I got to thinking about names of colors, and I wondered if there is only one shade of black or white and the different names used for them are describing the same colors, or are there different shades of these colors?
You mean like the various shades of gray?
Theoretically, they’re absolutes.
Practically, there are are various shades.
Practically: Go to any store that sells house paint. Especially the Interior shades. You will find many blacks & whites!
Bingo. I remember once trying to decide between “White,” “White White,” and “White on White.”
There’s another side to this. If you’re talking about the color of an object because of the light it reflects, then there would be an ideal black that reflected nothing and an ideal white that reflected everything. But, if you are talking about the color of something that actually creates light, like the color of a light bulb or a neon sign, then while black is still uniquely defined, white would always have some surface brightness, and there wouldn’t be any one special version of it.
Another point: when talking about chromaticity, there are various versions of white, and no one single magical reason to prefer one over all the others, though there are various special properties of some of them.