Incommensurateness is vagueness

We often encounter pairs of objects where neither seems better than the other, and yet they do not seem to be equally good. I say they are incommensurate. The aim of this chapter is to argue that incommensurateness is no more than the vagueness of comparative relations such as betterness. Other relations besides betterness exhibit incommensurateness. For example, we may encounter two colors where neither seems redder than the other, and yet they do not seem to be equally red. I provide two arguments neither conclusive that support the view that incommensurateness is generally vagueness. Then I consider betterness in particular. This is a practically important relation because of its connection with normativity. On the basis of this connection with normativity, I provide a further argument in support of the view that the incommensurateness of betterness is vagueness. The argument is that vagueness provides the best account of a classic normative problem that is raised by the incommensurateness of betterness.