In our every waking moment, and even in some sleeping ones, we must distinguish between what is true, and what is not. How do you determine whether your sensations reflect reality? How do you criticize the ideas that pop into your head? What do you do when presented with claims about real world from other people? Under what circumstances do you regard them as false? Under what circumstances do you regard them as true? What are the conditions that you think should make other people regard a claim as true or false?