free stuff."
Why is lower or stable population of such an imperative that such a totalitarian invasion of natural rights needs be imposed? There are plenty of advantages to larger populations - more people to take part in the creative processes of production, for one.
The disadvantage is the dubious assumption of inevitable resource scarcity. If resource scarcity has yet to become a major problem, and may not in the foreseeable future, why impose population limits?
Citing "WORLD POPULATION PROSPECTS: THE 2015 REVISION" page 10:
"Globally, total fertility is expected to fall from 2.5 children per woman in 2010-2015 to 2.25 in
2045-2050 and to 2.0 in 2095-2100 according to the medium-variant projection. However, in
Europe and Northern America, total fertility is projected to increase between 2010-2015 and
2045-5050 from 1.6 to 1.8 children per woman in Europe and from 1.86 to 1.9 children per
woman in Northern America. In Africa, Asia, Latin America and the Caribbean, and Oceania,
fertility is expected to fall between 2010-2015 and 2045-2050, with the largest reductions
projected to occur in Africa. Thus, in all major areas of the world, fertility levels are projected to
converge to a level at or just below the replacement level by 2095-2100"
According to Swedish professor Hans Rosling the fast population growth is coming to an end and the population size is expected to stabilize at 11 billion people by the end of this century. His statistics and predictions are based on data from the UN Population Division.
Yikes. I didn't realize the population density in Mumbai was near 53k people per sq. mile. Apparently Manila is nearly twice that at 111k.[1]
Still, it surprises me overpopulation fears are so commonly expressed. Seems like a greatly overblown meme that will end up doing more harm than good. Much like Malthus opposing projects to feed the poor and hungry, I sometimes hear people going as far as saying we (meaning relatively wealthy, white Americans) should just "let them die" when it comes to impoverished people all over the world. Despite the fact that, if energy consumption and environmental damage is the fear, people in industrialized countries use as many resources as dozens, hundreds, maybe thousands of lives in the "developing" world.
The world could likely support orders of magnitude more people than we give it credit for. We haven't even started harnessing materials from space industry, space-based solar power, or using the oceans and seabed as living space. There's another 70% of the Earth's surface that hasn't even been touched yet, and that percentage grows even more when you consider the vertical spaces available within it. The overpopulation meme seems more dangerous to global welfare than actual overpopulation has ever been thus far.
The world probably could support lots more people than it has now. The question is, why? If we believe 30 billion people is possible, should it be a goal? What's better about 30 billion than 6?
1) Reproduction is a natural right, and some people would consider having children to be a great fulfillment. The evolutionary basis of this desire would make it all the more powerful, and restricting it would only cause the drive to grow stronger over time (as traits evolved to promote the circumvention of the restrictions).
2) If there's no specific advantage to a lower or stable population, why is any particular number preferable to another?
3) There are lots of advantages of large population: larger communities for people with low-frequency deviations from social norms, a broader spectrum of human social and psychological possibilities represented, increased production and creative capacity, greater base of working-age citizens to support the non-working portion (retired, children), more people at the top of the bell curve to draw from for important positions (better leaders, more geniuses, etc)... This is not an exhaustive list.
4) Likely other advantages as well, which would seem to counter the disadvantages of larger population, judging from past human history (and assuming no weird non-linear relationships). If the world is better with fewer people, would you want to go back and live in a world with only 100,000? 1,000,000? Some other specific number?
1. Reproduction is not a natural right. If you reproduce beyond a sustainable level your offsprings will pay for that with reduced life expectation and being unable to reproduce in consequence. It's essentially the same thing that happens in predator prey cycles. And you don't have to cease reproducing altogether, just limit it to a sustainable level of about one child per human.
2. There are of course advantages to stable population sizes, most importantly resources will last longer and allow sustaining human society for longer.
3.1. larger communities for people with low-frequency deviations from social norms
It is not obvious to me why that is a good thing.
3.2. a broader spectrum of human social and psychological possibilities represented, increased production and creative capacity
That seems to be the best argument for larger populations besides increased production capacity because that is countered by an increased consumption.
3.3. greater base of working-age citizens to support the non-working portion (retired, children)
That is not true for a larger population, the proportion is the same as for a smaller one. It is only true while the population is growing and that is either unsustainable or the effect is unimportant if the growth is marginal.
3.4. more people at the top of the bell curve to draw from for important positions (better leaders, more geniuses, etc)
That is essentially the same argument as 3.2.
4. Smaller populations are not necessarily better, you benefit from decision of labor, scale effects, you are more resistant to disasters. The optimum is definitely somewhere in the middle, it is neither one human that can no longer reproduce and will easily go extinct, and it is also not ten to the hundred for obvious reasons. The question is therefore definitely not whether or not we should seek for a stable population, it is where the most desirable level is.
And here I argue we should first bring the entire world population to the levels of wealth, education and consumption of the middle class of leading developed countries and then we can have a look at how much resources are left, what happened to environment and climate, whether we need more smart people.
Fortunately for those of us who don't want to see humanity ruled as you suggest, it seems pretty well established that reproduction is a fundamental human right.
Of course there are no fundamental rights. If I had the largest gun in the world I could just kill everyone denying them all rights or force them to do whatever pleases me. Rights are agreements between humans - you want to live, I want to live, so let's agree that killing people is a bad thing, let's have a right to live. Nothing more, nothing less.
So if the population grows to some level that becomes a danger for the sustainability of our society, then it is in everyone's self-interest or the interests of their children to voluntarily limit the number of children they have. And if the majority of the people agrees on that, then having more children than the society believes you should have becomes a punishable misbehavior.
So right now you can imagine to have the right to reproduce but that is only because we did not yet have the need to regulate it because the population is not yet too large. But there is absolutely nothing that makes this an eternal truth. Once the population reaches a critical level you face the decisions to either limit reproduction or to see your children live a miserable life in an overcrowded world. I would definitely vote for limiting reproduction because I value my few children having a good life way more than having many children having a miserable life.
And this has nothing to do with being ruled in one way or another, the society itself should come to the conclusion that it is a necessary policy.
Agreed, that was not really a convincing argument unless you already believe that there are some absolute rights. Let's attack this from a different angle.
Where are those rights coming from? And do they only apply to humans? Why? Why not to primates? If they apply also to primates, are lions hunting and killing primates - not sure if they actually do - violating basic primate rights? How do you come to know about your fundamental rights? Could you still come up with the same ideas if you were the only human on earth?
And more specifically, if reproduction is a fundamental right, can you rape other humans in case no one voluntarily wants to reproduce with you? You probably don't think that, so you are not really arguing for an ultimate right to reproduce but the right to do so with consent. This again raises the question of incest. Why can we outlaw incest when you have a fundamental right to reproduce. Because bad things are likely to happen to possible offspring? But so does reproduction leading to overpopulation just not in such a direct way.
Absolute rights and a right to reproduce in particular are - at least in my opinion - hard to defend positions. The only more or less reasonable argument I can think of is declaring that those absolute rights are a god given thing and period. In that case there is not much I could argue against besides the believe in a god in the first place.
> Reproductive rights began to develop as a subset of human rights at the United Nation's 1968 International Conference on Human Rights.[4] The resulting non binding Proclamation of Teheran was the first international document to recognize one of these rights when it stated that: "Parents have a basic human right to determine freely and responsibly the number and the spacing of their children."
