  In view of its apparent consequences for the theory of evidence, the idea that one's evidence is the same in the good case and the bad case warrants further scrutiny. Again, it is uncontroversial that there is a robust distinction between nonculpable error on the one hand and irrationality or unreasonableness on the other. Nonculpable error does not in general make for irrationality, even when such error is relatively widespread and pervasive. Still, it's worth asking just how much weight the distinction in question can bear. Is any amount of nonculpable error about the environment in which one is embedded compatible with perfect rationality? Or rather, at some point, does a sufficient amount of error about one's environment tend to compromise one's ability to form rational beliefs about that environment?