Russell Hardin describes an economic theory of what people “know” (I keep wanting to substitute “believe” for “know”).

we can explain bits of knowledge that a given person has as being substantially affected by the costs and benefits of obtaining and using those various bits. Moreover, we can explain the retention of bits of knowledge in the face of competing knowledge by the seeming costs and benefits of retaining them, balanced against the costs and benefits of revising or rejecting them.

There is more to it than that. Pointer from Tyler Cowen.