ABSTRACT: IDiversity matters – theoretically and practically, within philosophy and beyond. It is less clear, however, how we are to conceive of diversity. In current debates it is quite common to discuss diversity as a diversity of social identities. In this paper, I will raise five major concerns with regard to this approach from a philosophical perspective. All of them cast doubt on the flexibility and openness to ambiguity of identity-based concepts of diversity. Contrary to an identity-based concept of diversity, I will propose a perspective that stresses ambiguity and fluidity. In pursuing my argument, I will, after an introduction in §1, outline in §2 how the term ‘diversity’ is commonly used and how social identities come into the picture. In §3, I describe the dangers of an identity-based diversity concept. In my critique I will build on Adorno’s thoughts on the formation of concepts and on Appiah’s reflections on identity. I will illustrate my critique with examples from a growing field of Applied Ethics, data ethics. In §4, I will sketch an alternative understanding of human diversity, taking up considerations by Thomas Bauer on ambiguity and ambiguity tolerance.