In this companion volume to Warrant: The Current Debate, Plantinga develops an original approach to the question of epistemic warrant; that is what turns true belief into knowledge. He argues that what is crucial to warrant is the proper functioning of one's cognitive faculties in the right kind of cognitive environment.

1. When we attribute beliefs, desires, and other states of common sense psychology to a person, or for that matter to an animal or an artifact, we are assuming or presupposing that the person or object can be treated as an intentional system. 2. An intentional system is one which is rational through and through; its beliefs are those it ought to have, given its perceptual capacities, its epistemic needs, and its biography…. Its desires are those it ought to have, (...) given its biological needs and the most practicable means of satisfying them…. And its behavior will consist of those acts that it would be rational for an agent with those beliefs and desires to perform. [beliefs + desires  action] 3. If rationality is absent, we cannot coherently ascribe beliefs at all. 4. Therefore, no experiment could demonstrate that people systematically invoke invalid or irrational inferential strategies. (shrink)

According to Moore, his argument meets three conditions for being a proof: first, the premiss is different from the conclusion; second, he knows the premiss to be the case; and, third, the conclusion follows deductively.2 Further conditions may be required, but he evidently thinks his proof would satisfy these as well. As Moore is well aware, many philosophers will feel he has not given “...any satisfactory proof of the point in question."3 Some, he believes, will want the premiss itself proved. (...) But he has.. (shrink)

A main epistemic problematic, found already in Aristotle’s Posterior Analytics, presents a threefold choice on how a belief may be justified: either through infinitely regressive reasoning, or through circular reasoning, or through reasoning resting ultimately on some foundation. Aristotle himself apparently takes the foundationalist option when he argues that rational intuition is a foundational source of scientific knowledge. The five modes of Agrippa, which pertain to knowledge generally, again pose the same problematic, the “Pyrrhonian” problematic. And here Galen and the (...) Stoics also opt for foundations. Sections I and II below explore that foundationalist option. Section III draws some lessons. And Section IV uses these to interpret Descartes. I argue that Descartes shows us the way beyond the Pyrrhonian problematic, although his way is not that traditionally attributed to him. On these basic issues of epistemology, Descartes is no Cartesian. (shrink)