Perception

Having a percept with content P P

Are the circumstances such that having a percept P is not a reliable indicator of P? Memory

Recalling P P

Is P originally based on beliefs of which one is false? Is P not originally believed for other reasons? Does the agent who recalls P express doubt about P? Statistical Syllogism

c is an F F's are usually G's c is a G

Is it the case that, 'c is also an H', and 'things that are also H are not usually G'? Induction

Most observed F's are G's F's are usually G's

Temporal persistence

P is believed to be true at T1 T1 is before T2 P is true at a time T2

Is not-P true at some T3 between T1 and T2? General Knowledge

It is general knowledge that P P

Witness Testimony

Witness W says P P

Is witness W truthful?