Routledge Encyclopedia Of Philosophy
Contrastivism about knowledge is the view that one does not just know some proposition. It is more adequate to say that one knows something rather than something else: I know that I am looking at a tree rather than a bush but I do not know that I am looking at a tree rather than a cleverly done tree imitation. Knowledge is a three-place relation between a subject, a proposition and a contrast set of propositions. There are several advantages of a contrastivist view but also certain problems with it.
Taylor And Francis
Routledge Encyclopedia Of Philosophy.