To answer your question of where those rights come, they come from a international agreement that these principles should be the guide to a human and humane culture. More about this is available from https://en.wikipedia.org/wiki/Natural_and_legal_rights . I think it's best to consider this a moral philosophy that exists only as part of a consensual reality.
Regarding animal rights, there is less agreement on a framework for how to handle those. Animals cannot enter into a social charter, and it is difficult for them to voice objection about mistreatment. Most about this is available from https://en.wikipedia.org/wiki/Animal_rights .
> "Why can we outlaw incest when you have a fundamental right to reproduce."
These rights are not absolutes but exist in tension. While we have agreed that there is a fundamental right to free speech, time, place and manner restrictions are allowed. While we have agreed that there is freedom of movement, such freedom may be limited in times of quarantine.
Thus, simply pointing out that there is a restriction on the right of reproduction does not make it less of a right than the rights of movement and of free speech.
> if reproduction is a fundamental right, can you rape other humans
ryanwaggoner was likely being brief on the expectation that you could do some research yourself and determine that 'Reproduction is a natural right' is a short-hand for a more lengthy and nuanced definition. Quoting now from the Cairo Programme of Action at https://en.wikipedia.org/wiki/Reproductive_rights#Cairo_Prog... :
> Reproductive health is a state of complete physical, mental and social well-being and not merely the absence of disease or infirmity, in all matters relating to the reproductive system and its functions and processes. Reproductive health therefore implies that people are able to have a satisfying and safe sex life and that they have the capability to reproduce and the freedom to decide if, when and how often to do so.
You can see that the 'freedom to decide if, when and how often to do so' includes all participants. Thus, rape is not part of the right to reproduce, as it is generally understood.
Rape is also in tension with other rights, such as the right to free association.
> "... absolute rights are a god given thing and period"
Humans created all the gods. Therefore humans can create human rights.
> "Could you still come up with the same ideas if you were the only human on earth?"
Human rights guide how humans should be treated. If I were the only human on earth, there would be no need for the moral philosophy of human rights, just like there would be no need for thespian, oratory, or square dancing knowledge. I doubt I would be clever enough to come up with those ideas on my own.
This is getting out of hand. The original point was that reproduction is a natural right. In the given context I interpreted that to mean that there is a right to reproduction we can not interfere with in the same way as we have to take the laws of physics as given. I opposed that by stating that rights including human rights are a manmade thing.
I am not sure whether you intended it this way but in my view your comment supports that position because you are mentioning pretty recent conventions, tensions between rights and so on. I see nothing in your comment that is incompatible with imposing restrictions on reproduction if this is deemed necessary to sustain a healthy human society.
And I didn't want to discuss animal rights and the other things I mentioned, I only wanted to provoke some thoughts about related things in the hope to inspire the insight that rights are very different from physical laws insofar that we humans make them up to achieve behaviors and outcomes we deem desirable, that they are not given eternal truths.
"In the given context I interpreted that to mean that there is a right to reproduction we can not interfere with"
Exactly. And no one with experience on the topic means that when they talk about natural rights, so you are misinterpreting qrendel's statement "Reproduction is a natural right."
But he obviously must understand it in this way, maybe not as unmovable as the laws of physics but at least in the way that we can not or should not interfere with the right to reproduce in order to prevent overpopulation. Otherwise it makes no sense to point to the right as an argument against controlling reproduction.
qrendel is clearly wrong about genetics as the timescale isn't long enough evolutionary changes to take place. Only 2-3 generations back, it wasn't uncommon in the US to have 8+ children, so clearly cultural effects are much stronger than inheritable genetic factors. See also the one child policy in China as a example of how the timescale is too short for evolutionary feedback.
qrendel is clearly wrong about population dynamics, as 'greater base of working-age citizens to support the non-working portion (retired, children)' only applies for an exponentially growing population, which must stop at some point, for clearly physical reasons like the Sun not providing enough energy.
qrendel also prefers city life, as seen in the assumption that the presence of more people means that those with uncommon interests "will be able to form communities of people with similar interests". This view excludes those who want to go for long walks alone on the beach, or hate living where they can see the lights of their neighbors, or want the local ecosystem to continue to support wildlife that does poorly around dense human habitation.
As qrendel does not believe there is resource scarcity, than that's only because qrendel does not regard things like '5 million wild buffalo freely roaming the US plains' or 'ability to see the Milky Way in the night sky' as resources. These are certainly not critical to what's needed for the human body to survive, but survival is only the bottom of Maslow's hierarchy of needs.
Despite those wrong statements, and incorrect generalization, I cannot tell from what qrendel wrote if "natural right" is used as something other than how it's generally used. However, it is possible to have both reproductive rights and a stable population, as we see in many of the countries which are below the replacement level of fertility, so these are not in direct opposition.
When you said 'Reproduction is not a natural right', I think you meant to say 'population growth to resource limits is not a natural right'. I and (it appears) ryanwaggoner were thrown off by your use of qrendel's phrase with your interpretation of what qrendel meant.
> the timescale isn't long enough evolutionary changes to take place.
Stabilizing population at a limited number would presumably be done indefinitely, not for a brief period and then removed. Therefore natural selection would have time to take effect. It obviously has not since the institution of the one child policy or the development of birth control, which were recent developments on an evolutionary timescale.
> only applies for an exponentially growing population, which must stop at some point, for clearly physical reasons like the Sun not providing enough energy.
This discussion keeps going back and forth between needing to implement population controls now, or sometime in the foreseeable future, versus the fact that the entire Hubble volume of the universe likely has some total carrying capacity. Saying that even something like a Dyson sphere surrounding the sun would only provide finite energy is not a valid reason for population controls here and now.
> prefers city life
Not really, but preferences aside, most living apart from civilization still benefit from a larger civilization to support their needs. Some may prefer to "live off the land" with no technology, but even those living the quiet life can still enjoy things like advanced medical care or a broader range of products and services delivered to them, if they so choose. Population doesn't remove any possibility of quiet walks in nature or ability to see a starry sky at night, though would perhaps make them a scarcer resources. They are, for example, still available to people now, despite a world population of over seven billion. The fact that in some distant future unbounded population growth would lead people to outnumber the number of atoms in the universe isn't a remotely relevant consideration towards whether implement population controls soon.
> Therefore natural selection would have time to take effect
Again, evolution does not work that way. Evolution doesn't care if a species goes extinct because it doesn't breed enough.
Plus, consider a 1% growth rate per year. In 1,000 years the population will increase over 20,000-fold. With 0.05% growth it takes a bit under 2,000 years for the same growth. But 2,000 years is nowhere near enough for evolution to influence humans.
> not a valid reason for population controls here and now
I never said it was. Not only that, I say that they were not incompatible, and used as my examples the many counties with full reproductive rights and a birth rate which is below what's needed for replacement and which don't have population controls.
> though would perhaps make them a scarcer resources
Yes, that's exactly my point. I'm glad you agree that these are scare resources.
> They are, for example, still available to people now, despite a world population of over seven billion.
No. Some of these scare resources are gone.
I gave one example, our buffalo resources which once numbered it the millions. You probably rejected it out of hand, but that's because you grew up in a culture which doesn't have it. But the US destroyed that resource in part to destroy the way of life for the Plains Indians, and open up the Plains for the expansion of the predominately white population with a very different culture.
You are repeating the same paternalism when you write "most living apart from civilization still benefit from a larger civilization to support their needs."
Who are you to say that everyone must live with that tradeoff? What ways of life will you want destroyed to support the 1000x large population you urge on us?
Evolution - You seem to be assuming no mutation will come into existence which will promote increased desire to reproduce. Since there are behavioral and psychological traits influenced by genetics that promote greater desire for children, this seems far fetched. (I don't have a citation, but this seems almost certain.)
Rate of evolutionary change depends on the selection pressures on the allele in question. There are formulas for calculating both the probability a mutant allele goes to fixation[1] as well as the expected number of generations for it to do so[2]. With high selective pressures evolution on the scale of a few thousand years is certainly possible - the time taken for lactase persistence to develop in humans is estimated at around 3,000 years.[3] In the extreme case, if all individuals lacking a given dominant allele are removed from the population, it would only take a single generation. So, no. Though I admit the number of generations does increase with the natural log of the population size, so it would take longer with greater population sizes.
Buffalo - Current population estimates are around 500,000 in the US. Given that large herds of protected buffalo and many locations with low light pollution still exist, you've failed to provide any examples of experiences that are forever gone.
Of course some situation can always be constructed. You can't find 20-30 million buffalo anymore, just as extinct animals are gone (ignoring current work by George Church and others on de-extinction), just as no two people can simultaneously be the US President or first man on the moon. Some particular version of experiences are constantly being made unavailable, and that's a fact of life regardless of population.
As for the Plains Indians, I don't think that genocide was caused by overpopulation so much as the US government's desire for westward expansion. Sure, it might not have happened if the population had stayed much smaller, but those aren't the only two possible outcomes. It's not as if resource availability had been exhausted in the east.
Aside from that, if you go back and read, you'll see my claim was that there are advantages to larger population, not that it was necessarily a moral imperative. (The only argument for it as a moral imperative I can think of would rely on the assumption that future unborn lives should have moral relevance to us now.) Even if I were arguing that claim, it would be equally paternalistic for one to dictate what state the world should be in simply to protect experiences they prefer.
> I don't have a citation, but this seems almost certain
Like I said, you do not understand evolution.
Yes, I know about the short timescale for lactase persistence. You'll note that it's two mutations.
Now you need to demonstrate that "increased desire to reproduce" is something that 1) is directly traceable to genetics, 2) is only a few mutations away, and 3) the intermediate forms lead to better evolutionary advantage. All you have is an unfounded belief.
From a paleobiology perspective, human population was stable for a much longer time than this relatively recent exponential expansion phase. If there were such thing as a genetic imperative pushing humans towards higher fecundity, it would have occurred long ago.
> Buffalo
This is why I said millions, not 500,000. You'll notice that there are no Plains Indians living as they once did.
> Some particular version of experiences are constantly being made unavailable
Yes. And who are you to say that your belief in exponential population growth gets priority over the experiences that others want to have?
> I don't think that genocide was caused by overpopulation so much as the US government's desire for westward expansion
Interesting how you managed to decouple population pressure and western expansion. (Note that I don't say "overpopulation" but "population pressure".) Do you think the following summaries are wrong?
"With the Louisiana Purchase and subsequent land acquisitions, U.S. territory grew exponentially in the first half of the 19th century. Populations huddled on the east coast saw grand opportunities to move into more expansive areas where land was cheap and more arable than it was back east, particularly in New England." - http://www.ask.com/history/were-reasons-westward-expansion-9...
"In order to grow, the capitalistic economy and republican form of government needed surplus land and abundant natural resources such as wood, fossil fuels, minerals, and water. Many feared that without a surplus the parceling of limited resources to a growing population would eventually lead to class conflict. Not everyone embraced this philosophy." - http://www.encyclopedia.com/doc/1G2-3406401030.html
"The most important forces [in the westward expansion] are population growth and the decrease in transportation costs," Vandenbroucke said. "Population growth is mostly responsible for the investment in productive land - without it less than half of the land accumulated in 1900 would have been accumulated." - http://www.eurekalert.org/pub_releases/2008-02/uosc-wcw02280...
> The United States, while intending never to acquire lands from the Indians otherwise than peaceably, and with their free consent, are fully determined, in that manner, progressively, and in proportion as their growing population may require, to reclaim from the state of nature, and to bring into cultivation every portion of the territory contained within their acknowl...
A pointless and inflammatory statement that you had, in fact, not made up until this point. This is getting ridiculous, and sidetracking from the original discussion on the viability or necessity of population controls.
This discussion seems to have been reduced to your assumption that there exists no series of favorable mutations which lead to increased desire to reproduce or to circumvent population controls. You know as well as I do that it is infeasible for me to give you an exact list of mutations which will affect biochemical pathways in such a way to as dictate the outcome of reproductive behavior, just as it is infeasible for you to show that no such series of mutations exists. This would include, among other things, no mutations affecting psychological attitudes regarding children, effectiveness of various birth control methods, or the balance of desire for sexual intercourse against other biological imperatives, and despite changes in external environment and other selection pressures.
Your argument could as well be used to argue against evolution entirely, since there are plenty of biological traits across species for which the exact series of favorable mutations that lead to them is not known. This is basically a claim that you will not believe evolution towards a specific outcome is possible unless you are shown the exact series of favorable mutations that maintain stable biochemical pathways in the organism the entire way. If you really believe that genetic changes affecting reproductive behavior are that unlikely, or that humans have already maximized such things despite major and recent environmental changes to selection pressures such as the introduction of birth control are so unlikely as to be effectively impossible, that's your own belief which I doubt you have any extensive evidence to support.
I really doubt that I am the one with a poor understanding of evolution here, but since this has been reduced to a basic difference of opinion about the likelihood of an occurrence (development of mutations favoring the particular outcome) that neither of us seems able to quantify, I see little reason to continue. This seems to be the fundamental disagreement here.
> Do you think the following summaries are wrong?
My claim was that those were not the only two possible outcomes, meaning genocide of the Native Americans versus a Malthusian population collapse amongst the settlers. The expansion west at the expense of native peoples was also due to the fact they devalued the lives of Native Americans relative to their own desire for expansion. Why inhabit smaller territory when you can claim more at the expense of the lives of others you do not value? Had the value of human life been greater to them than the value of the land they stole, the expansion would not have proceeded as it did.
What is the relevance of the genocide of the Native Americans to the original discussion? This was about reasons for continuing population growth versus stabilizing it, which led to whether reproduction is a natural right, and what the advantages of larger population are.
If you think population growth has led to genocide throughout history, and will continue to do so in the future, you must be arguing against the agricultural revolution entirely (some do think the agriculture was a net negative, e.g. Jared Diamond). Population controls should have been imposed in the ancient past and the world's population is already too large. That would negate most of the advances made by civilization since then, as well as all the cultural processes and technologies that can only be sustained by a larger civilization. It would also certainly be an attempt to impose your judgment about superior ways of life onto the rest of the world.
I'm fairly skeptical that's actually your claim, though. If this is going to continue, I'd really rather refocus on the original discussion, regarding the pros vs. cons of larger populations or the ne...
While westward expansion cause pressure on vestigial Aboriginal populations, note that this was incidental compared to the genocide cause simply by the first European ships making land. It's recently been estimated that between Christopher Columbus' first landfall and the first European colony, around 100 North Americans died of diseases they were spectacularly unequipped to resist. Perhaps the biggest die-off in all of human history.
3.1 - A good thing because people with unusual interests and personality traits will be able to form communities of people with similar interests. For example, in a town of a thousand people, you might be the only one who enjoys an odd hobby like underwater hockey (it's a real thing). In a city of ten million, there may be hundreds or thousands of people to form an entire league with. "Deviations" as used wasn't intended to have a pejorative connotation.
3.2. Contradicts the basic premise (no immediate resource limit) and the original article. The world has become richer despite growing population, because production has outrun consumption. No reason to think it will stop in the immediate future, any more than it did in Malthus' time.
3.3. You're simultaneously saying the economic problems arise when population stops growing and becomes stable, and supporting ending population growth in favor of a stable population. If there's a limit where quality of life decreases due to increasing population, we haven't hit it yet, given that quality of life and per capita wealth is still improving globally, so there's no reason to put the brakes on before we even know where it is.
> it is also not ten to the hundred for obvious reasons.
We're assuming technology and productive capacity also improves to keep up. We're also nowhere near 10^100. Nor do we know where this hypothetical optimum is. Population controls should be a last resort to solving problems we are't facing yet, not done just because a theoretical optimum for quality of life may exist at some hypothetical large number.
3.1. But that also means that all the bad minorities can form stronger groups and be potentially more impactful. If you can not play underwater hockey you might pick some other form of hockey instead. Maybe it makes you a bit less happy but what is the effect of a less fragmented society? I am not dismissing the idea that there might be a positive effect but I am not obviously convinced.
3.2. I would argue that the increase in wealth is mostly due to increased productivity and not due to population growth and therefore could continue even without further population growth. Population growth is certainly not totally irrelevant due to scale effects but I don't see that simply doubling the population would lead to significantly increased wealth.
3.3. That is not what I am saying. Having a pyramid shaped age structure is an easy way to have a lot of workforce available to support the elderly but that structure is not the result of a large population but of an growing population. And in order to be a significant effect you can not have just a tiny bit of growth but a substantial amount of growth is definitely unsustainable.
The limit definitely exists but I also think we will not hit it, we will not need any (large scale) birth control policies because the birth rate will drop enough with increasing wealth. Looking at developed nations it looks actually more like we will have to incentivize having more children in order not to go extinct.
I'm not so surprised about overpopulation fears.
We have a non-sustainable use of non-renewable resources. The problem is that especially in the wealthy countries this is hardly visible. We add 1 hectare of forest and at the same time somewhere else in the world 10 hectares are destroyed.
Basically the argument that Malthus was wrong and thus we shouldn't worry about overpopulation is the same as ignoring upcoming problems and saying that we will solve them when they will come up.
We as humans can solve problems but sometimes we're destroying much in the process, we're not fast enough or it's even just not possible. There have been numerous catastrophes and downfalls in human history and the amount of nature we destructed is extreme.
Maybe we can have orders of magnitude (10 billion, 100 billion) people living on this planet, but the question is whether it would still be livable, especially without nature.
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[ 3.5 ms ] story [ 140 ms ] threadOk. Let's do that. The earth receives about 10,000 exajoule per day (3850000 per year) [1]. Daily human caloric intake is 2500 calories [2]. Let's say inefficiency and the fact that you actually need food, not pure energy, let's say that means 20% efficiency, so 12500 calories per human daily. 12500 calories is about 50k joules. Things like running a tv/computer/... would be peanuts on top of that so they "come free".
So divide one by the other. The earth, without space based power, can keep about 1e18 humans alive on this planet using just earth-based solar power.
Plus you have to keep into account what humans actually do : they convert chemical energy into heat. If we cover the planet in solar panels, why couldn't we recover most of that human-generated heat ? Let's say we can recover 99% of energy that we put into humans back out, that's another factor of 100 right there.
We could use nuclear to increase that number to 1e30 or so for a millenium and if you count fusion based power, the numbers become completely ridiculous.
To put that number in perspective, take it like this : when every human alive today breeds into a population the size of today's entire human population, then we'd be near the "pure solar" carrying capacity of just the planet itself. If we were to beam power from space to the planet, we wouldn't run into the next limit until 1e50 at least.
So we are very, very, very far away, even on an exponential population curve, from the carrying capacity of the planet. When fitting an exponential curve to some sample data (very inaccurate, but good enough for a ballpark figure), I get that if the growth since WWII (1.36% per year, starting at 2000 with 6 billion people), then we'd get to 1e18 a little after the year 3400.
> we broke those limits by displacing a lot of other life
Only for a few measurements. There are a lot of problematic measurements of life that are inaccurate and therefore full of noise, and can be outright deceptive. Some of those measurements look bad : number of species, for instance. But how relevant is that number ? Sure, if it keeps dropping our zoos will become boring, but what will actually happen ? The truth is nobody knows, and there doesn't seem to be a reason, aside from nostalgia, to assume it's bad. One "real metric" that is at least measurable and I believe is meaningful : the total amount of life is total biomass, and it is pretty well known that humans have increased that by a lot.
> at some point however that fact will effect us unpredictably
It seems to me to be pretty much a given that lots of things can affect the human race unpredictably, and given how many such factors there are, it seems a safe bet that a few are indeed going to affect us (though the vast majority won't). Malthusianism and global warming are such factors, malthusianism has been proven false 3-4 times at least, and many limits to growth theories both before and after have been (I like the economic "debt limit" ones, stating that we can never have an economy larger than the value of all gold, then we passed that, then money became "loaned gold", and the next theory was that there was some factor that limits how big the economy can be n * total_gold, n was to be 10, then 100, now it's at least 100 million, and they're still at it), I wonder what the fate of global warming will be.
If you believe in Darwin and evolution, this is a positive. We will adapt to whatever effect, predictable or unpredictable, starts affecting us.
[1] https://en.wikipedia.org/wiki/Solar_energy [2] http://www.webmd.com/diet/estimated-calorie-requirement
Thermodynamics doesn't work that way.
By Carnot's theorem, the maximum possible efficiency of a heat engine = 1 - (T_cold/T_hot). Using very rough figures, T_hot = body temperature = 37 C = 310 K and T_cold = average temperature of the earth = 16 C = 289 K.
Thus, the maximum possible efficiency is 1-289/310 = 6.8%.
To get 99% energy recovery, assuming human body temperature remains the same, would require that the cold side of the heat engine be at 3.1K, or only slightly warmer than the background temperature of space.
The only possible way to achieve that difference is by radiative heat transfer to space. However, we can use the temperature of the buried lunar regolith as an estimate of what the the "average" temperature of the earth could be without an insulating atmosphere. http://www.asi.org/adb/m/03/05/average-temperatures.html says it's -35 C = 238K.
Even if we could use -35C as the cold side of our heat engine, that would still only be 23% efficient, assuming maximal thermal efficiency and, you know, no air.
The problem turned out to be that, while the body does indeed furnish around 7000 calories to heat up an ice-cold beverage, the drinker is consuming 2000 or more kilocalories daily, including around 100 from the drink itself.
So, you should lose a factor of 1000 for the definition of nutritional calories. But the numbers in your calculation are so staggering that this barely affects your point, which is that human population isn't close to being fundamentally physically limited by energy inputs from the Sun.
I think you're basically right conceptually, but should give more weight to the difficulty of adapting to some kinds of environmental change. There's no guarantee that human beings can invent everything we need when we need it, and some changes are difficult or impossible to reverse. So even if some limits aren't at all theoretically insurmountable, humanity could fail to surmount them because things that would need to be done can't be done in practice in the required timeframe.
