Fact 1: Babies have been observed to look at pictures of people that most would agree are beautiful longer -> objective.
Fact 2: Not everyone agrees on Rihanna -> subjective.
Conclusion: beauty is both. Deal with it.
Agreed, when I saw this thread my first thought was about the studies showing babies will look at a symmetrical (which is how a face is judged for beauty sub conciously) face longer than they will an unnatractive one.
I think the idea of beauty is the more universal truth in the end though, since ^^ this is not a hard and fast rule once cultural ideas of beauty change what that baby was looking at when it was too young to be socially conditioned.
Then, it is not what looks right, but rather the fact that people create a standard of beauty for everything that is universal.
What defines that beauty is subjective on the other hand. In the West scarring is ugly, yet some parts of the world they scar themselves and those scars become part of the attraction process. "oh look at that warrior and his spear, what a mighty fine scar on his cheek that he has"
Or like rendevous said, the whole long neck fashion, or the plate in the lip. To us that stuff looks unnatractive (well to me it does) but to them, that is beauty.
Maybe as a baby they had a universal reaction, but life = subjectivity. No universal truth then.