>

So op took  an economics class and somehow ignored the fact that it’s not a population  crisis but age demographic crisis
Population decline by itself isn't a bad thing. The rate of population decline is what is worrying. 
I live in a country that had just under 4.8 million people 30 years ago. According to last year census, we are just above 3,8 million now. By the end of this century we will be perhaps below 2 million. Whatever your political views, the idea that that sort of population decline wont have negative effects on the country and society is completely delusional.
And we are not an exception. Developed countries around the planet are going to have rapid population decline in coming decades.

Innovation comes from a well educated population. Not from a large population. 

If you live on a planet that has a bunch of old people, instead of young people, that means that a greater proportion of money and resources that would have otherwise been spent on education or innovations now has to go towards medical care for the old. Which means less innovation. 
Also. All other things being equal, would a planet with a million people or 10 billion people have more innovation ? The answer is obviously 10 billion. Larger well educated population will have more innovation than a smaller well educated population. Didn't think that was controversial. >


All other things being equal, would a planet with a million people or 10 billion people have more innovation ? The answer is obviously 10 billion. Larger well educated population will have more innovation than a smaller well educated population. Didn't think that was controversial.

The controversial part is where you need to gamble on those 10 billion people always being able to find technology that will save the day. Because if they don't, we are doomed.
On the other hand, if the planet only had 1 million, carbon emissions would be drastically reduced beyond our wildest dreams, and there would be plenty of resources for all. >



On the other hand, if the planet only had 1 million, carbon emissions would be drastically reduced beyond our wildest dreams, and there would be plenty of resources for all.


As someone worried about carbon emissions, do you know what percentage of the atmosphere is carbon?  And what percentage is the ideal? >

It's not that there's a particular number that's ideal, and the problem is that we've stayed from that number. It's that it's changing so rapidly that it's snowballing faster than life in general, and human society specifically, can adapt on a large scale. If the global average temperature rose by 5°C over the next millennium, it probably wouldn't be too big a deal. But half that over the next 100 years is a very big deal.
I guess if i had to give you a direct answer, it would be approximately the amount that we've spent the last few millennia learning to live in. Decisions from that are fine as long as they happen slowly enough that we can adapt socially, and other species can adapt genetically, to the change. >

The atmosphere is currently 0.04% carbon.
Are you saying that 0.05% too much and 0.03% the ideal? Or is 0.04% the ideal?  What happens if it doubles and reaches 0.08%? Catastrophe? >

You're really glossing over the whole "lots of old people, very few young people" problem. >

Yeah, OP says “people should be saving money for retirement, so lots of old people being retired shouldn’t be a problem”
This is a fundamental misunderstanding of how the world and the economy works. It doesn’t matter how much money people have saved for retirement if there aren’t enough working people to make the stuff they need to buy with that money.
It isn’t like saving for retirement means you are saving cans of food to eat later, like you are a squirrel burying nuts for the winter. You are saving money that you hope to trade in the future to someone else for your food and basic needs. This will only work if there is someone to trade your money to; if society is full of old people who have saved up money for retirement and not very many young people to make the food and things, then you are just going to get rapid inflation as all these old retired people try to trade that money to a dwindling number of productive people.
If this is hard to understand, just imagine the extreme… what if ALL the people are old, and they have all saved a ton of money…. Who are they going to pay that money to? No one is making food, they are all sitting on their pile of money wanting to buy food. The money would be worthless. >

ALL the people won’t be, so such an extreme is absurd. reductio ad absurdum >

I wasn't claiming the extreme example would ever happen, I was trying to show why having fewer working age people would lead to problems by using a hypothetical case of having no working age people... sometimes it helps to see an abstract thing like that by imagining the extremes.
Also, that isn't what reductio ad absurdum means; it is a form of argument where you show that if your argument wasn't true, you would end up in an absurd situation. >

Your argument isn’t true, and you end up in a state of absurdity. >

That doesn’t follow at all. I was not arguing that we are in a world, or even headed to a world, where there are no working age people. That wasn’t my argument.
And even if my argument WAS absurd, it still isn’t a reductio ad absurdum. It isn’t something you say to counter an absurd argument. It is a logical argument where you point out that your own argument has to be the case or you reach a contradiction >

My argument is that not all people can ever all be old. If that isn’t true, we end up in your absurd situation. reductio ad absurdum >

you are still using RAA incorrectly, you have the implications mixed up. >

Well, how ‘bout we admit your premise (all old people) is absurd and entirely unhelpful in advancing any argument. >

no. I'm not even the person you originally started to object to, but their argument is clear.
The premise is "in an aging population, there will be demand for goods and services that outstrip our ability to supply it, which will result in inflation", with the (perhaps implicit) conclusion that "world population decline is a major problem."
They have used an extreme example for illustrative purposes in order to argue why the (far milder) premise holds, but that extreme example is not their actual premise.
If you want to refute their premise you need to engage with it as stated, explain why having only, say, 20-30% of the population (vs. current 50%)  in the working age bracket (25-65) would not lead to demand for goods/services outpacing supply and leading to inflation. >


Population really is the driver of power and economies. 

Say you want to open a business. Do you want to open it in a market with 300,000 customers or 300,000,000 customers? 
As a country, you want to have the largest population possible. If you lose too much population you lose your economic power. 
At a global scale, yes, a lot of innovation is driven by an educated populace, but it also stems from the unbelievably gigantic global market that creates demand for your products. 
Smartphones would not be as good as they are if it wouldn’t be a market of literally billions of customers. not to mention all the niche markets that would simply not be worth any investment into if there wasn’t enough of an international market for it. (the internet has enabled many of those markets in the first place by aggregating globally spread out customers into one neat virtual place.)

Age structure is hugely important. 

The last thing you want is a large amount of elders with only few people to run the economy. Unless you want 80 year olds to be working office jobs, You do not want 2 retired people for every working person. 
First, while people live longer, I would not consider a 70 year old today much more better capable of work than a 70 year old 50 years ago. It’s just that there’s a lot more of them now surviving until that age. 
Also while yes, people should be saving, most people don’t save as cash or investments. They choose to pay into pensions a set amount of money during their lifes and then get paid back later. That money isn’t saved by those institutions. It’s immediately payed out to the current retired, and when you retire, the youngsters’ money will come to you. If the ratio is too extreme, the working generation will have to burden the pensions. 
Gradual decline isn’t as bad, but for many developed countries, the decline is concerningly rapid. >

You don't understand the problem posed by an aging, shrinking population. 
Lets start with these three, because they're the same problem.

People are living longer healthier lives and are (or should be) saving to finance their retirement.
Ah! The poorly designed entitlement programs that just assumed indefinite population growth (see ponzi scheme). 
Deflation caused by an aging population.

LIFE ITSELF is a Ponzi scheme. We've always depended on younger adults to both take care of children, and take care of their elders, because they can't really take care of themselves. These 'entitlements' are simply how we do it these days, instead of shoving four generations into a single household and taking care of them that way. Which, if we still did, would have the same exact problem. More elderly, fewer children. Lots of folks just not having kids. The strain of taking care of the elderly will only get worse and worse as there's more and more of them, relative to the young. 
So unless you've got a solution to the 'retirees consume resource but don't produce resources' problem, you're going to need a healthy workforce to actually support them. It doesn't matter how much money they have if very little is being produced, transported, or maintained, because that money can't buy what doesn't exist. 
And remember, money is just a store of value, not something of actual value itself. You can't eat a fist full of dollars because it's not food. It won't heat your home because it's not gas or electricity. You can't call someone with it, because it's not a phone. You can't browse the internet with it because it's not a computer or internet connection. It's just some paper, if not just a number on a server somewhere. All it is is a bit of a social lubricant to make trade much simpler. This is why we can just print more of it (which is fine, within limits). Think of money as oil in an engine. The engine will seize up without it, but if your engine blows itself up, adding more oil to it won't make help any, just make the fire worse. 
The aging population problem really boils down to this. The elderly don't maintain infrastructure. The elderly don't pick crops in the field. The elderly don't operate power plants. The elderly don't manufacture. The elderly don't transport goods across the world. The more elderly you have, the larger percentage of your population you're dumping into the very basic maintanence of civilization. When this problem gets bad enough, everywhere begins looking like Flint, Michigan: You'll have water systems that needs maybe three or four times the maintenance to keep operating than you can actually throw at it. And this is across all sectors of civilization. 
At the end of the day, you can stuff money under your mattress. You can get into canning and/or jarring food and store a lifetimes supply of food in your basement. But you can't store a lifetime's worth of medical care, or internet access, or electricity. And we literally don't have enough water for everyone to remove a lifetime's supply from the water cycle. We NEED the infrastructure we have. Automation will only take us so far. It can make individual workers more productive in certain tasks, but we're pretty damn far away from the sort of post-scarcity fully automatic luxury gay space communism that it would take to actually run this hypothetical society. 

