Belief and knowledge

It is often said that for people to know that such and such is the case, they must have something like a belief that such and such is the case. Call this the ‘entailment thesis’. It is usually added that the converse (call it the ‘converse entailment thesis’) is false: it is false that my belief-like attitude that such and such is the case always counts as knowledge. This standard view, combining the entailment thesis with the denial of the converse thesis, has been challenged in a number of ways. The ‘identity thesis’ would retain the entailment thesis but would also endorse the converse entailment thesis. Knowledge and belief entail each other. (While no one has defended precisely this claim, Donald Davidson has come close.) The ‘incompatibility thesis’ rejects the entailment thesis as well as the converse entailment thesis, and says that knowledge and belief are mutually incompatible. Similarly, the ‘separability thesis’ also rejects the entailment thesis and the converse entailment thesis, but adds that knowledge and belief are mutually compatible. Those who defend the ‘eliminativism thesis’ hold that belief, like other elements of ‘folk’ or popular psychology, is an outmoded notion, and what is ‘in our heads’ when we know about the world is something other than beliefs.