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Each of us can look towards the sky and see the sprawling space and resources available.

Except there isn't a sprawling amount of resources for an exponentially growing population. Let's say we reach the resource limit of Earth and start reaching for the stars to find new places to live. If we can colonize one Earth-like planet around every single star of the 400 billion stars in the Milky Way, we would run out of places to live after 2685 years if the human population kept growing at a rate of 1 % per year. That isn't even enough time to reach all places in the Milky Way even if we could travel at the speed of light. Actually you could barely cross 2 % of the diameter of the Milky Way in that time. Exponential growth is unsustainable. Period.

You are conflating the message with the example given. The point is simply this; some are too eager to solve resource contention issues via population reduction, which is not at all stimulating nor is it innovative. It is the lazy way out, and should really be a last resort or option. I do appreciate your point, but I would like people to be less eager to buy into population control. Encouraging alternative solutions instead; innovations of efficiency, waste reduction, or inventions which are more preferable than population control.

There is a growing group of people who believe the world is over populated. I want to push back against that mentality a little bit, because we should not resign ourselves to hopeless thinking. There are plenty of things we can do to improve our situation before resorting to dramatic actions. I want to avoid "there is no other solution" like thinking. Once we stop looking for other solutions, it will become a self-fulfilling prophecy. That is what I mean by lazy and morally hazardous.

But there are no other solutions, believing that technical advances can keep exponentially growing resource demands in check is delusional. If some process is currently 20 % efficient then there is at most a factor of 5 to be gained. And that assumes 100 % efficiency is attainable to begin with while it is not unlikely that physics sets a limit on the maximum attainable efficiency of say 50 % or 80 %. A population growth rate of 1 % per year will eat up a factor of 2 in improved efficiency in 70 years and there are only so many times you can squeeze out another factor of 2 before you hit a hard limit.

It is not lazy to try to control population growth, it is the only viable longterm solution because technology can not solve this problem. The goal must be to stop population growth or, for practical matters, increase the doubling time at least to the order of millennia. That is why I gave the example with colonizing the Milky Way, to make clear how bad the problem is and how infeasible technological solutions are.

I guess another obvious point is: there isn't a question of whether population growth will be controlled, it's more a question of how exactly that will happen. I.e., is it something we choose, or is it forced on us?

less desirable options: uncontrolled global civilisation collapse with rapid decline in living standards and population, nuclear war, etc

more desirable options: intentionally adjusting lifestyle / affluence in western countries, non-coercive methods of population control (e.g. better healthcare, increased access to family planning, increased opportunities for women to participate in education / economic activity, etc), less focus on short-term appropriation of wealth

I wanted to mention this, too, but then decided to keep it short. Actually I think population control is not really necessary because many parts of the world have already reached sustainable fertility rates - or non-sustainable fertility rates in the other direction - due to human development. And I don't see why regions with fertility rates above 2.1, especially Africa, would not follow that path assuming we manage to shrink the development gap.

One could ponder whether it would make sense to use population control in addition to improved technology and development to make the ride across the world population peak smoother, to make the peak lower and happen earlier. There would almost certainly be at least some benefits to this, but given how long political debates about that would probably take, never mind implementing and enforcing the decisions, there might actually not be enough time to do this and get some noticeable impact out of it.

As long as it looks like the world population will peak around the end of the century, go for technology to make it as pleasant as possible, but if the outlook indicates that the world population does not peak or at least stabilize in the foreseeable future, then population control is really the only way or it will become pretty unpleasant as you indicated in your first scenario.

Reminds me of the scene in The Matrix where agent Smith tells Morpheus that humans are like a virus: they move to an area, and when all natural resources are consumed up they spread to another area.

I was thinking exactly the same thing. I think [one of] the critical problem[s] is that we continue to think through the lens of resource consumption until resources are exhausted. I think it'd be pretty interesting if we began seriously evaluating ideas through the lens of resource creation on some fronts, and denying resource consumption on other fronts. Of course, I don't believe this will be achievable while the world continues to celebrate and allow the capitalist modes of production and value extraction.

Is there a recognized exhaustable availability of resource X? Then we simply don't allow that resource to be used as a means of capitalist value extraction from a planet. The resources belong to the commons, and we must shift away from allowing profits to guide the use of raw materials.

I look at, say, the last century of the automobile, and cannot avoid wondering just how different our lives would be if we'd bypassed the idea of placing a couple tons of metals and plastics in everyone's driveways. What else might we have used those materials for, if we mandated that using them had to be done in a way that benefited a large number of people with the same material cost. This really goes for nearly every consumer product made available to the markets.

I don't think we'll be able to come up with viable long-term strategies for handling population growth, and providing a high quality of life to all members of that population, until we move beyond status-driven consumerism and the capitalist economies that create and depend on them.

