 What can this alleged symmetry amount to? One idea is that we have the same evidence in both cases. According to a Cartesian account of this common evidence, it consists in mental states of the subject, such as her experiences. By construction, the subject has the same experiences in the skeptical scenario as she does in the good case. But some philosophers, most notably Williamson 2000, have denied that we have the same evidence in the good and the skeptical case. According to Williamson, our evidence is constituted not by our experiences, but by what we know. Given that in the good case we know more propositions that in the bad case, we have more evidence in the good case than we do in the skeptical case. In the good case, for instance, we know mundane propositions such as the proposition that we have hands. Given that knowledge entails justification, in the good case we are justified in believing that we have hands. Given CP, in the good case we are justified in believing that we are not in the skeptical case. This account of evidence entails that the relation of indiscriminability between the good case and the skeptical case is not symmetric: victims of a skeptical scenario cannot distinguish the skeptical scenario from the good case (for all they know, they are in the good case, and for all they know, they are in the skeptical case), but subjects in the good case can distinguish between the cases (they know that they are in the good case, and—again, given CP—they know that they are not in the skeptical  case).[16]