> Daily human caloric intake is 2500 calories... 12500 calories per human daily. 12500 calories is about 50k joules.
kilocalories not calories, so 50 MJ not 50 kJ.
> 20% efficiency (...) recover 99% of energy that we put into humans back out, that's another factor of 100 right there
Not sure how you can recover 99% of the energy while 20% was actually used efficiently, pretty much meaning with non-heat output. And you're not making new energy here, you're just reusing the 80% that was inefficient. If you want to do that, just consider the initial process was efficient.
> If we cover the planet in solar panels, why couldn't we recover most of that human-generated heat ?
Surely you mean cover the clouds with bottom-looking "solar" panels sensitive to infrared.
Anyway, this just changes things by a factor of 100000 or so, down to about 10^14 with some inevitable inefficiency before considering other energy sources, which is 100000 billion.
Finally, the current absorption by photosynthesis, that then goes into biomass is only 3000 EJ/year. If we consider 2000kcal per individual (there are about 50% women after all...), a gross estimation of what is currently extracted by the biomass would be enough for 10^12 humans, so 1000 billion.
It's worth distinguishing between the theoretical maximum carrying capacity of the planet, and the current carrying capacity, which is lower.
It's worth distinguishing between the theoretical maximum carrying capacity of the planet, and the current carrying capacity, which is lower.
Long-term, energy is not the key absolute problem, but actually being able to get the technology, materials, short-term energy, and political will together to be able to harness the mind-boggling amounts of space and energy that's out there.
In terms of energy: definitely. Nuclear or now solar suffices.
The famine was a political issue anyways, the English oppressors could have released the abundant stores of wheat to feed the starving Irish but didn't want to depress the commodity price of wheat and were also content to let the Irish die. The Irish potato famine happened during an abundance of food withheld, which is the real tragedy.
No, the famine was an dietary issue. The Ulster-Scots communities in the north of Ireland and western Scotland also suffered potato crop failures but had a more balanced diet with much more wheat. Same in Germany and Denmark.
Perhaps I am being pedantic, but that sounds like nonsense. Sure, humans invent stuff, but they don't invent the resources. They invent new ways to access previously inaccessible resources, or extract accessible resources more efficiently. But they don't magic more resources into being.
Asteroids are a nice example. They're 'untapped resources', objects we one day may use as resources but which for now just sit there because we haven't found a way to make tapping that resource cost efficient.
And iron ore still wasn't a resource until humans came along and invented forging.
The term 'resource' does not describe the natural state of something. It describes a relationship between things: something is a resource for some goal(s), by some entity(ies). The relationship did not exist when the other party was not in that relationship, for instance because the other party did not exist. Thinking new resources cannot come into existence is making a category mistake, thinking whether something is a resource is absolute, intrinsic, independent of context.
We can't create matter, if that's what you're saying. But we can learn to transform or interpret previously useless things as very useful resources. For example, flint was just another valueless stone before we realized we could make fire with it, or uranium might've just been another stone before we discovered nuclear sciences. In that sense, we can indeed "create" new resources.
I.e. we might get ever closer to a world which is sustainable in the sense that humanity doesn't live off limited resources anymore (say, using machines to convert solar power to food more directly than using plants), but where most of nature has been destroyed and hence the possibilities for recovering by falling back to (even temporarily) using reserves increasingly vanishes (no place to build cheap or simple housing anymore, no land or even suitable climate to fall back on using plants as food). Thus all sorts of small crises can each lead to a lot of dying (perhaps like today's famines in Africa, but now all over the world).
But you may know more than me and your point may well be true. (I'm not a researcher, just fantasizing. I should get some experience in mathematical modeling.)
World population is not going to reach 100 billion in the next 200 years.
New technologies may allow:
1) Grow food in cold climate (Russia, Canada and even Antarctica).
2) Grow food in the ocean.
3) Grow food under ground.
4) 10x+ increase in food output from the same amount of land.
5) Industrial food synthesizing.
Needs an energy source
> Grow food in the ocean.
We already do this and we call it fish. We're also terribly bad at managing this very important resource.
> Grow food under ground.
Needs an energy source
> 10x+ increase in food output from the same amount of land.
Needs wildly fantastic breakthrough in practice, currently at odds with the theoretical maximum yield from acreage.
> Industrial food synthesizing.
We already do quite a bit of this but you'd have to come from an entirely different angle (such as synthesizing protein from non-biological sources, currently not a possibility).
So, with present technology and present knowledge about energy budgets and support capabilities of arable land it's as far as I can see right out.
If there is some totally out-of-the-blue breakthrough (such as atomic synthesis of arbitrary compounds combined with free energy) then sure, anything is possible. But that's the same kind of bet the cryonists (sp?) make, or even some religions, once you allow for miracles the future possibilities are limitless.
I'll be more than happy to concede that there will be improvements in yield but the amount of sunlight falling on an acre of land and the available minerals and precipitation are limiting factors, even when you factor in greenhouses, artificial lights, irrigation and so on. Hydroponics is probably eventually one of the most efficient ways of doing all this and even that has fairly hard limits in terms of energy required and amount of nutrients and water required.
Sun. Fission. Fusion.
> you'd have to come from an entirely different angle
Not me personally, but tens of billions of new people who would be born in the next couple of hundred thousand years.
> If there is some totally out-of-the-blue breakthrough
If in 1900-2000 food production increased 5x then it is reasonable to expect that in the next 100 years food production may increase 5x again (or more if needed).
It looks like you want to have enough food now (in 2015) in order to be able to feed world's population in 2215.
Why do you need to have that food 200 years ahead of the actual demand?
The problem isn't feeding and housing people, it's flying them to Greece for a weekend vacation, buying an endless supply of electronic and motorized consumer products, and a race-to-the-bottom attitude with power generation in the developing world.
Science could change that very fast: birth control isn't available to everyone on earth... yet. But religion could change that fast too.
So I guess estimates for the earth population will depend on both science and religion more than anything.
The population of both the us and w.europe is growing. (Immigration)
Simple: because you believe your (religion, parenting skills, values, heritable traits) are the best. Having a dozen kids per family is a leading way to innundate society with whatever you think is awesome.
Maybe the estimates of Malthus were wrong, but the underlying concern is still correct. Our current food production is not sustainable because it relies on non-renewable energy sources. I don't claim no solution can be found for that, but there is also no reason to believe there will be a solution.
Another way to look at it makes it very plain: the surface area of earth certainly is limited. So if population would grow forever, we would reach a point where every person would only have one square foot of ground to live on.
Even that might be doable - we could live in a stacked way (skyscrapers), or Matrix-Style in coffins with virtual environment. Nevertheless it doesn't seem like a very desirable future.
The inference is painfully obvious: for most of history, China has been populated at its own carrying capacity. The fact that the limit was broken (really, raised) a few times doesn't mean the limit isn't a worthy concept.
My immodest proposal is to introduce a natural decline in human populations to more easily sustainable levels via the introduction of a reproductive "right": every individual when born is entitled to one child.
A couple, then, could have a family with two children. Those who aren't interested in having children could sell their "right" off on a market to people who want to have more than their one child individually, so a couple could buy the rights to more children and a larger family from those who don't want to have children. The market could even fractionalize/derivatize those rights so that individuals could sell "half" a childbirth right and two of those individuals could have a family with one child.
The best part is, at two children per two parents, it's lower than the replacement rate of "2.1" which means population levels would humanely decrease with no need for wars or murder.
