Professor Plantinga is known for distinguished work in the fields of epistemology and philosophy of religion. In this companion volume to Warrant: The Current Debate, Plantinga develops an original approach to the question of what justifies belief and makes it knowledge. He argues that what is crucial to turning true belief into knowledge is the "proper functioning" of one's cognitive faculties, and this clears the way for the proposal that a belief is warranted whenever it is the product of properly functioning cognitive processes. Although this is in some sense a sequel to the companion volume, the arguments in no way presuppose those of the first book and it can therefore stand alone.