I may have been incorrect regarding the essence of beauty. That it is subjective real, I maintain. But what is the essence of subjectivity?
There are two possibilities. First, that there is no wrong answer regarding what is or is not beautiful. If Smith says X is pretty, and Jones disagrees, then there is no way to adjudicate the dispute, find out who’s right and who’s wrong.
The second possibility is more subtle. Perception of beauty is a wisdom, and a person is either objectively wise or objectively foolish. Subjectivity in this understanding means that the ranking of beautiful things is ordinal and not cardinal.
Thus, 7 is greater (or “better”) than 5 by an exact value, 2. The distance between 7 and 5 can be measured and ascribed a precise cardinal value. But such a value cannot meaningfully be found between the beauty of painting X and music Y. Even though X is more beautiful than Y, we cannot tell by how much.
Just as in economics we reject the idea of cardinal “utils,” so in aesthetics, we do not deal with “beautils” or anything of than sort.
Even though the “experiences of each moment are incommensurable” speculatively, they become so in the process of choice. One experience will have to be judged superior to the others. Therefore, as to how to decide whether Smith or Jones is right and X is, in fact, prettier than Y, we can do this, to reiterate, by looking at how happy Smith and Jones actually are. Happiness can be compared intersubjectively through love of friendship.
Update. Beauty then is subjective in the second sense but not in first; pleasure is subjective in both senses: if Smith feels more pleasure from Q than from P, then that’s the end of it: Q is better than P (for him), and there are no ifs, ands, or buts about it.