Our current societies are predicated on larger youth populations than parent populations to support us in our old ages, but this strategy combined with robotic technology for the elderly and post-scarcity economics would free us from that pyramid scheme. This helps support a basic-income type scenario for those people who assume that everyone (or 'THOSE PEOPLE') living in our society will just have tons of kids due to boredom. Like the fears trotted out about "welfare queens" having tons of kids because they supposedly get "free stuff."
The disadvantage is the dubious assumption of inevitable resource scarcity. If resource scarcity has yet to become a major problem, and may not in the foreseeable future, why impose population limits?
"Globally, total fertility is expected to fall from 2.5 children per woman in 2010-2015 to 2.25 in 2045-2050 and to 2.0 in 2095-2100 according to the medium-variant projection. However, in Europe and Northern America, total fertility is projected to increase between 2010-2015 and 2045-5050 from 1.6 to 1.8 children per woman in Europe and from 1.86 to 1.9 children per woman in Northern America. In Africa, Asia, Latin America and the Caribbean, and Oceania, fertility is expected to fall between 2010-2015 and 2045-2050, with the largest reductions projected to occur in Africa. Thus, in all major areas of the world, fertility levels are projected to converge to a level at or just below the replacement level by 2095-2100"
http://esa.un.org/unpd/wpp/Publications/Files/Key_Findings_W...
http://www.gapminder.org/videos/dont-panic-the-facts-about-p...
http://www.gapminder.org/news/world-peak-number-of-children-...
Still, it surprises me overpopulation fears are so commonly expressed. Seems like a greatly overblown meme that will end up doing more harm than good. Much like Malthus opposing projects to feed the poor and hungry, I sometimes hear people going as far as saying we (meaning relatively wealthy, white Americans) should just "let them die" when it comes to impoverished people all over the world. Despite the fact that, if energy consumption and environmental damage is the fear, people in industrialized countries use as many resources as dozens, hundreds, maybe thousands of lives in the "developing" world.
The world could likely support orders of magnitude more people than we give it credit for. We haven't even started harnessing materials from space industry, space-based solar power, or using the oceans and seabed as living space. There's another 70% of the Earth's surface that hasn't even been touched yet, and that percentage grows even more when you consider the vertical spaces available within it. The overpopulation meme seems more dangerous to global welfare than actual overpopulation has ever been thus far.
Kevin Kelly's edge.org response is a good read on the entire overpopulation issue: http://edge.org/response-detail/23722
[1] https://en.wikipedia.org/wiki/List_of_cities_by_population_d...
2) If there's no specific advantage to a lower or stable population, why is any particular number preferable to another?
3) There are lots of advantages of large population: larger communities for people with low-frequency deviations from social norms, a broader spectrum of human social and psychological possibilities represented, increased production and creative capacity, greater base of working-age citizens to support the non-working portion (retired, children), more people at the top of the bell curve to draw from for important positions (better leaders, more geniuses, etc)... This is not an exhaustive list.
4) Likely other advantages as well, which would seem to counter the disadvantages of larger population, judging from past human history (and assuming no weird non-linear relationships). If the world is better with fewer people, would you want to go back and live in a world with only 100,000? 1,000,000? Some other specific number?
2. There are of course advantages to stable population sizes, most importantly resources will last longer and allow sustaining human society for longer.
3.1. larger communities for people with low-frequency deviations from social norms
It is not obvious to me why that is a good thing.
3.2. a broader spectrum of human social and psychological possibilities represented, increased production and creative capacity
That seems to be the best argument for larger populations besides increased production capacity because that is countered by an increased consumption.
3.3. greater base of working-age citizens to support the non-working portion (retired, children)
That is not true for a larger population, the proportion is the same as for a smaller one. It is only true while the population is growing and that is either unsustainable or the effect is unimportant if the growth is marginal.
3.4. more people at the top of the bell curve to draw from for important positions (better leaders, more geniuses, etc)
That is essentially the same argument as 3.2.
4. Smaller populations are not necessarily better, you benefit from decision of labor, scale effects, you are more resistant to disasters. The optimum is definitely somewhere in the middle, it is neither one human that can no longer reproduce and will easily go extinct, and it is also not ten to the hundred for obvious reasons. The question is therefore definitely not whether or not we should seek for a stable population, it is where the most desirable level is.
And here I argue we should first bring the entire world population to the levels of wealth, education and consumption of the middle class of leading developed countries and then we can have a look at how much resources are left, what happened to environment and climate, whether we need more smart people.
Then nothing is.
Fortunately for those of us who don't want to see humanity ruled as you suggest, it seems pretty well established that reproduction is a fundamental human right.
So if the population grows to some level that becomes a danger for the sustainability of our society, then it is in everyone's self-interest or the interests of their children to voluntarily limit the number of children they have. And if the majority of the people agrees on that, then having more children than the society believes you should have becomes a punishable misbehavior.
So right now you can imagine to have the right to reproduce but that is only because we did not yet have the need to regulate it because the population is not yet too large. But there is absolutely nothing that makes this an eternal truth. Once the population reaches a critical level you face the decisions to either limit reproduction or to see your children live a miserable life in an overcrowded world. I would definitely vote for limiting reproduction because I value my few children having a good life way more than having many children having a miserable life.
And this has nothing to do with being ruled in one way or another, the society itself should come to the conclusion that it is a necessary policy.
Where are those rights coming from? And do they only apply to humans? Why? Why not to primates? If they apply also to primates, are lions hunting and killing primates - not sure if they actually do - violating basic primate rights? How do you come to know about your fundamental rights? Could you still come up with the same ideas if you were the only human on earth?
And more specifically, if reproduction is a fundamental right, can you rape other humans in case no one voluntarily wants to reproduce with you? You probably don't think that, so you are not really arguing for an ultimate right to reproduce but the right to do so with consent. This again raises the question of incest. Why can we outlaw incest when you have a fundamental right to reproduce. Because bad things are likely to happen to possible offspring? But so does reproduction leading to overpopulation just not in such a direct way.
Absolute rights and a right to reproduce in particular are - at least in my opinion - hard to defend positions. The only more or less reasonable argument I can think of is declaring that those absolute rights are a god given thing and period. In that case there is not much I could argue against besides the believe in a god in the first place.
> Reproductive rights began to develop as a subset of human rights at the United Nation's 1968 International Conference on Human Rights.[4] The resulting non binding Proclamation of Teheran was the first international document to recognize one of these rights when it stated that: "Parents have a basic human right to determine freely and responsibly the number and the spacing of their children."
To answer your question of where those rights come, they come from a international agreement that these principles should be the guide to a human and humane culture. More about this is available from https://en.wikipedia.org/wiki/Natural_and_legal_rights . I think it's best to consider this a moral philosophy that exists only as part of a consensual reality.
Regarding animal rights, there is less agreement on a framework for how to handle those. Animals cannot enter into a social charter, and it is difficult for them to voice objection about mistreatment. Most about this is available from https://en.wikipedia.org/wiki/Animal_rights .
> "Why can we outlaw incest when you have a fundamental right to reproduce."
These rights are not absolutes but exist in tension. While we have agreed that there is a fundamental right to free speech, time, place and manner restrictions are allowed. While we have agreed that there is freedom of movement, such freedom may be limited in times of quarantine.
Thus, simply pointing out that there is a restriction on the right of reproduction does not make it less of a right than the rights of movement and of free speech.
