an appellation given by Epicurus to his doctrine of logic. It was called canonicus, as consisting of a few canons or rules for directing the understanding in the pursuit and knowledge of truth. The canonicus of Epicurus is represented as a very slight and insufficient logic by several of the ancients, who put a great value on his ethics and physics. Laertius even assures us that the Epicureans rejected logic as a superfluous science; and Plutarch complains that Epicurus made an unskilful and preposterous use of syllogisms. But these censures seem too severe. Epicurus was not averse to the study of logic, but even gave better rules in this art than those philosophers who aimed at no glory but that of being thought logicians. He only seems to have rejected the dialectics of the Stoics, as full of vain subtleties and deceits, and fitted rather for parade and disputation than real use. The stress of Epicurus's canonicus consists in his doctrine of the criteria of truth. All questions in philosophy are either concerning words or things: concerning things, we seek their truth; concerning words, their signification: things are either natural or moral; and the former are either perceived by sense or by the understanding. Hence, according to Epicurus, arise three criteria of truth, namely, sense, anticipation or pronotion, and passion. The great canon or principle of Epicurus's logic is, that the senses are never deceived; and therefore, that every sensation or perception of an appearance is true.