Can you prove that frozen custard and ice cream are different types of food?
Of course, by definition they are different types of food, with the dividing line being 1.4% egg yolk solids. But one might notice that this dividing line is completely arbitrary, the universe doesn't care about it at all, and there is in fact a smooth continuum between "ice cream" and "frozen custard" and you can make food anywhere along that spectrum.
Some thing with species. Yes, chimps and gorillas are clearly different species according to how biologists define species. (There is some dispute over how exactly you define a species, because obvious definitions like "groups which interbreed to produce viable offspring" don't always produce sensible results, but chimps and gorillas are far outside the unclear areas.) But that doesn't mean that "species" is some inherent property in the world, it's just a useful device for categorizing it.
Sure, but so what, the point is that those are arbitrary human labels.
I certainly wouldn't go around expecting them to make a baby based on what I've said, I just phrased things the way I did to try to emphasize the above point.
