 He begins by listing preliminary arguments both for and against the possibility of knowledge. On the skeptic’s side, Henry discusses cases of sensory relativism (what seems sweet to one person does not seem sweet to another, e.g.); the changeable nature of the sensory world; and the Learner’s Paradox from the Meno. Among the anti-skeptical arguments is Aristotle’s view (Metaphysics IV) that in denying knowledge, one is thereby claiming certainty that one does not know, and thus the skeptic must admit to knowing something. He also pulls from Augustine’s oft-repeated claim that in doubting, one knows that one doubts (De vera religione xxxix.73).