Qualifiers such as “insofar as” and “in itself” have always been important ingredients in key philosophical claims. Descartes, for instance, famously argues that insofar as he is a thinker, he is not made of matter, and Kant equally famously argues that we cannot know things in themselves. Neither of these claims is meant to be true without qualification. Descartes is not simply denying that humans consist of matter, and Kant is not simply denying that we know things. Therefore, we cannot (...) even begin to understand such claims without knowing how qualifiers work. Unlike the logic of quantification, however, the logic of qualification is rather underexplored. In this paper, I examine several instances of philosophical uses of qualifiers, taken from Aristotle, Avicenna, Descartes, Kant, and 20th c. action theory. In the light of these examples, I discuss several accounts of how such qualifiers work. (shrink)