We do not know where Sextus Empiricus lived, but he did write in Greek and lived around the year 200. We know next to nothing about his life except that he was the compiler and historian of ancient Skepticism, especially the teachings of Pyrrho (c. 360–270 B.C.) and the philosophy named after him, Pyrrhonism. Whereas the Academic Skeptics (the school originally founded by Plato) followed Socrates (who asserted that he knew only one thing— that he knew nothing) in claiming certainty about their lack of knowledge, the Pyrrhonists claimed that we could not even know that we knew nothing. For Sextus, “Skepticism is an ability to place in antithesis, in any manner whatever, appearances and judgments, and thus—because equality of force in the objects and arguments opposed—to come first of all to suspension of judgment and then to mental tranquillity.”
Skeptics accept appearances, but not positive beliefs. Appearances of the way the world is are passive aspects of perceptions. One is forced, involuntarily, to see the world the way one does, but the skeptic actively refuses to draw conclusions from this regarding real existence. “While living undogmatically, we pay due respect to appearances.”
Using a device called tropes (modes of balancing arguments), Skeptics called attention to the relativity and undecidability of beliefs and explanations. For every physical or nonphysical state of affairs there were innumerable possibilities for its explanation, and there is no reason to suppose that we can know which is the correct explanation. While they conceded similarities in some appearances, they doubted whether these similarities led to essential knowledge. “It appears to us that honey is sweet. This we concede, for we experience sweetness through sensation. We doubt, however, whether it is sweet by reason of its essence, which is not a question of the appearance, but of that which is asserted of the appearance.” They pointed out that animals and humans perceived things differently and that among humans enormous differences existed in judgment, evaluation, taste, ability, and habits. “Different men take delight in different deeds” and “If fair and wise meant both the same to all, Dispute and strife would be no more.”
Different philosophies and religions offer equally dogmatic accounts of the origin of life and the nature of reality. There is relativity of knowledge and custom, so that it is impossible to decide the truth on these matters—or any matter. This inherent undecidability leads to a state of confusion. Here the Skeptics advised withholding assent or dissent regarding any opinion. The term they coined for this suspension of judgment was Epoche, a state of purposefully refusing to have an opinion on metaphysical matters. It was not that they denied the gods or the soul, but they refused to assent either to their existence or nonexistence. They espoused a deliberate agnosticism. Doubt all! Maintain an inner aphasia (silence) on metaphysical matters! Doubt, thus characterized as the purgation or laxative of the soul, cleanses the soul of the excrescences that befoul it. Ultimately, the Skeptics thought and claimed to have reached Ataraxia (tranquillity or imperturbability of soul), their version of peace of mind.