>>7620526In short, he's a realist. He's almost the same kind of person that would have complained hundreds of years ago, saying "these imaginary numbers are bullshit - you cannot show me 3 = 5i apples!".
As far as I can tell from spending a day or so watching his videos, he has a willful misunderstanding or denial of the basic rules of ZF set theory. In particular, the IMHO best way to understand ZF set theory is that it lays out some starting assumptions in symbolic form, does not ascribe any particular meaning to the symbols, and it gives allowed rules of deduction and inference. Then, go nuts. You can take the starting premises and the rules of deduction, and then you can derive other things. It's a wholly unambiguous framework. Very formal.
Wildberger detests this view because in his world, the only true mathematics is that which has some exact 1 to 1 relation to the real physical world, and anything else is rubbish. He's the worst kind of realist / Platonicist.
Note: He will make exceptions for imaginary numbers because it can be done as a simple field extension, and for whatever reason he's ok with field extensions of a finite number of extensions. But oh no - can't close the rationals over "least upper bounds" - because reasons.