The term “Stoicism” derives from the Greek word “stoa,” referring to a colonnade, such as those built outside or inside temples, around dwelling-houses, gymnasia, and market-places. They were also set up separately as ornaments of the streets and open places. The simplest form is that of a roofed colonnade, with a wall on one side, which was often decorated with paintings. Thus in the market-place at Athens the stoa poikile (Painted Colonnade) was decorated with Polygnotus’s representations of the destruction of Troy, the fight of the Athenians with the Amazons, and the battles of Marathon and Oenoe. Zeno of Citium taught in the stoa poikile in Athens, and his adherents accordingly obtained the name of Stoics. Zeno was followed by Cleanthes, and then by Chrysippus, as leaders of the school. The school attracted many adherents, and flourished for centuries, not only in Greece, but later in Rome, where the most thoughtful writers, such as Marcus Aurelius, Seneca, and Epictetus, counted themselves among its followers.
We know little for certain as to what share particular Stoics, Zeno, Cleanthes, or Chrysippus, had in the formation of the doctrines of the school, but after Chryssipus the main lines of the doctrine were complete. The Stoic doctrine is divided into three parts: logic, physics, and ethics. Stoicism is essentially a system of ethics which, however, is guided by a logic as theory of method, and rests upon physics as foundation. Briefly, their notion of morality is stern, involving a life in accordance with nature and controlled by virtue. It is an ascetic system, teaching perfect indifference (apathea) to everything external, for nothing external could be either good or evil. Hence to the Stoics both pain and pleasure, poverty and riches, sickness and health, were supposed to be equally unimportant."
2. Stoic Logic
Stoic logic is, in all essentials, the logic of Aristotle. To this, however, they added a theory, peculiar to themselves, of the origin of knowledge and the criterion of truth. All knowledge, they said, enters the mind through the senses. The mind is a blank slate, upon which sense-impressions are inscribed. It may have a certain activity of its own, but this activity is confined exclusively to materials supplied by the physical organs of sense. This theory stands, of course, in sheer opposition to the idealism of Plato, for whom the mind alone was the source of knowledge, the senses being the sources of all illusion and error. The Stoics denied the metaphysical reality of concepts. Concepts are merely ideas in the mind, abstracted from particulars, and have no reality outside consciousness.
Since all knowledge is a knowledge of sense-objects, truth is simply the correspondence of our impressions to things. How are we to know whether our ideas are correct copies of things? How do we distinguish between reality and imagination, dreams, or illusions? What is the criterion of truth? It cannot lie in concepts, since they are of our own making. Nothing is true save sense impressions, and therefore the criterion of truth must lie in sensation itself. It cannot be in thought, but must be in feeling. Real objects, said the Stoics, produce in us an intense feeling, or conviction, of their reality. The strength and vividness of the image distinguish these real perceptions from a dream or fancy. Hence the sole criterion of truth is this striking conviction, whereby the real forces itself upon our consciousness, and will not be denied. There is, thus, no universally grounded criterion of truth. It is based, not on reason, but on feeling."
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@Encyclopedia of Philosphy
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