A decline in military strength.
Oh God. I'm not even going to touch this one.

You should. It's extremely important. You know why Russia went to war with Ukraine? Because Russian demographics are fucked. They will never be stronger. It's now or never. And now China is in the same exact boat. Modernizing will let them keep getting more powerful for several years, but they're going to peak. And when they do, they're going to start a war. They'll have no choice, unless they give up their ambitions. Something I REALLY don't expect the CCP to do. And you're going to see this happening with more and more countries, as they get more and more desperate and feel like their back is against the wall. Every regional conflict will flare up as national leaders realize that they can try now and maybe win, or not try now and definitely lose. 

Innovation comes from a well educated population. Not from a large population. 

Education helps, a lot, but it's also a numbers game. The more people you have, the more resources you have (human and otherwise) to throw at problems. It doesn't matter how educated you are, you aren't about to innovate a fusion powerplant in your basement with a box of scraps. >

Life itself isn’t a Ponzi Scheme. A Ponzi scheme is a term that has to stay more specified or there’s no damn point to using it. The critical idea of a Ponzi Scheme is that new investors are brought in to pay off old investors and that no products actually change hands, and no services are done. This qualifies social security but disqualifies life itself, as services and goods exchange hands.
For what it’s worth I disagree with OP on basically everything else, but he’s absolutely right to call out these poorly structured government welfare programs that were designed to fail. >


Unfortunately, because elders don’t have enough money to pay for adequate care, they will never get those caregivers. Workers will stay in better paying industries. We are looking at a potential for a crisis of elders dying of neglect.

The really sad thing is that it will be of their own doing. This is what happens when Boomers hoard wealth, vote for politicians that influence shit policies, help securitize healthcare, help undermine labor power and force people into other sectors of the economy to make a living. 
My friend works as a hospital administrator in a rural part of the state and they will not be able to care for the aging population. They can't find enough doctors and nurses. Not enough people are pursuing an education to become doctors and nurses are fleeing the field from burnout, being underpaid and COVID. 
Until the US makes major changes to benefit workers, strengthen labor rights, make education cheaper and more affordable for those scared away by sticker shock and the financial burden of schooling, our healthcare system will be a broken mess that can't support an aging population. A massive die-off of older, uncared for seniors will likely be inevitable. >

I especially worry for the growing number of childless people who will have no family to fall back on when shit hits the fan on elder care. 
Healthcare already employs such a large percentage of our population. Even if working conditions improve, I just don’t believe we have the capacity to allocate sufficient numbers of workers to care for a population with the amount of healthcare demands we have and expect to have in the future. >

And this is the main problem of population decline OP is not seeing. There are healthy 80/90 year olds who are self sufficient. But there is a lot who need care. And there simply won't be enough young people to do this, and no free market wishful thinking will change that.
So either we force people to go into elderly care while neglecting other areas of the economy, or let old people suffer and die. >

Requiring "a major problem" is potentially true Scottish territory here.
In the spirit of cmv, the good, please outline (as an edit maybe) what level of "problem" is sufficient to CYV.
You've spoken of other problems that you believe are more important.   That's a differentiation I can support.  But you haven't specified what other problems are more important. 
Eg "I don't think population decline is a bigger problem compared to the current projected pineapples on pizza issue" >

Right, so, what do you mean by not a problem?
Like, not a problem as in: things can run just fine as is with the elderly population growing larger than the younger generation?
Or not a problem as in: things cannot run fine because capitalism depends on exponential growth but if this is what it takes for us to get away from a broken system, then so be it. 
Because that's two wildly different statements. >

Not a major problem as we should be spending our bandwidth on other more significant and imminent problems.
Also, those who tend to think underpopulation is a problem brush off concerns over overpopulation, which I personally think is a massive problem that has caused countless other problems. >

You seem to be brushing off just how many of our systems and institutions rely on population growth. It’s not “overpopulation” or “under population” in absolute numbers that’s the issue here, it’s the direction things move in. A steady decline in population will lead to many of our institutions to break down, you can argue that’s due to their own bad design but that doesn’t change the reality of the situation. >

Can you give me some examples of institutions you think will break down? I've obviously pointed out the social programs, which I agree are problems are should be rectify. I just disagree with the notion that we need to someone reverse the population decline in order to find solutions. >

Social Security only works as a retirement income supplement because there are more people paying into it than drawing from it. >

Yes, I am aware of how ponzi schemes work. >

Okay so if that's what you want to call the current system then you are admitting that it relies on growth to stay functional, so option B in the commenters original question?
Population decline causes an en masse breakdown of existing systems and you're saying that's "fine" because the systems sucked anyway? >

That's a bit of a strawman of my perspective. There's obviously a problem with entitlement programs so we need to fix them so in the future they're not contingent on whether there's population growth or decline. And economy is self correcting for malinvestment if we stop doing things to prop up that malinvestment. >

There's obviously a problem if there is underpopulation.
You keep ignoring that the condition of underpopulation is sufficient, ceteris paribus, to create obvious societal problems, because you don't like that the institutions are designed in a way that allows it to be a problem.
But they are designed that way, so it is a problem.
It's not unsolvable. I want to do entitlement reform. But the fact that entitlement reform is necessary and that there's no political will to do it is a problem, and it's essentially a problem because of a lack of population growth, only. >

Problem seems to be a very subjective word, you can call something a problem from a point of view that really isn't necessarily a problem. The system we have has a flawed design that is what happens. The population will fluctuate and change, we shouldn't rely on the assumption that it will grow and it just can't grow indefinitely, making the change sooner than later is much better than just kicking the bucket down the road until we come into a wall... >


People are living longer healthier lives and are (or should be) saving to finance their retirement. Overall they should be getting less and less dependent on their children taking care of them and broader society.

I think this is a fundamental misunderstanding of what savings are. Ideally, if food and other resources never spoil, you'd want to save those up while you work, to be available to sustain you through your retirement. But they do spoil, so that's not feasible.
By saving money instead, you're giving away the product of your labour with an IOU in return. That IOU is only valuable to your retirement insofar as someone is around who has excess food/resources, and wants to trade it for your money. You don't depend on your own children, but you depend on broader society. >

A decline in military strength being no big deal is a very privileged and naive position to take.
I was living in Ukraine between 2020 and 2022. Left in January right before the war.
The economic catastrophe in Ukraine due to the war. Is absolutely heartbreaking. It gets overshadowed by the far more horrific war. Both things would be have been avoided if Ukraine had a stronger military. 
I really wouldn't discount the immense advantages a strong military provides for a population. It is the core of your standards of living. If China or Russia felt like they could win invading USA or Europe.... they absolutely would. But they know they'd get their teeth kicked in. >

It's also very naive to equate military size with military strength, particularly in the modern world.
Here's a ranking I found that doesn't show a whole lot of correlation between personnel size and strength of the military.
And speaking of war in general, most often war historically has been due to resource constraints and overpopulation. In a lower populated world, there would be less war. >


In a lower populated world, there would be less war. 

