Reasoning with Uncertain Beliefs

This chapter describes the reasoning with uncertain beliefs. There are circumstances in which it would not be appropriate for an agent to invest its beliefs with total commitment. An agent may realize that not only does it merely believe P instead of knowing P , but that it does not believe P strongly. There are many situations in which humans possess and reason with uncertain beliefs. In searching for ways to formalize the idea of beliefs having strengths, one are tempted to consider a generalization of logic in which truth values can take on values intermediate between true and false. To believe P with total commitment is to assign it the value true. To disbelieve P totally is to assign P the value false. Inventing truth values between true and false allows for various degrees of partial belief. Multivalued logics have been studied sometimes with this application in mind.