> If we can colonize one Earth-like planet around every single star of the 400 billion stars in the Milky Way, we would run out of places to live after 2685 years if the human population kept growing at a rate of 1 % per year.

I'm obviously missing something in the figures you're using to calculate here, but how exactly would we consume all the galaxy's resources in < 3,000 years? We've been doing our thing on Earth for more than 3,000 years, and there are still resources available.

I'm not disputing that we consume far too many resources in a very irresponsible fashion. That just seems to me to be a very much higher rate of resource consumption than we've seen historically. Surely, if we were to develop the ability to colonize other planets, we wouldn't reproduce the same wasteful resource consumption patterns and history, because we'd have greater technology and, more importantly, improved philosophical outlooks on how we use those resources. Are you thinking we'd move 100% of the human population to each new planet and just set up the same wasteful shop we have till we exhausted the planet? I'd expect moving a smaller portion of the population to each new place, and setting up a far less wasteful colonization effort, that itself would continue to improve (hopefully).

The calculation presumes that at one point in time we will reach the carrying capacity of Earth. It makes no assumptions about when that happens, what the population is at that point or what technology is available at that point. It could happen because we run out of production space for food or that there are no longer enough plants to handle human carbon dioxide production, it could happen in 50 years with essentially the same technology as today or in 5000 years with very advanced technology, it could happen at 10 billion people or at 10 trillion people. But there is such a limit at which it becomes impossible to support more people on Earth - the ultimate limit is having so many people that the heat produced by the bodies alone raises the temperature to the point that humans can no longer exist.

With a population growth rate of 1 % per year the population doubles every 70 years. 2685 years are about 39 doubling periods which means that the population will increase by a factor of 549,755,813,888 over this time and if we needed on Earth at the beginning we then need that many Earth-like planets or the entire Milky Way under my assumptions of 400 billion stars and one inhabitable Earth-like planet per star. This assumes no further or at least only negligible technology advances over those 2685 years, i.e. we do on the new planets what we did on Earth when the carrying capacity of Earth was reached, but which we assumed was the best thing possible at that point in time.

Exponential growth is really that bad and 1 % per year is a pretty high growth rate. We could never have sustained such a growth rate for extended periods. We only surpassed 1 % per year in the early 20th century, before that it was a lot lower. My entire point was to demonstrate that exponential growth with 1 % per year is so huge that it would grow beyond any realistic resource limits in pretty short time. Decreasing the growth rate by a factor of 10 to 0.1 % per year will only increase the doubling time by about a factor of 10 and we would still reach the carrying capacity of the Milky Way in relatively short 26,728 years. Stabilizing the population at some point is really the only option, exponential growth can not possibly work besides with growth rates that are essentially zero.

...an exponentially growing population.

Which population is that? Certainly not humans.

Of course humans [1][2]. With a few exceptions the population increased by some factor every year for thousands of years. The factor was admittedly small for long times, 0.1 % per year since 1000 BCE and even smaller before, but the factor increased over time and surpassed 1 % per year in the early 20th century. So depending on the reference point the population growth can even be considered superexponential. And while a growth factor of 0.1 % per years seems pretty small at first, it only increases the doubling time by a factor of 10 from 70 years to 700 years.

[1] http://history.stackexchange.com/questions/17465/yearly-popu...

[2] http://faculty.econ.ucdavis.edu/faculty/gclark/210a/readings...

The UN chart at the first Google result [0] seems to indicate a negative second derivative. This would imply that human population, like all other populations of all other organisms, exhibits logistic, not exponential, growth. Of course, portions of logistic charts can appear exponential.

[0] http://news.nationalgeographic.com/news/2014/09/140918-popul...

The population growth rate peaked in 1962 at 2.2 % per year and is now back to 1.1 % per year. There is no way for a population to grow exponentially for a long time, the growth will hit some resource constraint sooner or later and then the growth stops. Therefore also the human population can not and will not grow exponentially forever. But the important point is that you don't want to get stopped by hitting a resource constraint, that is always going to be an unpleasant experience. And the slowdown of the growth of the human population is not due to hitting a resource constraint as it happens in animal populations, it is because of a conscious decision to have less children and having the means to do that. And that's a good thing.

Sure, the demographic transition is a benefit to humanity, and we've seen enough of it to know that while the timing might vary it will eventually happen everywhere, and certainly by the end of this century. Since we agree, I guess I don't know why the supposedly-but-actually-not exponential nature of human population growth was ever mentioned in the first place.

