Cumulative Record. Chapter 20: What Is Psychotic Behavior? Quote 16

Philosophers have often insisted that we are not aware of a difference until it makes a difference, and experimental evidence is beginning to accumulate in support of the view that we should probably not know anything at all if we were not forced to do so. The discriminative behavior called knowledge arises only in the presence of certain reinforcing contingencies among the things known. (p. 317)