Where do you get this claim from? Do you have evidence to back it up? 
If you consider Earth's history, we have more people than ever before and less war than ever before. If you looked at a line graph showing global population and global conflict, population has been going up from day one, and conflict has been dropping. 
You would not know it from the headlines, but today we're living through one of the most peaceful times in human history. >

Seeing as the two most deadliest war in human history happened in the past century I think my claim holds. We're in a period of peace built on mutual mass destruction. >

This is obviously not a strong argument given that the worlds population has quadrupled since the end of WWII. >

That sounds like a very strong argument for not being too concerned about population decline. Thanks! >

Your responses reek of sophomoric dismissal of people that haven’t had the same privileges as you. Ask most of the developing world in Asia and Africa whether they want to return to the economic and global security circumstances of the mid-20th century. >

I don't follow your logic. What does mid 20th century conditions in Africa and Asia have to do with quadrupling the world's population since WW2?
On a side note, Africa is set to be the place where the world's population is expected to grow even more in the next half century. >

Unprecedented global security since the end of WWII, mostly driven by the US’ efforts to create economic alliances during the Cold War has allowed previously destitute countries to build out economies to serve global markets. It’s not a coincidence that global population and economic growth have paralleled each other at historically unmatched rates over the last 70 years. Global consumer decline with an aging population in the developed world fundamentally threatens this.
As for your side note, you are right and it’s a reason that conditions in Africa will likely continue to significantly improve. Population growth in Africa is a reason for them to be optimistic, as long as there continues to be globalized economies for them to serve.
Edit: I think OP’s refusal to respond to this despite commenting elsewhere demonstrates that they aren’t open to changing their mind. >


Edit: I think OP’s refusal to respond to this despite commenting elsewhere demonstrates that they aren’t open to changing their mind.

Exactly, OP seems very dismissive and muster up a rebuttal without being willing to follow through on the argument. It's the equivalent of doing argumental an drive-by.
I appreciated your comment though. I feel like a lot of Americans overlook the role that the U.S. has had in economic development in the rest of the world through their role as a security guarantor >

Gradual? Sure.
Severe population decline?
Supply chain logistics. Less workers means less capability to move supplies around the country.
Hopefully we have good automation on that front at that point. >

Your argument about end of life care is not sufficiently addressed. End of life care is going to be a huge problem if there isn't the trained medical workforce to sufficiently provide care. It will impact everyone because it will be a barrier to care for all ages. It keeps no professional caregivers out of the workforce as well increasing the need for government assistance for multiple generations. Elder care doesn't just affect the elderly. Remember that if you ever find yourself in an ER waiting for a hospital bed to open up. >

Don't the healthcare industry organizations forecast these workforce needs and make adjustments to salaries and program acceptance rates accordingly? I mean in theory that's what they're suppose to be doing year in and year out. >

If there are more nurses then there are less workers in other areas. Your solution seems to be “well we’ll just invent some really awesome robots!!” Which doesn’t seem realistic for things like personal care which need to be provided by humans.
We can’t have nursing robots. >


This point is simply not true.

I was speaking globally. Not everything has to be U.S. centric. And as Steven Pinker pointed out with tons of data in his book Enlightenment Now, we are living in arguably the best time humans have ever lived.

They is a strong political movement to cut medicaid, medicare, and social security

Other western countries are going through this as well, simply because these programs were designed based on the notion that the population will increase indefinitely. The general term is called austerity. Eventually the ponzi scheme collapses on itself. Between make adjustments sooner rather than later to minimize to ultimate fallout.

American military dominance is a big part of how we maintain economic hegemony around the world. The military is already struggling to recruit and this crisis will get worse.

I already commented on someone else's comment on this. It's a bit naive o assume military strength is a 1:1 relationship with the number of active military personnel.
And in any case the underpopulation "crisis" is going to hit China and Russia far harder than anyone else.

They're not. Maybe in an ideal world they should be. But they're not. 2008 should have told you that. Unfortunately economists like Hayek have a idealized view of capitalism and they don't really deal with the reality. I often hear the argument that the state should just not interfere, let the markets decide, let the banks fail, etc. Well, the reality is, the state does intervene, the banks and corporations do get bailouts and subsidies, and so on. That is the reality. And the state will do everything it can to stave recession when convenient. As we saw under Trump, the fed provide massive QE to prop up a bull market for years. 

Hayek's economic views still hold. If anything these "realities" you point to only serve to bolster the malinvestment case.

Global population decline can lead to a recession because where will the large cheap labor pool necessary for our commodity production come from? Things are made by people.

It really depends on what things you're talking about. Automation, digitalization, etc. take away the need for this large cheap labor pool you think must exist for us to live by the standards of today. That's kind of an antiquated view on where value and productivity comes from. >

The Jason Hickel op-ed in the Guardian says, "So what happens if we measure global poverty at the low end of this more realistic spectrum – $7.40 per day, to be extra conservative? Well, we see that the number of people living under this line has increased dramatically since measurements began in 1981, reaching some 4.2 billion people today. Suddenly the happy Davos narrative melts away."
Do you happen to know where that data is presented?  I'm interested to change my view if global poverty (as distinct from global extreme poverty) really is increasing. >

I’m not sure where to find his source tbh. Either way I think the number of people living below an arbitrary poverty line is sort of a red herring.
When people like Pinker or Gates say things are getting better and better, they are using that as a defense of the status quo. It is an argument that says “the system works.” But the fact that even one child is forced to work in a cobalt mine so we can have iPhones is a failure of the system. The fact that 18 million people in the US (the world hegemonic power, the richest country on earth) are living in “extreme poverty” (and 40 million more living in just poverty) according to the UN shows the system is failing.
And we know the system is not the reason we have what we have. Child labor had to be ended through violent struggle. The end of slavery took a massive civil war. The right to vote had to be won. The 40 hr work week had to be won. The history of liberalism is constantly fighting to have basic rights against the force of capitalism.
This kind of argument also ignores the more specific problems of global capitalism. For example how the lack of vaccination (due to Moderna and Pfizer hoarding the mRNA patent) led to countless deaths globally.
Or consider how the IMF enforces debt peonage on all “developing” nations which are not developing but stuck in slavery to the West in order to perpetually pay off their debt in dollars or pounds or Euros. The West is actively keeping countries down. We can see what the US and IMF did to cripple Haiti’s  economy as an example. Things are not getting better for these countries.
And every time a natural disaster or something akin to it happens, many countries slip further down. Cuba has struggled under the American blockade since their trading bloc with the USSR died. Iran has struggled economically under US sanctions. Madeline Albright famously gloated on TV about paying the price of half a million Iraqis to, idk, punish Saddam through sanctions. We don’t even have to go into the wars in Iraq and Libya and Syria and Yemen which have left these places in ruins. 
It is also a way for Pinker to basically wave away real problems. Does it matter if our wages are up by whatever percent if we are now living in slums? 
That’s another thing: these statistics are often meaningless. There is a common phenomenon happening across the third world where rural farmers are being pushed out of their land through privatization and foreign investment and forced into slums in the cities where they earn meager wages. This can show up as employment going up, wages going up, urbanization (mistaken for industrialization) going up, and all that. In reality it is a huge problem.
And as Hickel mentioned, the system looks good because China and its 1.4 billion people have propped it up. China played a huge role in saving the world economy in 2008. And it has brought a billion people out of poverty not by following the liberal consensus but rather going directly against it under the Communist Party. >


My view is well those are just very poorly designed programs. You can either rectify it or you can try to keep on kicking the can down the road.

Great, so what is your proposed alternative? You mention people "are (or should be) saving for retirement" - but 40% of seniors live exclusively on social security. I assume you do not want to leave them on the streets for not investing better.
And what are we supposed to invest in, our 401ks? Well those won't be worth much in a deflationary economy, where young people don't have the income to consume because a lot more productivity is needed to take care of the elderly.
I hear you, social security is a systemically flawed system... but so is democracy. It's great to criticize it, but I think we need a superior alternative before we just go "screw it", no?
Also, is it a ponzi scheme? 🤔 I think of it as "our social obligation to the elderly" (esp. b/c in our culture we are not expected to personally take of our elderly family members). I would gladly pay more taxes to fund it better, which seems like the more pressing issue, but that's me. >


A loss of culture and the diminishment of trust among citizens.
Is this really the number 2 reason? Cultures are constantly evolving and I think that's amazing. This is definitely the grumpy old conservative argument with not so subtle racist views.

