ABSTRACT
THE argument just gone through in Chapter 9 applies to an indefinite number of kinds of mental acts and psychological states and occurrences. As stated there it referred only to judging. But with appropriate changes it can be applied to thinking, reasoning perceiving, imagining or questioning. What we have is a schema of proof which, by proper substitutions, can be made into a proof that thinking in sleep, reasoning in sleep, imagining in sleep and so on, are all unintelligible notions. The things just mentioned are all examples of mental activities, but this is not essential to the proof. It works just as well for ‘passivities’ like fear, anxiety, joy; illusions and hallucinations; and imagery.
