At any given university, the kids from public schools are smarter

Note that here we're talking about something different - namely, that _at any given university_, the kids from public schools are smarter than the kids from private schools. We don't talk about all kids - only kids in universities, and there is selection filter for who gets there, so in universities the distribution of "smartness" for private or public school kids is different than in schools.

In other words, maybe you're right and the average private school student is smarter than the average public school student. But it's not the average student who gets to a university.

There was once a stable state when many universities had several candidates for each place, and could choose whom to admit. Theoretically, the better the university the bigger the pool of candidates it has. However some universities were notoriously hard to get to, so candidates didn't even bother to apply there. As a result, the candidate pools in those universities were smaller, but those candidates were of a different kind - as if they have already passed pre-filter which made them more confident that they are those special ones who has better than average chance to get to those hard to get universities.

These are also countries with high prevalence of private, after school tutoring (i.e. so-called shadow education). For example, as of 2013 more than 40% of Italian secondary students attend private lessons. See Table 1 at https://journals.sagepub.com/doi/full/10.1177/20965311198901... And in Turkey this figure was nearly 60% in 2003, which may very well be even higher today (or at least # of hours is probably higher). See Figure 4.1 at https://etd.ohiolink.edu/apexprod/rws_etd/send_file/send?acc...

Not going to bother posting figures for Japan and South Korea as I don't think anybody disputes the prevalence of tutoring in those or other East Asian countries.

If you want to prevent richer (either financially or in parental involvement) kids from getting ahead, you literally need to suppress their ability to capitalize on those assets. Such as China is doing by regulating tutoring companies, or woke school boards are doing in various U.S. cities and universities. Of course, arguably you're merely hiding the underlying inequalities. But I guess this is just Goodhart's law in action, combined with pursuing the path of least resistance. That is, far easier to pursue a metric reflecting a consequence of economic inequality rather than metrics more directly measuring that inequality (e.g. Gini coefficient), let alone addressing the underlying causes themselves.

You also only get 1 shot at applying to a public high school. So students tend to self-select (with some not-so-subtle nudging by their teachers) on the tier of public school they apply to based on various assessments of their own academic prowess.

This creates a competitive environment for the top tier public high schools, which feature heavily subsidized and reduced tuition. Yes. You must pay for high school in Japan. And competitive high-performing high schoolers tend to apply for and get into competitive, top tier universities such as Tokyo Universities.

Parents and high performing middle school children understand this acutely. So naturally, an entire industry of cram schools emerges to prepare these precocious 14 year olds to apply to the best high schools in their region so they can go to the nation’s best university so they can work at the nation’s best companies and live a life of middle class comfort.

On the other hand, private schools largely will overlook test scores in exchange for the more expensive tuition collected. As far as I can remember, you were also only allowed to apply to one private. Not to say privates are bad, or that kids don’t want to go to them. But the high performers definitely were going for the publics with the private school being their backup.

As a result, Japanese middle school students are some of the most stressed out teenagers I’ve ever seen.

Most public high schools don't have AP or IB courses and the ones that do tend to have them in limited supply in the hard sciences ( i.e. AP Physics C, AP Computer Science A, etc). Pursuing some sense of rigor involves taking courses that seem difficult rather than taking them in the hopes of forming a more cohesive understanding for one's future pursuits. Self-teaching obviously helps quite a bit, but that doesn't aid most students in achieving a firm foundation for say, undergraduate research in Physics.

Some private schools have high admission standards, and these have better teachers and more motivated students than comparative public schools in the area. The existence of these counter-examples shows that Graham's reasoning doesn't hold. He also assumes that the public school students have studied less material, or easier material, than private school students, and are more motivated to learn. This isn't guaranteed; certain public school programs (like IB, mentioned by another commenter here) meet or exceed the curriculum standards by other private schools. In short, the wording of the Tweets in their current form demonstrate weak reasoning.

However, to take a more charitable interpretation, it's true that other private schools let anyone in who can pay the tuition, while also having less dedicated teachers and unmotivated students compared to public schools (especially public schools with high admission standards). Using more precise language, it can be altered to roughly: "motivated but less-privileged students can outcompete less motivated, more-privileged students in university."

This is a more interesting assertion, but it also depends on the amount of privilege (e.g. some privileged students get an apartment with near-zero commute to the university, lots of cash, the best tutors, etc.). Life isn't truly meritocratic, but you try to do the best you can with the cards you're dealt.

I get this feeling reading a lot of 'insightful' Tweets, especially written by Paul Graham. His essays have been influential and useful, but his Tweets were disappointing (flawed arguments, emotional appeal) to the point where I unfollowed. It's just Twitter, but it does feel like a missed opportunity for a truly insightful feed.

I personally think this is an interesting thought experiment—albeit also one with a lot of flaws. What if the kids from private school are smarter because the private schools have better instruction? Or what if only smarter kids are accepted into private school, as private schools have a (frequently competitive) admissions process, whereas public schools have to take everyone.