Contrastivism, or the contrast theory of meaning, is an epistemological theory proposed by Jonathan Schaffer that suggests that knowledge attributions have a ternary structure of the form 'S knows that p rather than q'.
This is in contrast to the traditional view whereby knowledge attributions have a binary structure of the form 'S knows that p'.
Walter Sinnott-Armstrong proposed in a paper titled "A Contrastivist Manifesto"[1] a variant of contrastivism that, he argues, differs from contextualism, invariantism, and Schaffer's contrastivism.
Rather than taking the same road as contextualism and saying that the meaning of 'knows' can change with attributor context the contrastivist claims that it is the unspoken contrast clause that changes.
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