My first comment was meant as an argument that technological advances can not be a substitute for preventing an unchecked population growth, but the comment did a bad job expressing this. A bit down the thread is another comment making things a bit more clear. I also think it is not a clear-cut issue, in some sense we are actively doing population growth control when we promote birth control. The motivation may primarily come from other reasons like avoiding sexually transmitted diseases and not necessarily to avoid overpopulation, but at least in some regions population growth control is part of the motivation.

And, because you mentioned the end of the century, there is still »The Limits to Growth« and it predictions. I am actually not sure on which side I am here. I can't really imagine a collapse of society as we know it in the second half of the century but I am also aware of the sudden and unexpected behavior of complex systems and how hard it is to counteract a system with a lot of inertia. But if the predications come true, population control may become an issue sooner than we like.

'Exponential' may be a bit of a stretch, but world population does appear to be growing rapidly. We've grown from 3 billion people in 1960 to 7 billion people in 2012, I'd consider that to be fairly rapid:

http://www.google.co.uk/search?q=human+population+growth&prm...

Arguing for population reduction isn't lazy. Arguing against it by throwing a bunch of loaded language at it while never presenting an actual counterargument definitely is lazy, though.

The moment you describe it as "slaughter," you've completely lost me. A gradual reduction by having children at below replacement rate isn't "slaughter" and doesn't in any way imply that future generations are somehow bad or unwanted.

If population reduction really is such a bad idea, you should be able to come up with much better arguments against it.

It isn't helpful to myopically discuss population and ignore other things like environmental limits, affluence, resource intensity, biodiversity, (in)equality, etc.

Similarly, it is not helpful to decree that any discussion of population is tabu.

Other societies have very different standards of what is morally normal and acceptable when it comes to population growth.

E.g. Jared Diamond's book Collapse discusses the island of Tikopia [1] -- the people living on this isolated island (~1200 people on 5km^2 of land) managed to live sustainably for hundreds of years with a stable population:

> Most readers of this book will have practiced one or more of those methods [of population regulation], such as contraception or abortion, and our decisions to do so may have been implicitly influenced by considerations of human population pressure or family resources.

> On Tikopia, however, people are explicit in saying that their motive for contraception and other regulatory behaviours is to prevent the island from becoming overpopulated, and to prevent the family from having more children than the family's land could support.

Traditional methods of regulating population included: contraception, abortion, infanticide, celibacy of younger sons and "surplus" marriageable women, suicide, "virtual suicide" (setting out on dangerous sea voyages with essentially no hope of survival), and one instance of warfare between clans (after a decrease of fish and shellfish population led to starvation and conflict over the remaining land and coastline).

> Most of these seven methods for keeping Tikopia's population constant have disappeared or declined under European influence during the 20th century. The British colonial government of the Solomons forbade sea voyaging and warfare, while Christian missions preached against abortion, infanticide, and suicide. As a result, Tikopia's population grew from its 1929 level of 1,278 people to 1,758 people by 1952, when two destructive cyclones within the span of 13 months destroyed half of Tikopia's crops and caused widespread famine.

> We already have hints from various nations who have tried to control populations, with evidence of detrimental and unintended side-effects.

Some might argue it did help China. I'm curious what examples you are thinking of (citation) besides obvious genocide and murdering.

> I am by no means saying there are simple fixes. But immediately jumping to population control is pure lazy thinking.

There is nothing wrong with a nation having sensible mild restrictions or tax relief for taking up less resources. We tax tobacco, liquor and gasoline. Hell red meat should probably be taxed as well (one could argue liquor is not as bad for you as cow and for sure cow is worse on the environment). It doesn't have to be draconian for a mild behavior changes.

As with dietary weight loss real changes can be made with out being that innovative or being that extreme. Some might even say the lazy (your word) thing is reaching for the latest panacea instead of being disciplined and/or consistent.

BTW in nature many animals deal with population control with given limited resources (some nasty and some just not producing as much offspring). Probably a genetic trait to avoid extinction.

I completely agree on the intellectual laziness on exhibit with population reduction arguments. I think there's far more room for exciting creativity in thinking of ways to move humanity away from capitalist consumerism toward resource consumption habits that are fueled by a long-term outlook on how to avoid waste for the sake of making a buck (or a few billions of bucks), and how to put our creative efforts to use for maximizing utility of resource usage—all while continuing to improve the quality of life that everyone enjoys.

Just to add, since it seems to be ignored by proponents of population control, that if regulating life is actually being suggested with a straight face as moral, well, what's good for the goose is good for the gander, and you should really expect your own freedoms to be targeted in kind. It's an arguement that shoots the maker in the foot, and yet it keeps being offered outside of a punchline. I think it can only reflect a deep misanthropy in many people. Human presence on Earth is nowhere near unsustainable IMO - but even if it provably were, surely it would be better to starve than to cannibalize our own species' self-determination and in turn, our own.