Not really sure why you consider this a grumpy old conservative/ racist view.  
Population decline often results in displacement, which disrupts communities and causes loss of cultural identity, which causes all kinds of problems including a decline in mental health. >


People are living longer healthier lives and are (or should be) saving to finance their retirement. Overall they should be getting less and less dependent on their children taking care of them and broader society. Perhaps there might be a problem if there's a dramatic generational decline but gradual population declines don't seem that burdensome.

Western society is currently trapped in a misguided assumption that money buys happiness. The average Westerner spends all of their income every year.
Even those who set money aside and invest are going to lose their investment if the economy retracts from fewer customers/producers.

Is this really the number 2 reason? Cultures are constantly evolving and I think that's amazing. This is definitely the grumpy old conservative argument with not so subtle racist views.

Only someone with no knowledge of history can say this. Atrocities like National Socialist Nazism, Stalin and Maoist Social Communism, etc; are social ideologies that came out of a progressive agenda that resulted in genocidal catastrophes that set back those nations for generations.

Ah! The poorly designed entitlement programs that just assumed indefinite population growth (see ponzi scheme)... My view is well those are just very poorly designed programs. You can either rectify it or you can try to keep on kicking the can down the road. Canada has that flexibility due to low population density and lots of resources. Most countries unfortunately do not. See French protests as an example.

This is a very naive answer. You're basically saying the solution is, 'just fix it,' which isn't a solution to the problem.

A decline in military strength.  I'm not even going to touch this one.

This isalso a naive response. Of course it'd be great not to need a strong military (or one at all) but that's not the world we live in. Many countries around the world would not have their freedom without the US's military might (South Korea, Taiwan, most of SE Asia, 20th century Europe (twice), Iraq, Kuwait, and many many more).

Innovation comes from a well educated population. Not from a large population. There are a ton of innovations going on in small population countries. Nobel prizes per capita would be one metric to look at. 

The US currently has more Nobels than I think all other countries combined. This without being even in the top 25 in level of education. It'd be a hard sell to say this isn't because the US is a top 5 nation in population.

First, I don't buy a population decline would be permanent recession, particularly on a GDP per capita basis, which is the true metric we should be focused on. Relying on continued population growth as the main component of your company's growth just means you have a bad company. Recessions are a way to clean out malinvestment in the economy.

The US's massive economy didn't exist without reaching a large population size, especially the baby boomer generation.
Companies don't entirely rely on population growth but it's hard to grow without more customers and workers.

This goes back to my malinvestment argument. The only reason economists fear deflation is because falling consumer prices means less revenue for companies selling those products. But my argument is the good companies will and the bad companies will be shown for what they are. At some point deflationary pressures would abate.

This is not how any depression or recession has played out in reality. Recessions cause all economic activity to contract, not just purchases from "bad companies." Saying that "deflationary pressures would abate at some point" is a cop out answer that means nothing. >

Nazism was definitely not a progressive agenda.  It was a violently reactionary swing towards traditional values. >

The Nazis believed in creating a genetic-eugenics utopia by classifying people based on physical-ethnical features, and systematically eliminating the undesirables. None of that is traditional values. >

It was absolutely based on traditional values.  Using bunk science to support your "let's make this country super white like it used to be" conservative politics are are still conservative politics. >

What part of Nazism was traditional?
Nazism was a socialist party that exponentially expanded the government to socially engineer society into a hierarchy based on eugenics. That's one of the most progressive agendas there has ever been.
This is why I compare it to communism. Another anti-religious, social-economic societal engineering, ultra-leftist revolution that had never existed before.
To have an argument you're going to have to offer more than "conservative politics are are still conservative politics." I'm only going to argue with someone who offers some sort of logical evidence to support their claim. >


What part of Nazism was traditional?

The nationalism part.  The "let's make our country super white again and get rid of the religious/ethnic minorities" part.  The homophobia.  The veneration of the military.  The "our country first attitude."
Basically everything but the fact that the word "socialists" was part of the party name.  I don't know why conservatives love focusing on this one fact and ignoring all of their actual policies.  And the fact that "nationalist" was also part of the party name. >

Inverted population pyramids are unstable. % of robots will far exceed humans in the future to stabilize this. People might oppose that strongly, potentially increasing social fragmentation. >


A rise in the dependency ratio which would increase the economic pressure on the workforce.

People are living longer healthier lives and are (or should be) saving to finance their retirement. Overall they should be getting less and less dependent on their children taking care of them and broader society. Perhaps there might be a problem if there's a dramatic generational decline but gradual population declines don't seem that burdensome.


Im gonna need some clarification on this. Are you mostly referring to the financial capacity of the elderly to take care of themselves? Because I think a major cause for concern isn't necessarily just the need for children to take care of the elderly but rather a larger-scale issue where there aren't enough/as many younger people to fill in the positions left vacant by the now retired, an issue that I'm not so sure would be solved simply by the elders being able to pay for their own care. >

Older people are financially more well off which means they tend to lead more healthier lifestyles and can be independent for significantly longer. There's also a strong economic inventive to fine solutions in elderly care.
And it's not like there's a massive cliff we're staring at. It's more like a gradual population decline. Perhaps China, due to its government policies is in for more pain around this issue but in general I don't think it's such a concern that we need to pit every last bit of effort into trying to reverse the population decline. >

Independent living doesn’t mean they aren’t consuming large amount of healthcare resources to maintain themselves. My 80 year old neighbor is wealthy and incredibly active. Grows and preserves all his vegetables. He is also hospitalized for a few nights at least once a year for some or another life-threatening event. That’s on top of frequent doctor visits and meds. >

Right! People being independent for longer doesn’t solve the problem of how much care they need once they can’t be independent anymore because they have physically and/or cognitively declined to the point that they can’t live independently and need people to assist them.
And even if we assume - as OP does - that everyone has the financial resources to pay for their own end-of-life care (and with modern medicine that end-of-life can take a long time!!)… you still need to be paying someone to provide that care. And there need to be enough someones around to provide that care. >

The UN panel on climate change itself mentioned that demographic change, I.E. population and birth rate decline, is a bigger problem the next 100 years than climate change. >

Hey I'm going to suggest something I've not seen anyone else say yet.
A shrinking, aging population is extremely bad for the environment
Not a lot of people know this but there's something called the Jevons Paradox which is essentially about how our consuming wants and needs scale disproportionally to the amount of resources available of us. The implication for a shrinking population is essentially that for every 10% fewer humans we'll use 25% more energy. This feels counter-intuitive but we actually see that in day-to-day life. When a road experiences traffic congestion and the road gets expanded the traffic congestion actually increases instead of decreasing because the usage goes up faster for every extra lane added compared to its throughput.
When humanity switched from candescent lightbulbs to LED (which use only 10% the amount of energy) humanity decided to use more than 10x the amount of lighting for the same things so we actually use more energy on lighting now compared to before.
When there are fewer people the demand for these goods will go down, if demand for energy drops 10% then the demand for energy rises 25%. It's more than likely that a drop in population will result in rising environmental damage and resource usage with this paradox in effect.
Another negative effect to the environment is that fewer working age people means fewer brains to tackle the environmental problems humanity faces and thus a slower adoption of renewable technology which indirectly means a worse more polluted planet compared to a timeline where humanity kept growing in numbers. >

Peter Zeihan out lines it well. >

I disagree about quite a few things he says, but I think he has a great analysis on why population decline causes many issues. I think the next century of the US watching it play from afar will inform our thinking going forward. Pretty much all of Western Europe will be a battleground of economic ideas to accommodate aging population and demographic crises. >

And the number one way to solve it most of them is to bring in more immigrants to do the jobs locals choose not to do anymore (cleaning, nurses, care of elders, so on).  This creates a gap between the locals and low income immigrants. And leaves the countries of origin missing a big chunk of working age people, the educated ones especially. >

And some countries won't allow immigration because of how homogenized their society is (think Japan and South Korea). Others have very restrictive immigration policies. It'll be interesting to see how those fare without a large enough native population to sustain themselves while also not bringing in young and usually skilled immigrants to make up the difference. >

The problem is that populations are declining in the most productive parts of the world. Parts of the world where people are wealthy, educated, productive, contributing to science, etc will see population declines. The west and the rich parts of asia will see massive population declines. 
Meanwhile the parts of the world that will see population increases are dysfunctional. Afghanistan and sub saharan africa are going to see population go up this century. Those parts of the world are not contributing to solving the world's problems. If anything they create problems that the rest of the world has to get involved in to try to help solve. Political problems, health issues, poverty issues, etc that the rest of the world has to try to solve. 
Fertility is negatively correlated with education and wealth. As a result the most educated and wealthiest parts ofthe world are seeing population declines while the least educated and wealthy parts of the world will see a population increase. 
hopefully as Africa or places like Afghanistan see their wealth and education go up, their fertility will drop. But as it stands the most dysfunctional parts of the world are seeing their populations increase while the most functional parts of the world are seeing population declines. >


People are living longer healthier lives and are (or should be) saving to finance their retirement. Overall they should be getting less and less dependent on their children taking care of them and broader society. Perhaps there might be a problem if there's a dramatic generational decline but gradual population declines don't seem that burdensome.

When the population declines the cost of care increases, it basic supply and demand, more and more elderly people need care, but there will be less people to supply the care.

Is this really the number 2 reason? Cultures are constantly evolving and I think that's amazing. This is definitely the grumpy old conservative argument with not so subtle racist views.

Yes cultures evolve but it's not always amazing, it can cause division amongst citizens and lead to social and political uprisings, civil wars etc, it's not racist to point this out many countries and empires throughout history from Europe to Africa to Asia have had devastating consequences because of this.

Ah! The poorly designed entitlement programs that just assumed indefinite population growth (see ponzi scheme)

But that is the system we have now, whether you like it or not that is how much of the world works, it's all well and good criticising it but unless people can come up with a more sustainable solution it will continue to be a problem.

A decline in military strength.
Oh God. I'm not even going to touch this one.

Like it or not country's need militaries to secure their safety, a decline in population not only harms the military due to less people in the military but it also causes less productivity, less innovation, worse technology.

Innovation comes from a well educated population. Not from a large population. There are a ton of innovations going on in small population countries. Nobel prizes per capita would be one metric to look at.

Let's say there are 2 countries.
1 country has 100 citizens and 1 Nobel prize winner.
The other has 1000 citizens and 5 Nobel prize winners.
The smaller country has more Nobel prizes per capita.
The small country had the Nobel prize winner cure cancer.
The larger country had the winners...
Cure dementia.
Discover a new clean source of energy.
Develop drought resistant crops.
(Random innovation)
(Random innovation)
Which country do you think benefits more ? >

From what I can tell from reading these comments, OP is saying that population decline by *itself* is not a problem. The fact that we have economies and societies that do not function well on a declining population is not the fault of the decline but the fault of those economies and societies.   
I mean...yeah, I don't think many can argue that. But that seems like a no brainer to me? society A has an economy that thrives on a larger eldery population. Society B has an economy that thrives on a larger young population. Society A does much better during a population decline than society B.   
In that scenario, you do not say 'ahha! Population decline is the problem! I must increase population' You say... No kidding, Society B should probably learn to adapt their system to this new reality.   
And I don't think you can argue about the ability to adapt. We're capable of it, certainly. But things won't remain as is. But again, I don't think anyone is arguing this? I could be wrong. >

A rise in the dependency ratio which would increase the economic pressure on the workforce.
You mention here that older folks should have saved for retirement. People planning for retirement save money, they don't save any magical completed products to be redeemed later. If there aren't enough workers to supply those goods, the money they have doesn't matter. This is because the assumption for the past ~80 years has been that there will not be an involuntary supply side shrinkage. Money does not magically will workers or goods into existence; at that point it's just paper. 
To take it to its extreme, imagine a country where 70% of the population has retired. It doesn't matter how much money they have, they will be competing for an amount of goods far less than necessary to sustain them. 
This is a matter of balancing numbers, so sure, some advancements in worker productivity/automation might allow for such a small portion of the population to provide for the rest. That isn't guaranteed. >

So essentially productivity gains through scale and automation would just need to keep up or exceed the decline in workforce relative to the elderly who need that care. That seems completely feasible, particularly if there's a strong profit motive (from these savings). >

Old people having more money (if you want to assume that people, en masse, all do what they should, which is an argument in and of itself) wouldn't change that a higher ratio of them in the overall population would require diversion of real capital and labor towards their care - them being to afford it financially is less the issue than society as a whole having to shift away from other endeavors by some degree in order to do so. This then cascades directly against your point about less strain on the system when talking about potential innovation - a lower proportion of available capital will be usable towards such ends in this scenario.
Also, no, economists fear deflation because it leads to spending on non-essentials drying up as people and businesses are incentivized to wait, especially for larger and/or longer-term expenditures. You could look at this as weeding out less profitable/more risky ventures since anything with an ROI less than the deflation rate would have no investor appeal, but then you just end up without enough overall activity to fill out the economy because the world just hasn't ever been full of safe high-profit-margin opportunities.
It seems like your line of reasoning overall ultimately rests on the idea that because there could potentially be a way of responding which wouldn't be highly problematic, that would be the way things go, without accounting for the how of getting there. >

Well, I think the “elephant in the room” of discussing population decline isn’t the total number of people but who—which people—are still breeding. I’m not into Frenology or selective breeding; I don’t even like it in dogs. Thing is, eventually, the movie Idiocracy starts to feel more like a documentary.
I don’t think it’s worth quoting statistics here, because steep and/or steady population decline is almost never good, regardless of cause. Your example is not all that insightful, either, since we’re not at a socio-political place in the world where not have a lowest rung of society means anything but the next lowest will just be the lowest. >

Someone has to build things and provide service, if a large enough portion of the population isn’t in the work force, then you are going to have shortages of workers and goods causing inflation. That inflation is going to cause young people to not want to have children and the problem is going to snowball. >

An important distinction that I think needs clarification in your argument is scope.
Is  world underpopulatuon a problem for humanity as a whole? Maybe, but I tend to agree with you, probably not. It may lead to breakdown and substantial change of current systems, but it seems a thing we can adapt to.
Is national underpopulation a problem for individual nation states? Absolutely. It's difficult to make an argument that the power of a state isnt harbored in the capacity of its people (and natural resources). If you have more people, you have more human resource to do and accomplish things. If you have more people, there's better odds that you have remarkable individuals, engineers, doctors, leaders, that are capable of producing higher quality of lives for your people. If you have more people, your more likely to have the capacity to develop the military technologies that keep us secure, as well as having the bodies to man those arms.
If your looking for examples of this in practice, look into the rise of India, a country more barren than most in its natural wealth (and with a history of being ravaged and colonized) that has managed to develope into a growing economic power and producer, largely by holding one of (if not now) the world's largest population. 
Underpopulated nations are likely to fall behind in economic rank and lose buying power for the resources necessary to maintain the quality of life most 1st world nations enjoy. >

this is one of my favorite posts here, my boyfriend and I were literally just arguing about this. he came from a more emotional standpoint, asking me things like why culture/love/human experience degradation would ever be a good thing. and I was like I mean there are negative aspects but I really think it’s overall a good thing. we’re a parasite to the planet, and every good thing we’re given we abuse as a species. 
it’s funny that we’re the only animal that claims to have a moral compass, yet create the most disgusting and brutal circumstances on purpose. I think a declining birth rate, especially one that is, in part, due to women being granted rights and bodily autonomy, isn’t necessarily a bad thing… >

Why are we centering an economic discussion around points listed on Wikipedia? >

Because Wikipedia acts as an aggregation of perspectives and arguments on nearly every topic. And there's a community vetting process. But if there's a point you wanted to make that wasn't covered by the Wikipedia list, then I'm opening to hearing it. That's actually what I'm seeking. This is a CMV after all. >

It is if you like social welfare, that's paid for by the masses of middle age people. And pensions will be the last thing to go because older people vote the most consistently and pensions were the first social welfare program to exist in most western countries. This means that the young will lose support causing them to make less at middle age and then in turn rely on pensions even more. This will cause the decline and rollback of the entire welfare state, then once the welfare state is rolled back and the majority are incapable of feeding themselves religion and "charity" can step back in and allow old money to totally dominate culture and politics, allowing them to eventually rollback the expansion of the vote and we'll slide right back into the 18th century except this time the rich won't need the poor for war or for work in factories so all of our cards will be gone.
A lower than replacement rate for humanity might be the single worst thing happening for the long term effects, besides climate change. >

