 We have already seen that some theorists take knowledge to be the (or at least an) aim of belief. Some philosophers go further and say that knowledge is also the norm of belief - that is, that any belief that does not also count as knowledge is impermissible or irrational or vicious or defective. Put another way: knowing that p is both a necessary and a sufficient condition for permissibly (rationally, virtuously) believing that p. 