 A final line against SK is that, if (1) is not apriori (as is plausible), it follows that apriori knowledge of (2) is impossible (Gertler 2004). After all, if (1) is not apriori, then Oscar apparently cannot discriminate apriori between his water concept and the Dry Earthian concept. So it seems incorrect to say that (2) is something known. Now in fact, this raises the extremely important question of whether such discriminations are necessary for self-knowledge, but further discussion will be delayed until section 3. The discrimination sub-literature usually addresses the “slow switching” arguments rather than the incompatibilist’s reductio.