Won't someone think of the shareholders??? >

It's a problem with growth-based economies, which will lead to economic decline and hardship for everyone. In the long-term, the shift away from growth-based economies is inevitable. The problem isn't that populations will decline, the problem is that existing economic systems are based on there being enough young/working people to sustain old/rich people. 
In Japan people aren't dating, or getting married, or having children, because they have an overbearing work culture and a political system designed to benefit the older generation. This means the ratio of working people to non-working people is steadily decreasing to unsustainable levels.
TL;DR: Rich people are freaking out because they need lots of low-cost labor. Nationalists are freaking out because GDP is all that matters. Old people are freaking out because they need young people to take care of them. Young people are slaving away under a system designed to benefit everyone but them. >

If the world is still too “populated”  to house the unhoused and feed the hungry, a decrease in population is the least of our worries. >

If you believe in capitalism, then a population decline is devastating to an economy that is expected to grow each year. >

Honestly if I have kids they will likely live on a dying planet with no supports, why would I ever bring a kid into that? >

Underpopulation theory is fucking insane. 
"There's too many natural resources and not enough consumers!!!!"
That fucking crap.
People can do labor, even skilled labor, well into their seventies. 
Have you never seen two male nurses lift an obese 60 year old woman onto a gurney? That shits great. >

Assuming people are active and productive into their 70s means they’re probably healthy enough to live a long time after that. Increasing quality of healthcare means that people take longer to die and extends the period between “unable to work” and “dead”. 
If people can work until they are 70 they don’t die at 80. They might not die until they’re 100. 100 year old people need a lot of assistance and healthcare! >

Man, just scrolling through the first 100 comments I still haven't heard anyone really give a good response that we are facing a crisis due to declining numbers.  I was really hoping to see one. >

Me too. >

More short term problems would be that dependency ratio you were talking about. What happens if people don't have kids? There's no one to take care of them, and if they were to go to a nursing home, it would be understaffed. On top of that, older people rely on many healthcare professions as they get older and become ill. With a dwindling workforce to patient ratio, it would be difficult to meet that demand. Of course, the long term problem with a population decline would be extinction lol >

Sounds like a scenario ripe for innovation in the healthcare sector, no? Sometimes system constraints force us to do things a better way. I can rant all day about how healthcare is the least efficient industry we have but that's a topic for another day. >

I guess, but that could be taking up too much of our resources when it could've been put elsewhere >

How do you reverse the declining population, once it has reached what you consider an appropriate size? >

Self balancing. Standard of living will continue to increase, lowering the hours of the average work week. Property values will become more affordable due to more space availability and lower demand. People would be able to start families or have bigger families. >

Fertility rates have begun to decline in lots of places around the world.
Multiple generations in Japan and South Korea have been born with sub-replacement fertility, for example.
Has anywhere exhibited this “reversion to the mean”, where fertility rates sub 1.5-1.7 have returned to replacement or better? >

Japan and South Korea are also the worst if you're going to pick example countries to back up your perspective. Japan and South Korea also have some of the highest working hours for developed countries as well as cultural distinctions which probably also contribute to their fertility problems.
To be honest we're currently in uncharted territory in recent decades so unfortunately empirical data is all that great. All we can do is identify the causes of low fertility and use logic to understand how those factors would change over the long run as standard of living increases and population declines. >


All we can do is identify the causes of low fertility and use logic to understand how those factors would change over the long run as standard of living increases and population declines.

Education, irreligion, and wealth are all negatively correlated with fertility on a global scale.
I can appreciate that property values have a big impact, but they aren’t going up because population is high so much as due to urbanization and needing to live in or near a city for the best jobs. As the population pyramid tilts toward old homeowners over young renters, I think the political issues will get worse.
Relatively fewer young people also mean fewer young people to work jobs like construction or repairs and maintenance. >

In most Western countries, about 20% of the population works in the public sector. This is the stuff that makes a country work. That 20% by definition comes from the working population.
If the birthrate drops as quickly as it is at the moment, in a couple of decades the working population will be substantially smaller, but the total population will only be slightly smaller.
At this point, either we have to reduce the number of public sector workers, or increase the percentage of the working population that work in the public sector. Either of these will have significant impacts - we either have to cut back on public services due to fewer workers, which are generally pretty important for a functional economy, or the economy has to shrink faster than the rate of population decline since so many people work in the public sector which is paid for by higher taxation. Suddenly all those people who saved for retirement see their wealth plummet in value. >

China will not be a superpower single handedly because they will experience depopulation. Everything else could go right for them but because in the future they will have a lot of old people and very few young people, their entire economic system will focus on supporting those old people as opposed to building new things. The us in comparison will have comparatively decent demographics due to immigration which will allow them to at least try to maintain a large consumption sector. >


Difficulties in funding entitlement programs because there are fewer workers relative to retirees.

This is definitely one of the biggest problems with population decline. Thank you for acknowledging these systems are currently set up as ponzi schemes, because they are. When government does it though, I guess it's ok... 
The other big problem is companies will not be able to sustain their operations due to a lack of people. This might not sound like a bad thing at first but when you realize that it will necessitate consolidation of firms and therefore reduce possible competition that is guaranteed to be a bad thing for consumers. It will also lead to reduced innovation. You assume that somehow education solves for this but it doesn't. Education can help people reach their potential, but every person has a threshold for their potential and that threshold is not the same. Some are born smarter than others. That's just the way the genetic cookie crumbles. So, less people means less people of immense potential to have those absolute breakthrough ideas. >

Young people often bring change. They are the ones to revolt against an oppressing force. If there are less of them then change in the society won't happen fast enough. The people with power can simply keep the population under their control for a long time. >

You didn’t actually make a case here that underpopulation isn’t a problem for entitlement programs. You’ve framed it as a solvable problem, but since the problem isn’t being adequately addressed by really any nation, then it is still very much a problem.
Unless you’re arguing that since the problem is theoretically solvable, it doesn’t count as a problem regardless of actual action taken. >

Man, you try going through a labour shortage.  Sure theres jobs everywhere, but our hospital in my town is diy because we cant get any help. >

Long story short is that most of these were fine points.
The most pressing point seems to be that the larger the population the more art created, the more films and movies produced. The more music that is created, the more scientists we have to discover things, etc.
This point by itself really looks to outweigh all the arguments against it.
I’d just like to say that if you believe that the world is facing a natural resource shortage you’re probably just underestimating capitalism’s pros and cons. >

In the 70s, overpopulation was a huge concern & it was widely assumed we couldn’t produce enough food, let alone everything else, to support the increasing population.  As the population increased & food became more abundant, they realized human ingenuity is a resource in and of itself so that’s one possibility.
Another is that the system has become dependent upon growth.  To put things into perspective, at the worst of the US housing crisis post 2008, we only had a 6 month supply of housing.  So in the worst real estate crisis of my lifetime, construction could only stop for 6 months until we needed more housing. >

It’s a problem for the “economy”.  I can’t change your mind, because I think population decline is inevitable and necessary.  It’s something no one seems to want to talk about.  
Infertility is an increasing issue.  Gender equality is creeping along and may someday reach a true equilibrium (capitalism will shudder if/when that happens and more women opt to not raise children while sacrificing a lot of other things).  We have an economic model that has proven itself unstable for long enough.  We’re currently in a state of obvious overshoot.  In the era of cheap energy, we have been unable to decouple economic growth from energy use or resource extraction…and on the current trajectory we’re likely to reach limits on these things in the near future (barring the success of “technology” to provide…or colonization of another planet while we leave paradise behind).  Technology has historically only recirculated “efficiency” gains back into the system…so doesn’t seem to be capable of solving our energy woes (granted something unknown could change that).
Food resilience could easily tank in the next decade…contributing to the already massive annual body count of 10 million from food-related malnutrition/starvation.
Assuming geopolitical tension doesn’t tear us apart and cause nuclear Armageddon, we’ll likely start flooding coastal rice-growing regions (buh-bye #1 food staple, succeed in acidifying the ocean which will disrupt most of the food chain.  Mass climate migration will likely continue en masse.  Ba bam.
Unpopular discussion…because many people assume advocates of decline are racist or elitist…and have some sort of purification agenda.  And no one seems to have the balls to talk about how flawed our ideology of growth really is.  It’s an out of control machine that thrives on growing inequality and Ecologic abuse.
I’d say we’re fucked.  And many people are going to die.  
I’d rather be optimistic.  But we’re so divided in the parts of the world that need to execute change that we can’t even talk about this shit. >

