Comment by Arainach

The main researchers associated here are Samir KC and Wolfgan Lutz. Their latest update (with a long list of coauthors) is from 2024 [1]; this is a followup of the important 2013 paper [2].

[1] https://pure.iiasa.ac.at/id/eprint/19487/1/WP-24-003.pdf

[2] https://papers.ssrn.com/sol3/papers.cfm?abstract_id=2344470

I don’t have any structured references saved, sorry.

My understanding is that the only real correlation is years in education, but this is at the national level; the very rich and very poor (which imperfectly correlates with level of education attained) tend to have more children than the middle class, but fertility rates are down across every income level. What this means is that if you look at two countries and see that one has a higher level of education than the other, you would expect the country with the higher level of education to have a lower fertility rate, but within both countries you would expect to see a relatively uniform decline in fertility across every income level, with a more pronounced decline around middle income levels.

This is maybe what’s being referenced when people saying they’ll have kids when capitalism gets sorted, but this isn’t seen in countries where standards of living have improved considerably.

The simplest theory is that more people are using contraceptives because they simply don’t want children. Some people might subjectively feel like they can’t afford to have children, but by world historical (and contemporary) standards of living this argument looks incredibly silly.

> we'd prefer a 3 bedroom but they DO NOT EXIST

This seems to be an absolute epidemic across the state. Same with condos. It's like they assume that apartments of any kind are only for single people and maybe a couple with one child. In other words, people who are dragging the fertility rate down toward 50%.

When I pull up Zillow and look at rentals across a huge swath of the East Bay, there are 8,309 apartments listed (I filtered out houses and townhomes). I add one filter: 3+ bedrooms. The number drops to 784. Fewer than 10% (!) of apartments listed have 3+ bedrooms. (Also, a quick spot check of these seems to show a nontrivial amount that are actually just houses with faulty metadata.)

This puts a tremendous burden on low-income people, to have to foot the higher cost of maintaining a home and/or of an absurd commute, just in order to have enough space[1] to have more than one kid. That, or overpay to compete for one of the few bigger apartments, many of which are "luxury" oriented.

Meanwhile, the high-income can afford a house or a luxury 3br apartment, but they are mostly high-income because they've deprioritized family, putting in 10+ years of being DINKs. In my circle of upper middle class tech types, many of them are 35-38 before having their first kid. 1 kid is much more likely than 3 for people starting in their late 30s, so this drags down fertility rates even among the "high income" subgroup!

[1] I know opinions vary on whether it's good and healthy to have kids sharing rooms, though imho I don't want a son and daughter forced to bunk together as they get older, and calls to 'just share rooms' is giving "Own nothing and be happy."

For what it's worth, we had our first child when we lived in a studio in our late 20s. One kid is really easy space-wise. The only reason we even got a 2BR before buying our house is that we got an au pair.

This did not stop people in the past. You read of three-room New York tenements holding families of ten, or families with half a dozen children living in a single-room frontier cabin, and this was considered commonplace.

My parents raised eleven children in a typical four-bedroom suburban tract house.

I wonder why modern people would be different?

Raised 3 kids in a 2 bedroom apartment in NYC. It’s fine. When they go to college, they marvel at the space they have in a dorm room.

The high cost of childcare also largely comes back to high rents. The management needs to pay for the space, and pay workers enough to afford to live within commuting distance. There are of course other costs to running a day care center (utilities, insurance, supplies) but rent is a major factor here.

The rates are plummeting everywhere. Even countries that have 3 or 4 kids per woman used to have 5 or 6 and are on pace to drop below replacement within 15-20 years.

Look at slide 3 again ("TFR around the world").

By 2075, Medicare and Social Security will reach a over 14% of GDP combined, up from around 8% today. To pay that, we'll have to raise taxes by $1.75 trillion using today's GDP figures. That will require just about doubling payroll taxes from the present level.

That's probably an underestimate. As population shrinks, GDP will shrink as well, unless we have large gains in productivity, which have stalled. It's not clear to me that the projections about SS/Medicare as a percentage of GDP account for the effect of GDP shrinking due to population decline. CBO assumes a stable population through 2060, using quite arbitrary assumptions about immigration: https://www.cbo.gov/publication/60875.

That presumes knowing in advance what the dollar can buy you.

Here's a reductio ad absurdum: a couple live alone on an isolated island, they have and raise one child, and when they reach 67 they stop working and expect their progeny to provide for them as they were provided for in childhood.

Two parents provided for three people, became three adults providing for three people, became one adult providing for three people.

And when that kid reaches 67 and also decides to stop working? Now nobody's around to provide for them, so nothing is provided.

(What will happen in the non-reductio case is much more complex and unpredictable, between the never-ending potential of nuclear wars, and the ongoing but never guaranteed promise of technological progress currently dangling AI and robotics before us like a laser pointer to a cat…)

In 2003 the average fertility rate was around 2.03

It started falling to 1.6 around 2008 ( https://www.macrotrends.net/global-metrics/countries/usa/uni... ) which coincided with the millennials getting into the child-bearing age. And the millennials are much more likely to live in cities, even though they don't want that: https://news.gallup.com/poll/245249/americans-big-idea-livin...

It's a well-known phenomenon. E.g.: https://link.springer.com/article/10.1007/s10680-008-9163-9

It's been eroding lately, but mostly because fewer younger people can afford to live in suburbs. By "afford", I don't mean monetary cost, but the lack of easily accessible jobs.

I'm investigating that, and I believe that it's even _worse_ than the simple fertility rate shows. If you look specifically at the number of parents with two or more children, suburbs completely demolish cities when you control for the average income.

Controlling for the average income is needed because of the two poles of fertility: desperately poor people, and happy content people ("reversed J-curve"). And cities in the US disproportionally concentrate desperately poor people.

It's not just rent, it's also transportation. Transporting young kids with a car is easy, public transportation is much harder until they are 10 or so.

For example try transporting a sleepy kid, or more than 1 young kid at the same time.

Cities are cars don't get along very well, which makes them less friendly to kids.

Suburbs are really nice for kids, basically zero car traffic, you can play in the street, easily go to parks. And when the parents need to take you far you have a car available.

Suburbs might not be friendly to children but they're quite friendly to the parents of small children. When you're pressed for time and need to cook dinner or something it's super convenient to be able to send the kids into the back yard or their own separate bedrooms, knowing they'll be fairly safe and contained for a while.

Remote work is a great option for many people but it simply isn't feasible for any job that can't be done through a computer. We should set economic policies that encourage job growth in suburban and rural areas rather than trying to squeeze everything into a handful of dense cities.

And you'll be doing them, whether you like it or not.

Have you noticed the massive growth in government? You're paying for it, one way or another.

Inflation is caused by the government via deficit spending. It's another tax on you.

Do you think the population of the US is all from immigration and rich people?

(A relative worked out our family tree. Lots of families with 8 kids in them.)

> A moment's thought will make clear why.

Take a moment and elaborate, please.

It's a fact, not a theory. The wealth in the economy did not exist 100 years ago. Therefore it must have been created.

And where did Musk's money come from? Who did he transfer it from?

> Is there an upper bound to the creation of wealth?

No

> Is it infinite?

Yes

> Are there any limits to its creation?

Government trying to crush it.

> Is there any inherent value to it without being able to "transfer"?

The only value it has is what someone else is freely willing to pay for it. There is no such thing as "inherent" value.

It has figured out how to make better use of the land.

Transactions based on free negotiations, not force or fraud.