Contrastivism is the view that knowledge is a ternary relation between an agent, a content proposition, and a contrast, and it explains that a binary knowledge ascription sentence appears to be context-sensitive because different contexts can implicitly fill the contrast with different values. This view is purportedly supported by certain linguistic evidence. An objective of this paper is to argue that contrastivism is not empirically adequate, as there are examples that favor its contextualist cousin. Thereafter, I shall develop a contextualist (...) account for the relevant linguistic data. The account consists of a contextualist semantics and some rules of pragmatics. The two parts combined show that contrastivism is neither sufficient nor necessary as a satisfactory theory of knowledge ascriptions. (shrink)