> if reproduction is a fundamental right, can you rape other humans
ryanwaggoner was likely being brief on the expectation that you could do some research yourself and determine that 'Reproduction is a natural right' is a short-hand for a more lengthy and nuanced definition. Quoting now from the Cairo Programme of Action at https://en.wikipedia.org/wiki/Reproductive_rights#Cairo_Prog... :
> Reproductive health is a state of complete physical, mental and social well-being and not merely the absence of disease or infirmity, in all matters relating to the reproductive system and its functions and processes. Reproductive health therefore implies that people are able to have a satisfying and safe sex life and that they have the capability to reproduce and the freedom to decide if, when and how often to do so.
You can see that the 'freedom to decide if, when and how often to do so' includes all participants. Thus, rape is not part of the right to reproduce, as it is generally understood.
Rape is also in tension with other rights, such as the right to free association.
> "... absolute rights are a god given thing and period"
Humans created all the gods. Therefore humans can create human rights.
> "Could you still come up with the same ideas if you were the only human on earth?"
Human rights guide how humans should be treated. If I were the only human on earth, there would be no need for the moral philosophy of human rights, just like there would be no need for thespian, oratory, or square dancing knowledge. I doubt I would be clever enough to come up with those ideas on my own.
I am not sure whether you intended it this way but in my view your comment supports that position because you are mentioning pretty recent conventions, tensions between rights and so on. I see nothing in your comment that is incompatible with imposing restrictions on reproduction if this is deemed necessary to sustain a healthy human society.
And I didn't want to discuss animal rights and the other things I mentioned, I only wanted to provoke some thoughts about related things in the hope to inspire the insight that rights are very different from physical laws insofar that we humans make them up to achieve behaviors and outcomes we deem desirable, that they are not given eternal truths.
Exactly. And no one with experience on the topic means that when they talk about natural rights, so you are misinterpreting qrendel's statement "Reproduction is a natural right."
qrendel is clearly wrong about population dynamics, as 'greater base of working-age citizens to support the non-working portion (retired, children)' only applies for an exponentially growing population, which must stop at some point, for clearly physical reasons like the Sun not providing enough energy.
qrendel also prefers city life, as seen in the assumption that the presence of more people means that those with uncommon interests "will be able to form communities of people with similar interests". This view excludes those who want to go for long walks alone on the beach, or hate living where they can see the lights of their neighbors, or want the local ecosystem to continue to support wildlife that does poorly around dense human habitation.
As qrendel does not believe there is resource scarcity, than that's only because qrendel does not regard things like '5 million wild buffalo freely roaming the US plains' or 'ability to see the Milky Way in the night sky' as resources. These are certainly not critical to what's needed for the human body to survive, but survival is only the bottom of Maslow's hierarchy of needs.
Despite those wrong statements, and incorrect generalization, I cannot tell from what qrendel wrote if "natural right" is used as something other than how it's generally used. However, it is possible to have both reproductive rights and a stable population, as we see in many of the countries which are below the replacement level of fertility, so these are not in direct opposition.
When you said 'Reproduction is not a natural right', I think you meant to say 'population growth to resource limits is not a natural right'. I and (it appears) ryanwaggoner were thrown off by your use of qrendel's phrase with your interpretation of what qrendel meant.
Stabilizing population at a limited number would presumably be done indefinitely, not for a brief period and then removed. Therefore natural selection would have time to take effect. It obviously has not since the institution of the one child policy or the development of birth control, which were recent developments on an evolutionary timescale.
> only applies for an exponentially growing population, which must stop at some point, for clearly physical reasons like the Sun not providing enough energy.
This discussion keeps going back and forth between needing to implement population controls now, or sometime in the foreseeable future, versus the fact that the entire Hubble volume of the universe likely has some total carrying capacity. Saying that even something like a Dyson sphere surrounding the sun would only provide finite energy is not a valid reason for population controls here and now.
> prefers city life
Not really, but preferences aside, most living apart from civilization still benefit from a larger civilization to support their needs. Some may prefer to "live off the land" with no technology, but even those living the quiet life can still enjoy things like advanced medical care or a broader range of products and services delivered to them, if they so choose. Population doesn't remove any possibility of quiet walks in nature or ability to see a starry sky at night, though would perhaps make them a scarcer resources. They are, for example, still available to people now, despite a world population of over seven billion. The fact that in some distant future unbounded population growth would lead people to outnumber the number of atoms in the universe isn't a remotely relevant consideration towards whether implement population controls soon.
Again, evolution does not work that way. Evolution doesn't care if a species goes extinct because it doesn't breed enough.
Plus, consider a 1% growth rate per year. In 1,000 years the population will increase over 20,000-fold. With 0.05% growth it takes a bit under 2,000 years for the same growth. But 2,000 years is nowhere near enough for evolution to influence humans.
> not a valid reason for population controls here and now
I never said it was. Not only that, I say that they were not incompatible, and used as my examples the many counties with full reproductive rights and a birth rate which is below what's needed for replacement and which don't have population controls.
> though would perhaps make them a scarcer resources
Yes, that's exactly my point. I'm glad you agree that these are scare resources.
> They are, for example, still available to people now, despite a world population of over seven billion.
No. Some of these scare resources are gone.
I gave one example, our buffalo resources which once numbered it the millions. You probably rejected it out of hand, but that's because you grew up in a culture which doesn't have it. But the US destroyed that resource in part to destroy the way of life for the Plains Indians, and open up the Plains for the expansion of the predominately white population with a very different culture.
You are repeating the same paternalism when you write "most living apart from civilization still benefit from a larger civilization to support their needs."
Who are you to say that everyone must live with that tradeoff? What ways of life will you want destroyed to support the 1000x large population you urge on us?
Rate of evolutionary change depends on the selection pressures on the allele in question. There are formulas for calculating both the probability a mutant allele goes to fixation[1] as well as the expected number of generations for it to do so[2]. With high selective pressures evolution on the scale of a few thousand years is certainly possible - the time taken for lactase persistence to develop in humans is estimated at around 3,000 years.[3] In the extreme case, if all individuals lacking a given dominant allele are removed from the population, it would only take a single generation. So, no. Though I admit the number of generations does increase with the natural log of the population size, so it would take longer with greater population sizes.
[1] http://www.biology.arizona.edu/biomath/tutorials/application...
[2] https://books.google.com/books?id=2zVqBgAAQBAJ&pg=PA466&lpg=...
[3] https://en.wikipedia.org/wiki/Lactase_persistence#Evolutiona...
Buffalo - Current population estimates are around 500,000 in the US. Given that large herds of protected buffalo and many locations with low light pollution still exist, you've failed to provide any examples of experiences that are forever gone.
Of course some situation can always be constructed. You can't find 20-30 million buffalo anymore, just as extinct animals are gone (ignoring current work by George Church and others on de-extinction), just as no two people can simultaneously be the US President or first man on the moon. Some particular version of experiences are constantly being made unavailable, and that's a fact of life regardless of population.
As for the Plains Indians, I don't think that genocide was caused by overpopulation so much as the US government's desire for westward expansion. Sure, it might not have happened if the population had stayed much smaller, but those aren't the only two possible outcomes. It's not as if resource availability had been exhausted in the east.
Aside from that, if you go back and read, you'll see my claim was that there are advantages to larger population, not that it was necessarily a moral imperative. (The only argument for it as a moral imperative I can think of would rely on the assumption that future unborn lives should have moral relevance to us now.) Even if I were arguing that claim, it would be equally paternalistic for one to dictate what state the world should be in simply to protect experiences they prefer.