I think it’s important for governing bodies and society to remember how challenging it can be to raise kids in a household that requires both parents to be earning. If you want women to have more children than obviously there should be an incentive to having and raising children. I’ve seen what kids are like and I know expensive they are. I’ve seen how useless and traditionalist husbands can be if they don’t just decide to leave. Without help in this economy there will be thousands of women unwilling to take on that burden. >

I think the worst part about population decline is a smaller percentage of people have to pay a bigger percent of the pie for all the retirements.  If you tell an old person they are not gonna get all their promised money because of population decline they might hurt you. thanks boomers I cant afford a house either. that money has to come from somewhere the young people are already paying for it >

Curious to me that the majority of the top posts are about financial concerns.
What of the resources?
If, like OP suggests, we have significantly less people, we could:
A) revert to a size of populous-structure better fitting Dunbar's Number, possibly alleviating social chaos and, more importantly,
B) Cease draining the world's resources at a wildly unsustainable rate.
... is capitalism really more important than peace and sustainability?
Isn't a secure future worth the cost of 'losing out' on the potential benefits of growth-oriented planning?
...kinda with OP on this one. >

None of your points address the issue at all. The crux of the issue is that you're going to have a bunch of old retired people when there's far less young people. Whose going to do all the jobs in society if most people are retired? You'll have to send the oldies back into the work force which will lead to massively less productivity and an eventual collapse of modern society. >

I’ll bring up something nobody else has. The world economy is a house of cards that requires ever expanding debt and money creation to not collapse. A declining population is inherently deflationary to physical assets, namely housing, food, and energy, and while this wouldn’t be a huge deal in a hard currency economy (ie one with a finite money supply), it creates a problem given how the economy is constructed.
An aging population means a major contraction of debt issuance, both because old people don’t borrow much, and because deflationary pressure would mean assets like real estate could be purchased with smaller loans.
Additionally, deflationary pressure means that there is more incentive to default. Why keep paying your loan when you’re underwater and it’s getting worse?
The combination of credit contraction and defaults will spiral the economy out of control to the point that all the TBTF banks can’t be propped up. >

Let's take this from the core problem. 
Humankind will die.
Given that (almost?) every civilized nation has below replacement birth rate, and assuming more countries will develop, people will simply die out.  
The number of people will peak, and unless there is a major change everywhere, people won't have each 2+ children, and population will continue to decrease with no end in sight. >

I feel you're fairly conveniently glancing over some of these problems.
People should be saving to finance their retirement anyway! A lot of people aren't doing that and a lot of people aren't in a position where they are even capable of doing that.
A loss of culture? Big deal, cultures changes! Well, it is a big deal if - as you point out - it leads to increased racism and societal problems.
There are a tone of innovations going on in small population countries! Yes, but these are not countries that used to be large population countries and became innovative when the population started decreasing. They're not adapting to the issues brought in by population decrease while they're being innovative.
Ah, but it's ok cause bad companies will be shown for what they are! That doesn't mean that it's not problematic. We can probably agree that cigarette companies are pretty bad companies, but if it was announced today that the whole industry will be put to stop by the end of the year, it would still be a pretty massive problem with dozens of millions of people getting unemployed out of nowhere. Would make it a lot harder for them to save for their pensions too, wouldn't it?
I suppose it all boils down to what one considers a "major problem" but what makes the world population decline a major problem for me is that it causes a lot of these problems that are pretty big on their own. But of course any problem can be dismissed if you focus on the positives and ignore the negatives. Global warming is fine because maybe finally the planet will be free from humans polluting it. Nuclear war is not too bad because the world is over populated anyway and we're such slaves to capitalism that hitting that reset button would probably do us good etc etc. >

How else am I going to get my social security check in 30+ years
You need to feed the socialist pyramid scheme or else I won’t get my money back! >

Take Japan for example. They are getting to the point where the population of retired elderly is increasing and the young working class is decreasing. 
Without a doubt, that's a big problem. I remember seeing reports where retired elderly commit petty crime, just so they can be imprisoned because they are either 1) causing financial strain on their family and/or 2) alone with no one to take care of them. In addition, the stress on the younger generation is now way high in compared to the older generation, the suicide rate is way up. 
Even in US, I remember seeing a news story saying the age of ppl having children is increasing because of financial strain on the young generation, and there are increasing population of younger generation deciding to just not have children at all because they can't afford to. 
When the human population was increasing, we have more younger ppl supporting older ppl in the society. That works out okay. But if you have more older ppl and less younger ppl, shit's gonna go bad. It'll just be a lot of elder ppl who needs ppl to take care of them, but there's less younger ppl its putting a crap tone of pressure on the younger ppl. 
From personal experience, both of my grandparents from my mom and dad's side have more than 4 children. So caring for my grandparents were "easy", because all of their children switch and help out. However, all of my cousins are single child because their parents just can't afford more than 1 child. Now, my generation, it's me taking care of my mom and dad, and what's worse, is it'll be very likely, that my future wife's parents needs care as well. It'll be like 1 couple (me and my future wife) taking care of 4 elder ppl....that's so much pressure. >

I would argue that #2 isn’t just a racist old people thing. Culture is real, and it is IS an issue when there are not younger people who are willing to carry on traditions. Like yes your culture is likely fine, but the world is globalizing and not all of that is a good thing. Languages fade. Burial customs fade. True and deep and lovely things about human culture are lost.
I lived for years in mayan country, and they are very traditional. They are not interested in being something else. They are the maya. (Of course, there are many tribes in mayan country, and I can only speak to the one I lived among. Others vary, I’m sure). They have traditional dress and language and customs. They largely shrug off government intervention and live their own way. 
The mayan culture is particular, but it isn’t THAT particular. People have traditions and linguistic things and ideas that are cultural, and they are a lovely piece of humanity. Losing them is just that— a loss. Would you call my 89-year-old neighbor a racist because she doesn’t want her kids to move to the US just to make money, and lose their traditions that have been passed down for thousands of years? I suspect you wouldn’t.
Decline in birth rate means fewer people to hold a whole thing afloat. I think you probably understand this, but you have a different mindset than my grandma neighbor. That’s ok, but i suggest you look into what culture really entails before dismissing #2 on your list here. >

Our global economic model is based on hyper-coordination in a highly interconnected world.
If we experienced, say, a 30% flat reduction in global population evenly distributed around the world, we would be unable to produce, ship, and process goods and energy. It would create a global economic collapse that would cascade all the way down.
Now, I'm not saying it would kill off the species, but to an economist like your professor, a total collapse of the modern globalized economic model is basically the end of the world.
Gotta think about it from their perspective. >

It's all about the rise in the dependency ratio and the problem is that while it is true that people are living longer and healthier lives their length of life is increasing by more than their length of healthy life. People are living 20-30 years longer than they used to, but they're only able to work for maybe 5 or 6 years longer than they used to be able to and so their dependency ratio is increasing even if they are self sufficient. It's not possible to support an extra thirty years of life with an extra five years of work, particularly because end of life care is getting more and more expensive. In particular: we've developed the technology to allow our bodies to live for longer than our brains can. That means more and more dementia patients, and dementia care is exceptionally expensive. >

Just think of everything people are doing in the world. The possibilities because we have so many hands and minds. Now think what can be done with 10% less people, 20%, 30%...we will simply be forced to do less things, think about less things, etc. >

I think that's a bit of a fallacy... the occurrence of revolutionary innovation is directly proportional to the population. If that were the case Nobel Prizes would evenly distributed across countries on a per capita basis. And the advancements in scientific fields would be quadruple today than it would have been in the early 20th century.
Then there's how you focus your innovative capacity. In an overpopulated world your focus would be on averting the issues cause by overpopulation. But if you had a more sustainable population then that innovative capacity can be focused elsewhere. >

I agree with this entirely.  I haven’t seen someone touch on how our overpopulation has been pushing our natural resources to the brink for decades. And the issues that come with population decline seem to reflect issues with late stage capitalism. Things will change for sure but they always change.  The old will eventually die off and the young can finally try to take care of the land as we should have long ago.  I just don’t buy any of these arguments as something that won’t eventually benefit us to go ahead and deal with in the long run. >

The main problem is that the people who are having kids are third worlders who are not white. I am white, so therefore this is a problem for me and my genes. If you are a member of one of these peoples who are gaining in number and territory, then it is obviously not a problem for you.

