Skepticism is a philosophical attitude of doubting all claims to knowledge, chiefly on the ground that the adequacy of any proposed criterion is itself questionable. Examples of thoroughgoing skeptics, wary of dogmatism in whatever guise, were Pyrrho of Elis ("Pyrrhonism" and "skepticism" are virtual synonyms) and David Hume. Other thinkers, among them Augustine, Erasmus, Montaigne, Pascal, Bayle, and Kierkergaard, sought to defend faith and religion by directing skeptical arguments against the epistemological claims of rationalism and empiricism. Pragmatism and Kant's critical philosophy represent two influential attempts to resolve a skeptical dilemma.