Like I said, you do not understand evolution.
Yes, I know about the short timescale for lactase persistence. You'll note that it's two mutations.
Now you need to demonstrate that "increased desire to reproduce" is something that 1) is directly traceable to genetics, 2) is only a few mutations away, and 3) the intermediate forms lead to better evolutionary advantage. All you have is an unfounded belief.
From a paleobiology perspective, human population was stable for a much longer time than this relatively recent exponential expansion phase. If there were such thing as a genetic imperative pushing humans towards higher fecundity, it would have occurred long ago.
> Buffalo
This is why I said millions, not 500,000. You'll notice that there are no Plains Indians living as they once did.
> Some particular version of experiences are constantly being made unavailable
Yes. And who are you to say that your belief in exponential population growth gets priority over the experiences that others want to have?
> I don't think that genocide was caused by overpopulation so much as the US government's desire for westward expansion
Interesting how you managed to decouple population pressure and western expansion. (Note that I don't say "overpopulation" but "population pressure".) Do you think the following summaries are wrong?
"With the Louisiana Purchase and subsequent land acquisitions, U.S. territory grew exponentially in the first half of the 19th century. Populations huddled on the east coast saw grand opportunities to move into more expansive areas where land was cheap and more arable than it was back east, particularly in New England." - http://www.ask.com/history/were-reasons-westward-expansion-9...
"As the population of the original 13 Colonies grew and the U.S. economy developed, the desire and attempts to expand into new land increased" - http://www.pbs.org/kera/usmexicanwar/prelude/md_introduction...
"In order to grow, the capitalistic economy and republican form of government needed surplus land and abundant natural resources such as wood, fossil fuels, minerals, and water. Many feared that without a surplus the parceling of limited resources to a growing population would eventually lead to class conflict. Not everyone embraced this philosophy." - http://www.encyclopedia.com/doc/1G2-3406401030.html
"The most important forces [in the westward expansion] are population growth and the decrease in transportation costs," Vandenbroucke said. "Population growth is mostly responsible for the investment in productive land - without it less than half of the land accumulated in 1900 would have been accumulated." - http://www.eurekalert.org/pub_releases/2008-02/uosc-wcw02280...
Or this quote regarding Manifest Destiny, from https://en.wikipedia.org/wiki/Manifest_destiny :
> The United States, while intending never to acquire lands from the Indians otherwise than peaceably, and with their free consent, are fully determined, in that manner, progressively, and in proportion as their growing population may require, to reclaim from the state of nature, and to bring into cultivation every portion of the territory contained within their acknowl...
A pointless and inflammatory statement that you had, in fact, not made up until this point. This is getting ridiculous, and sidetracking from the original discussion on the viability or necessity of population controls.
This discussion seems to have been reduced to your assumption that there exists no series of favorable mutations which lead to increased desire to reproduce or to circumvent population controls. You know as well as I do that it is infeasible for me to give you an exact list of mutations which will affect biochemical pathways in such a way to as dictate the outcome of reproductive behavior, just as it is infeasible for you to show that no such series of mutations exists. This would include, among other things, no mutations affecting psychological attitudes regarding children, effectiveness of various birth control methods, or the balance of desire for sexual intercourse against other biological imperatives, and despite changes in external environment and other selection pressures.
Your argument could as well be used to argue against evolution entirely, since there are plenty of biological traits across species for which the exact series of favorable mutations that lead to them is not known. This is basically a claim that you will not believe evolution towards a specific outcome is possible unless you are shown the exact series of favorable mutations that maintain stable biochemical pathways in the organism the entire way. If you really believe that genetic changes affecting reproductive behavior are that unlikely, or that humans have already maximized such things despite major and recent environmental changes to selection pressures such as the introduction of birth control are so unlikely as to be effectively impossible, that's your own belief which I doubt you have any extensive evidence to support.
I really doubt that I am the one with a poor understanding of evolution here, but since this has been reduced to a basic difference of opinion about the likelihood of an occurrence (development of mutations favoring the particular outcome) that neither of us seems able to quantify, I see little reason to continue. This seems to be the fundamental disagreement here.
> Do you think the following summaries are wrong?
My claim was that those were not the only two possible outcomes, meaning genocide of the Native Americans versus a Malthusian population collapse amongst the settlers. The expansion west at the expense of native peoples was also due to the fact they devalued the lives of Native Americans relative to their own desire for expansion. Why inhabit smaller territory when you can claim more at the expense of the lives of others you do not value? Had the value of human life been greater to them than the value of the land they stole, the expansion would not have proceeded as it did.
What is the relevance of the genocide of the Native Americans to the original discussion? This was about reasons for continuing population growth versus stabilizing it, which led to whether reproduction is a natural right, and what the advantages of larger population are.
If you think population growth has led to genocide throughout history, and will continue to do so in the future, you must be arguing against the agricultural revolution entirely (some do think the agriculture was a net negative, e.g. Jared Diamond). Population controls should have been imposed in the ancient past and the world's population is already too large. That would negate most of the advances made by civilization since then, as well as all the cultural processes and technologies that can only be sustained by a larger civilization. It would also certainly be an attempt to impose your judgment about superior ways of life onto the rest of the world.
I'm fairly skeptical that's actually your claim, though. If this is going to continue, I'd really rather refocus on the original discussion, regarding the pros vs. cons of larger populations or the ne...
3.2. Contradicts the basic premise (no immediate resource limit) and the original article. The world has become richer despite growing population, because production has outrun consumption. No reason to think it will stop in the immediate future, any more than it did in Malthus' time.
3.3. You're simultaneously saying the economic problems arise when population stops growing and becomes stable, and supporting ending population growth in favor of a stable population. If there's a limit where quality of life decreases due to increasing population, we haven't hit it yet, given that quality of life and per capita wealth is still improving globally, so there's no reason to put the brakes on before we even know where it is.
> it is also not ten to the hundred for obvious reasons.
We're assuming technology and productive capacity also improves to keep up. We're also nowhere near 10^100. Nor do we know where this hypothetical optimum is. Population controls should be a last resort to solving problems we are't facing yet, not done just because a theoretical optimum for quality of life may exist at some hypothetical large number.
3.2. I would argue that the increase in wealth is mostly due to increased productivity and not due to population growth and therefore could continue even without further population growth. Population growth is certainly not totally irrelevant due to scale effects but I don't see that simply doubling the population would lead to significantly increased wealth.
3.3. That is not what I am saying. Having a pyramid shaped age structure is an easy way to have a lot of workforce available to support the elderly but that structure is not the result of a large population but of an growing population. And in order to be a significant effect you can not have just a tiny bit of growth but a substantial amount of growth is definitely unsustainable.
The limit definitely exists but I also think we will not hit it, we will not need any (large scale) birth control policies because the birth rate will drop enough with increasing wealth. Looking at developed nations it looks actually more like we will have to incentivize having more children in order not to go extinct.
Basically the argument that Malthus was wrong and thus we shouldn't worry about overpopulation is the same as ignoring upcoming problems and saying that we will solve them when they will come up.
We as humans can solve problems but sometimes we're destroying much in the process, we're not fast enough or it's even just not possible. There have been numerous catastrophes and downfalls in human history and the amount of nature we destructed is extreme.
Maybe we can have orders of magnitude (10 billion, 100 billion) people living on this planet, but the question is whether it would still be livable, especially without nature.