The Greeks sometimes called skepticism, Pyrrhonism, after Pyrrho, an austere teacher of serene non-commitment. He was not a pure skeptic himself, in the epistemological sense, but his teachings led directly to what we now call skepticism.
Pyrrho was born a little over a century after Socrates. Plato was about 60, and Aristotle about 20, when Pyrrho was born, and Pyrrho lived to see both of them die. Pyrrho lived to see the rise and fall of Alexander the Great, the civil wars in his empire, and the opening of the Eastern world to the West. This meant that Pyrrho witnessed the splintering of Platonism and Aristotelianism into many bickering schools. He travelled to India with Alexander's army and witnessed the spectacle of novel Eastern customs, at once utterly different from the Greek but equally civilized and supported by a reflective philosophical tradition. He witnessed the social and political chaos, war, and strife that followed the death and succession of Alexander.
Some scholars find a political origin to Pyrrho's skepticism in this, on the theory that traumatic periods produce disillusionment and resignation, the souring and obsolescence of traditional beliefs, a tenacious relativism of beliefs, virtues, and habits that will not assign absolute superiority to any, and a need for new methods of coping in a hectic world.[Note 3]
There is probably some truth in this, and it does seem that skepticism recurs through history in the periods of greatest upheaval and dissolution. But it is unfair to skepticism to reduce it to the play of historical forces and forget that it has its immanent 'reasons' that have a claim on all of us, regardless of our circumstances. That is, philosophies have grounds, not just causes. Pyrrho's own biography, scanty as it is, gives a good idea of how these reasons operated in his life.
Pyrrho began his intellectual life as a student and disciple of the Stoics, who taught that peace of mind was the highest end of life and that a knowledge of truth was required to attain and maintain it. Pyrrho accordingly sought truth. But he heard the Stoics say one thing was true, the Pythagoreans say another, the atomists another; he heard many versions of Plato's truth and of Aristotle's. He heard disagreements among the disciples of Anaxagoras, Heraclitus, Parmenides, Empedocles, and Protagoras. For every question of interest to philosophy he heard the Stoic doctrine contradicted by dozens of other doctrines, all of which also differed among themselves. What was worse, each position had reasons and evidence to support itself and to subvert and refute its opponents. To Pyrrho it was a standoff. He gave up in despair and admitted to himself that he could not decide among them and did not know what was true.
Voila! He discovered that his confession of ignorance had given him peace of mind. He had ironically attained the goal of all Stoicism by giving up and reversing its means. He had found a tranquillity in honestly confessing his ignorance. Moreover, his tranquillity seemed as durable and serene as the Stoical peace of mind that presumed to depend on true knowledge —and that embroiled the Stoics in endless disputes and other perturbations.
Sextus Empiricus compares this irony to the case of the Greek painter, Apelles, who while painting a horse had trouble getting the foam on its mouth to look right (I.28).[Note 4] He tried all the subtleties of technique he knew but could not get the effect he wanted. Giving up in despair, he threw his sponge at the painting, and it left the perfect impression of foam.
That Pyrrho achieved his peace of mind accidentally and unexpectedly may itself be no accident. As we will see, to avoid inconsistency or rashness a skeptic may be required to claim that the connection between the confession of ignorance and peace of mind is ad hoc, adventitious, unlooked for, and a perpetual surprise. To put it more sympathetically, Nescio will never positively expect peace of mind to follow from the confession of ignorance (I.29), even if she always finds it to do so. Nesciam, however, does expect peace of mind from the attainment of ignorance, and pursues skepticism in order to achieve it (I.12, I.190, I.205, I.232). But not even Nesciam will rashly confess ignorance when knowledge may be available simply to cheat herself with a false confession and hope to find peace.
Pyrrho may have achieved piece of mind unexpectedly as a consequence of confessing his ignorance. But others saw this is as a quasi-spiritual regimen that could be imitated. Nesciam seems motivated to retrace Pyrrho's steps, which means to do so without the element of surprise or unknowing. Nescio may seek knowledge and find ignorance and peace of mind by the irony of failure; but Nesciam seeks peace of mind through attainment of ignorance; this makes the avoidance of dogmatism a program, not a failure on the path to knowledge.
Pyrrho realized that the ignorance he confessed to himself was very different in kind from the ignorance of children, dogs, and stones. It was learned ignorance. It was the result of intellect and inquiry, of mind trying to know and failing, of reason propounding questions to itself that it could not answer. It was a painfully acquired recognition of his limitations and himself, not the barren ignorance that never tried to conquer itself. Ever since Socrates learned that all his wisdom consisted in knowing his ignorance,[Note 5] skeptics have prized learned ignorance as the first step in honest inquiries toward truth.
Learned ignorance is not an end in itself. However, in the skeptic's experience inquiry usually fails and when it fails honest inquirers recognize learned ignorance to be the result. But before any serious inquiry can begin we must admit that we do not know. Learned ignorance is humility and honesty, the opposite of rash prejudice, and at least the ground (if not the consequence) of any genuine investigation.
Pyrrho, or his students, realized that the peace of mind he attained was made possible only by the search for truth (I.205). This might have been why they continued to search for truth themselves. For it was open to them to quit the search for truth once they attained their ataraxia or peace of mind. But no skeptic did this. Another reason may have been that their tranquillity in learned ignorance might appear, or actually be, dishonest if it were not continually challenged and nourished by the search for truth. It is also possible that Pyrrho and other skeptics hoped, or conceded as a possibility, that a better peace of mind could be attained through true knowledge than through learned ignorance. In any case classical skepticism had two goals: truth and peace of mind. We might say that true knowledge was the theoretical end of skepticism, and peace of mind the practical end, although the skeptics themselves never made this distinction.
Sextus occasionally writes as if the practical end were primary for many Pyrrhoneans, as it was for Pyrrho himself (I.12, I.25, I.215). Even within the theoretical or epistemological pursuit, similarly, some Pyrrhoneans preferred failure (continued skepticism) to success (dogmatism) in their inquiries, at least when peace of mind followed the confession of ignorance (I.30, I.100, I.204). Others admitted their willingness to assent to a good argument when they saw one (II.251). Nescio is of the latter type, and prefers truth to peace of mind. Nesciam is of the former type, and prefers ataraxia to truth, and believes that ignorance or non-assertion leads to ataraxia.
In a passage that is ironic but not insincere, Sextus says there is a third end of skepticism: to cure dogmatists of their rashness and self-conceit (III.280-281). Skeptics seek this end because the skeptic is "a lover of his kind" (III.280).[Note 6]
Modern skeptics drop the goal of peace of mind and pursue truth unremittingly. They become skeptics through a sense of epistemic duty and follow inquiry wherever it may lead emotionally. They typically achieve despair, not tranquillity. Some of the reasons for this result will be explored.
and on wikipedia:
If ever one is in a position in which they are unable to refute a theory, Pyrrhonists reply "Just as, before the birth of the founder of the School to which you belong, the theory it holds was not as yet apparent as a sound theory, although it was really in existence, so likewise it is possible that the opposite theory to that which you now propound is already really existent, though not yet apparent to us, so that we ought not as yet to yield assent to this theory which at the moment seems to be valid.