Is this really the number 2 reason? Cultures are constantly evolving and I think that's amazing. This is definitely the grumpy old conservative argument with not so subtle racist views.

You say that because you have never experienced conflict and therefore you think the current lull will last forever. Multiculturalism is only workable because white people has imbibed liberal humanism. The current ideological paradigm will not last forever, especially since its main supporters are not reproducing. Human nature has not changed and will reassert itself.

Innovation comes from a well educated population. Not from a large population. There are a ton of innovations going on in small population countries. Nobel prizes per capita would be one metric to look at. And with a smaller population there would be less strains on the system as a whole so less need to focus innovative capacity to alleviating those strains and more focus on revolutionary innovations.

Obviously it is better for technological growth to have a large educated population than a small educated population. But education is not sufficient to produce highly intelligent population unless there is a genetic basis, which there won't be because the high IQ people are not replacing themselves.
Dark age ahead. >

Well underpopulation won't be a problem, pensions will be younger people will be taxed more and more  until they lost any motivation to work >

I think you need to separate the population being smaller with population becoming smaller.
People haven't saved for retirement. A lot of old people that can't work anymore depend on the money the government pays them from the taxes they charge the working population. If that ratio gets too skewed, then you have a problem. The problem isn't exactly when the population starts to decrease. It could happen when it's not increasing as fast, or it could sustain some reductions with no problems, depending on the health of the economy and other factors.
There's a problem with the population being smaller which is we would be doing less science because often science is funded by taxes, so a percentage of the amount of money the population generates. For things like health care, it may mostly go hand in hand (less money, but also less people to care), for things like inventing MRIs then it's a problem, because inventing MRIs takes the same amount of money whether you need 1 or a million. >

Lots of text in this thread but the logic is very simple. Will it reach this point? Who knows but here’s the idea:

We require goods and services to live our modern lives. 
Those goods and services require people to make and do them.
A population that is weighted non-working (elderly) will have many people drawing resources and fewer making resources. 
Economic issues may follow - not enough goods and services, instability, lack of innovation or growth. 

Whether it’s making toilet paper or repairing AC units, it doesn’t really matter - there will be fewer people to do it, and a larger percentage of workers taking care of the elderly with medical or nursing care. 
The possible outcomes are numerous and no one knows for sure if this happens on a global scale. But we have many smaller examples, and there is a clear decline in productive capacity >

You mentioned saving for retirement. One thing to realize is that money savings doesn't actually increase the supply of available goods. The remaining workforce still has to supply the goods they will buy with that money, and the sustained demand for consumer goods and services, coupled with a reduced supply of labor, will drive (and, I believe, currently is driving) inflation. >

Some people argue a declining population will actually cause deflation. That was one of the points noted in the Wikipedia article on the topic.
But to your point specifically, I predict a combination of automation, elderly independence, innovation and outsourcing will avert such a supply shock. >

The "problem" is that capitalism requires exponential growth or it collapses. >

I've just became aware that the country I live in, Thailand, is experiencing significant decline in birth rates, so that there are only half as many people at young (<10) ages than are middle aged, per each year of individual age. This question and discussion is about what's likely to come of this. For the last half dozen years population level is stable, not declining, because life expectancy keeps increasing. In 20 more years they could easily be jammed up with a relatively large retired population and relatively small young population; there will be twice as many people in their 60s as in their 20s.
Of course all the comments debate why that's even a problem.  Back when I took economics classes, only a few, they didn't go into that, because it hadn't started yet. There seemed to be a normalcy and benefit to continually expanding economies, which of course the US doesn't experience in the same way now, if at all. Japan seems to be the test case for all this but I personally can't piece together active causes and effects there, even though it's clear that it's not going well. >


People are living longer healthier lives and are (or should be) saving to finance their retirement.

This is a fundamental misunderstanding of economics. Economics is about the production and distribution of goods and services. You need young people to do the actual production and distribution: working the farms, becoming electrical contractors, writing the code, cooking at the restaurants, staffing the nursing homes. The old people can be financially independent, but without people actually making the stuff you just end up with too much money chasing too few goods, i.e. inflation. Money can't make stuff get produced, it's a means of facilitating transactions. 

First, I don't buy a population decline would be permanent recession, particularly on a GDP per capita basis, which is the true metric we should be focused on.

GDP per capita is important, but sometimes raw output matters too. Denmark has a similar GDP per capita to the US, but is basically irrelevant in the current trade wars with China or ability to kick Russia off of SWIFT. We won World War 2 because nothing could match our absurd industrial capacity. Detroit produced more Shermans in one day than Tigers produced during the entire war. We went from 1 to 71 escort carriers and 7 to 28 fleet carriers over the course of WWII. You can't win a war against that kind of raw output. That's GDP, not GDP/capita. >


You need young people to do the actual production and distribution: 

Let's take a look at each of these examples.

working the farms

Most farming has become industrialized and automated and continues to move in that direction.

becoming electrical contractors

Better electrical equipment means less need for electricians. Also, depending on what it is a lot of boomers (or their children) do this work DIY.

writing the code

The thing with programming is that it has immense scale relative to the amount of work put in. An electrician or nurse may be constrained by how many customers they can serve but a programmer isn't.

cooking at the restaurants

Price of dining out goes up, more people eat at home. This is a self-balancing mechanism. But I'm not too concerned about this since I get take out all the time because it's often the same price or cheaper than cooking it myself.

staffing the nursing homes

The unhealthy will die before they get to the nursing home. The healthy habits and new innovations will enable a higher level of independent living for seniors, particularly since they own all the real estate anyways. >

The examples were less important than the concept. I'm sure in 30 years the job mix will be as unpredictable as the current mix was in 1990. Of course to some degree capital can substitute for less labor, but not entirely and certainly not in areas like cleaning bedpans or being doctors. Besides, the thing we want capital to do is augment labor, increasing total factor productivity, not just substitute for it. If it's hard to maintain current output with less workers, growth is dead. 
If growth is dead, well, everything gets harder. Federal insolvency becomes much harder. Managing climate change becomes much harder. Imagine if we had grown at 1% less for the past 30 years, and Zoom was still 15 years out when the pandemic hit. Richer societies handle basically every problem better than poorer ones. >

so instead of actually intellectually reading through each argument and breaking it down logically, a lot of them you just struck down with your own straw-man, emotional, opinionated response? seems like not the best way to go about wanting someone to change your view. >

Population decline means that food becomes more expensive because there aren't enough farmers to produce enough food. Going anywhere becomes more difficult because there aren't enough engineers and construction workers to build and maintain infrastructure. Getting medical treatment becomes more difficult because there aren't enough nurses and doctors. Your quality of life in every aspect will decline with fewer people around. >

Innovation comes from a well educated population. Not from a large population. There are a ton of innovations going on in small population countries. Nobel prizes per capita would be one metric to look at. And with a smaller population there would be less strains on the system as a whole so less need to focus innovative capacity to alleviating those strains and more focus on revolutionary innovations.
What a brain-dead take. Innovation comes from a well educated population yes, and the larger that well educated population is the more chances there are for innovators to be in it. 
I'd say most of your problems in comprehension come from this inability you have to understand that more people working on something can do it faster than one. That more people can do more things than one person. Its pretty simple if you stop thinking out your ass.