Perhaps not the best arguments; it is a fact that the keyboard under your fingers reflects only in certain components of the electromagnetic spectrum. That you choose to denote the absorption profile of your keyboard as "black" is simply down to semantics. Can we prove that I see black in exactly the same way as you see black? No. But that does not mean that we cannot make an independent measurement on which we both agree a result.

Equally, I don't think that you will find argument from two people with functioning tastebuds that your milk has gone off. Whether you enjoy the taste is a somewhat different point. On this, however, the point is slightly different because not-very-well-aged milk could taste "on the turn" to one person and "completely fine" to mendhak. Nevertheless, a chemical analysis of the milk would reveal a set of results that both parties can agree to without the question of perception arising.


Ultimately, I guess I'm saying that it boils down to bucketing. That different people can discern finer levels of detail than others is beyond dispute, so that what you bucket as "black" others may bucket as "very dark blue" or "very dark green" etc. Nevertheless, given the numbers behind the perception, you will find that you can reach agreement with the next man.

Which leads us to the origins of the word "science"......