I have just read a debate about whether high-IQ kids should be allowed to attend special schools, and the debate was predictable. So I used this as an opportunity to summarize the arguments against "smart segregation". (The arguments in favor of it seem quite straightforward: better education, less bullying, social and professional company of equals.) Here are the results; please tell me if some frequently-made argument is missing.

Note: different arguments here contradict each other, which is okay, because they are typically not made by the same people.

1 -- There is no such thing as "smart children", because...

1.A -- ...everyone who believes to be smart is actually just a conceited fool. Parents who believe that their children are smart are just typical parents uncritical about their children. (Insert anecdotal evidence about a kid from your elementary school who believed to be super smart, and so did his parents, but he was obviously a moron.)

1.B -- ...you cannot measure smartness on a single scale. There are many kinds of intelligence; everyone is special in a different way. Someone is better at math, but someone else may be better at dancing or spirituality. Belief in g-factor is debunked pseudoscience; it is racist and sexist and shouldn't be given a platform. (Quote S.J.Gould and/or insert example of Hitler believing some people were better than others.)

1.C -- ...you cannot measure smartness fairly. If a child is tested as smart, it only means they have rich parents who were able to buy them tutors, made them cram for the tests, and maybe even bribed the test evaluators. Also, it is known that tests provide unfair advantage to white cishet male children.

1.D -- A weaker version of the previous statement is that if you make programs for smart children, the children from poor or minority families will not be able to participate in them, for various reasons. This would leave them in a worse situation than they are now, because if it becomes a common knowledge that such programs exist, the fact that the child didn't participate in one would be taken as an evidence against being smart. That is, an average smart child would be actually harmed by such policy.

2 -- Having smart children together with dumb ones is better for the smart children, because...

2.A -- ...it will improve the smart children's social skills. The most important social skill is to be able to interact with average people, because they make a majority of the population, so you will interact with them most frequently as an adult. (This assumes that adult people actually interact with a random sample of population, as opposed to living in a bubble of their profession or socioeconomical level, both in professional and private lives.)

2.B -- ...it will allow the smart children to learn important things from the dumb ones, other than the academic skills. (This usually assumes some kind of cosmic justice, where smaller intelligence is balanced by greater emotionality or spirituality, so the dumb children can provide value that the smart children would not be able to provide to each other.)

2.C -- ...it will allow the smart children to have contacts outside of their bubble.

2.D -- ...the smart children can tutor the dumb ones, which will be an enriching experience for both sides. Explaining stuff to other people deepens your own understanding of the topic.

3 -- Having smart children together with dumb ones is better for the dumb children, because...

3.A -- ...having the smart children in the classroom will provide inspiration for the rest of the class.

3.B -- ...the smart children can tutor the dumb ones.

3.C -- ...it will allow the dumb children to have contacts outside of their bubble.

3.D -- ...the smart children in the classroom will motivate the teachers; having motivated teachers at school will benefit all students.

3.E -- ...the parents of the smart children (presumably themselves smart and rich) will care about improving the quality of education in their child's school, which will benefit all students.

4 -- We should actually not optimize for the smart children, even if it would be a net benefit, because...

4.A -- ...the whole "problem" is made up anyway, and a truly smart child will thrive in any environment. Optimizing for smart children should be such low priority that you should be ashamed for even mentioning the topic. (Insert anecdotal evidence about a smart kid who studied at average school, and became successful later.) Even the argument about bullying is invalid, because bullying happens among smart children, too.

4.B -- ...smart children usually have rich parents. Creating better educational opportunities for smart children therefore on average increases income inequality, which is bad.