https://en.wikipedia.org/wiki/I_know_it_when_I_see_it

https://en.wikipedia.org/wiki/Duck_test

https://en.wikipedia.org/wiki/Pragmatic_maxim

There’s more genetic variation within any so-called racial group than between groups, so race obviously has no genetic justification. It's real in the way other social constructs are real.

aka "a category that appears self-evident to me".

This was my thinking, also. Good cluster of links.