Finally, some theorists have suggested that the context-sensitivity of sentences involving ‘know’ is owing to a more general context-sensitivity in certain explanatory relations and claims. For example, Steven Rieber (1998) has proposed that, in general, S knows that P iff “the fact that P explains why S believes that P” (1998, 194). According to Rieber, however, explanations are always at least implicitly contrastive, and whether one thing explains another will depends upon which contrasts are salient.[9] As just presented, Rieber’s theory concerns the knowledge relation itself; so, in the terminology of Section 1, it would qualify as a substantive contextualist view. But Rieber’s is clearly better construed as a semantic theory, like the other views just sketched. For, as applied to SA, it would have the consequence that what the conclusion of that argument in effect says is something like: