 Even once it is agreed that good simpliciter is incomparable in this sense, many theories have been offered as to what that incomparability involves and why it exists. One important constraint on such theories is that they not predict more incomparabilities than we really observe. For example, though Rodin may not be a better or worse artist than Mozart, nor equally good, he is certainly a better artist than Salieri — even though Salieri, like Mozart, is a better composer than Rodin. This is a problem for the idea that incomparability can be explained by value pluralism. The argument from value pluralism to incomparability suggested that it would be impossible to compare any two states of affairs where one contained more of one basic value and the other contained more of another. But cases like that of Rodin and Salieri show that the explanation of what is incomparable between Rodin and Mozart can’t simply be that since Rodin is a better sculptor and Mozart is a better composer, there is no way of settling who is the better artist. If that were the correct explanation, then Rodin and Salieri would also be incomparable, but intuitively, they are not. Constraints like these can narrow down the viable theories about what is going on in cases of incomparability, and are evidence that incomparability is probably not going to be straightforwardly explained by value pluralism.