1. Epicurus, the founder of the Epicurean school, was born at Gargettus, near Athens, in the year B.C. 341. He passed his youth at Samos, whither an Athenian colony had been sent, to which his father, a schoolmaster, was attached. Epicurus is said to have turned his attention to philosophy at the age of fourteen. The story goes that he gave himself to this study on finding that the teacher who was instructing him in grammar and literature, not being able to give him a satisfactory account of the Chaos of Hesiod, referred him to philosophy for an explanation. He began his new studies with the works of Democritus, and these works made such an impression on him that be never afterwards abandoned the principles of the system of Democritus. Nausiphanes, a philosopher of Democritus' school, whose lectures he attended, may also have helped to this result. At the age of thirty-two he appeared as a teacher of philosophy in Mitylene. Thence he passed to Lampsacus, and finally to Athens, where he founded in a garden (whence his pupils were called hoi apo tôn kêtôn) the school over which he presided till his death (B.C. 270). His doctrines may be broadly described as a modified form of the Hedonism of Aristippus, combined with the Atomistic theory of Democritus.
2. In the school of Epicurus a cheerful, social tone prevailed. He reduced the fundamental principles of his philosophy to short formulae (kuriai doxai) which he gave to his pupils to learn by heart. In the composition of his exceedingly numerous works he showed great carelessness, thus proving in practice the truth of his own maxim: "It costs no trouble to write." The one merit allowed his writings is, that they are easily understood; in other respects their form is generally condemned -- notably by Cicero (De Nat. Deo., I. 26). He is said to have composed, in all, 300 volumes. Diogenes Laertius gives a list of his works (X. 27.) Of these a few fragments, collected by Orelli (Leipzig, 1868) remain.
3. Epicurus defines philosophy, considered from its practical side, as "the art of securing a happy life." It follows that philosophy, considered in its theoretical aspect, must also be directed to this end. The scope of theoretical philosophy is to procure that understanding of things which will enable man to secure for himself a happy life. Epicurus divides philosophy into Canonic (Logic), Physics, and Ethics. Canonic is subservient to Physics, and Physics to Ethics. We shall treat the philosophy of Epicurus in the order indicated in this division.
§ 44.
1. Canonic lays down the laws (canons) according to which knowledge is acquired, and assigns the criteria of truth. This science, then, holds in the Epicurean system the place assigned in other philosophies to Logic and the Theory of Knowledge. Epicurus rejected Dialectic in the strict sense. His Canonic, too, is restricted to a very few principles, which he holds to be enough for the attainment of truth.
2. In his theory of human cognition, Epicurus is thoroughly sensualistic. Sensuous perception is produced by certain material images (eidôla) detached from corporeal objects (aporroai), and penetrating the channels of the senses. These images are detached from the outer surfaces of bodies, and make their way through the intervening air to our eye; they pass in through the eye, and so occasion Perception (aisthêsis).
3. But it is not Perception alone which depends on these material images; they, furthermore, give rise to Thought in the understanding. These images penetrate through the senses to the understanding, and excite in it the thought corresponding to their nature. Not only are our perceptions effected by means of these images, it is by them also that we think (Cic. De Fin., I. 6.) What we call our faculty of thought is passively recipient of these images, quite as much as our faculty of perception. This theory, it will be observed, is wholly sensualistic.
4. Out of the individual perceptions there arises gradually in the understanding a persistent universal thought-image, due to our memory of several similar perceptions of external things. It comes into consciousness at the mention of the word by which the object in question is designated. These universal thought-images (or, better, representative images) are the so-called prolêpseis. The prolêpsis, in the Epicurean theory, is no more than that one common image, under which the imagination subsumes a number of similar perceptions. This notion is in keeping with the general sensualistic character of the Epicurean teaching.
5. The aisthêsis and prolêpsis form the basis of the hupolêpsis or Judgment. In a judgment something is always assumed; a judgment, therefore, always expresses an opinion (doxa), hence the hupolêpsis and doxa are identical with one another. But an opinion of this kind may be either true or false. The question then arises: What is the criterion by which we distinguish the true from the false?
6. Epicurus holds that the criterion of first importance is the aisthêsis or immediate perception. Perception, as such, is always true. There is nothing which can disprove a perception. For neither other perceptions, nor reason, which has its rise in perception, have any higher authority. It follows that the only opinion to be esteemed true, is that opinion which is corroborated by the testimony of the senses, or at least not disproved by them, and that those opinions are to be held false, against which the senses give testimony. Second in order, as a criterion of truth, is the prolêpsis. This is to be regarded as a criterion of truth, for the reason that it is a product of sensuous perception. What has a common image of this kind as evidence in its favour is true. What has evidence of this kind against it is false, In the category of criteria we must also include the feelings (pathê). The feelings of pleasure and of pain are the criteria of practical action, i.e., they indicate what is to be sought and what to be avoided.
7. It may be objected that all perceptions are not true; for instance, a tower in the distance appears to us round and small, while, in reality, it is angular and large. To this Epicurus replies, that in our perceptions we, strictly speaking, perceive not the objects themselves, but the material images that are detached from them. An image of this sort, in its passage through the air, may lose its first outlines and dimensions, and this actually takes place in the case of the tower referred to. As it penetrates our senses in this altered form, our perception exactly corresponds to the image, and is therefore true. The false opinion arises from the circumstance that we do not restrict our judgment to the image, but extend it to the object.
8. Epicurus dispenses himself from stating any theory regarding Judgment and Inference; he considers that artificial definitions, divisions, and syllogisms cannot take the place of perceptions.