Arcesilaus was the sixth head of Plato's academy, who turned the academy in a sceptical direction. After Plato's death, the headship of the academy passed to a series of men who developed metaphysical and ethical systems inspired by the positive arguments contained in dialogues such as the Republic and the Phaedo. Arcesilaus, however, turned away from such system-building and instead spent his energies in attacking the arguments of others. According to Cicero, the aim of such attacks was to produce epoché, or suspension of judgment.Epoché (ἐποχή) in Greek philosophy means suspension of judgment, a principle originally espoused by the non-dogmatic tradition of sceptical philosophy at the ancient Greek Academy. Sceptics adopted an attitude where, by opposing appearances (objects of sense-perception) to judgments (objects of thought), they sought a moderate approach to the problem of knowledge which would allow them to obtain a life characterized by peace of mind. Against the dogmatists, philosophers who claimed to know the truth (where even pure nihilism is a dogmatic position), sceptics held all truths gingerly. They believed the problem of knowledge to be insoluble. Therefore, they changed every truth into a proposition or hypothesis. They arrived at this attitude by contemplating antitheses. Given a proposition, they would oppose an equal proposition. The resulting collision would serve to banish dogmatism and cultivate doubt. As Sextus Empiricus wrote: "The main basic principle of the Skeptic system is that of opposing to every proposition an equal proposition; for we believe that as a consequence of this we end by ceasing to dogmatize."
Now the moment of opposition, the moment that, when controversy arises, all actions are suspended for the sake of contemplation, that moment they called epoché. In that moment, an attitude of noninvolvement should be adopted. There is suspension. Within the epoché, the skeptic avoids affirming or denying the truth of any statements about the actual nature of things. The epoché highlights the difficulty of passing judgment on the sense-impressions and ascertaining which of them are true and which false. One may be able to say what something appears to be, but cannot make any judgments about what actually is the case. In this sense, the epoché is a realization of existential freedom.
Freedom, then, is a healthy scepticism against every demand made upon personal judgment by the sensate world of appearances. Sceptics considered the hesitation arising as a result of the epoché an enlightened state of being-in-the-world. By abandoning the desire of a self with selfish actions and motivations, paradoxically, one gains everything one thought was given up by abandoning the nurture of the self (i.e. love, money, happiness) in the pursuit of mere-appearances. (In this sense, the epoche is the realization of what modern existentialism would call the "being-in-the-world.") That is why the sceptics considered the epoché to be the proper state from which to judge the relationship between appearances in order to gain peace of mind for daily living. Indeed, the scepticism that comes upon the heels of the epoché, explained Sextus, is not to shrug one's shoulders in indecision regarding competing claims. To understand suspension this way is to see skepticism as a wholly negative position. There is an essentially constructive character of sceptical argument which requires a subtler understanding of suspension. To suspend judgment in this sense is to refuse to assent to a position, while refusing to assert its negation, since either assertion would commit one to a false or misleading metaphysical presupposition. To suspend judgment is to refuse to enter into misguided discourse.
To refuse judgment is also to be free of illness. Sextus regarded scepticism not as a nihilistic attack on our cognitive life, but rather--he used a variety of medical metaphors--a form of philosophical therapy to cure us of the cognitive and emotional ills born of extreme metaphysical, moral, or epistemological positions. The sceptic wishes, from considerations of humanity, to do all he can with the arguments at his disposal to cure the self-conceit and rashness of the dogmatists. And so, just as healers of bodily ailments keep remedies of various potency, and administer the powerful ones to those whose ailments are violent and the lighter ones to those with light complaints, in the same manner the sceptic, too, propounds arguments capable of forcibly removing the condition of dogmatist self-conceit. Quoting Ludwig Wittgenstein: "The philosopher's treatment of a question is like the treatment of an illness" (Philosophical Investigations 255). Summed up by Sextus Empiricus:
Those who say that "the Sceptics abolish appearances," or phenomena, seem to me to be unacquainted with the statements of our School. For, as we said above, we do not overthrow the affective sense-impressions which induce our assent involuntarily; and these impressions are "the appearances." And when we question whether the underlying object is such as it appears, we grant the fact that it appears, and our doubt does not concern the appearance itself but the account given of the appearance,---and that is a different thing from questioning the appearance itself. For example, honey appears to us to be sweet (and this we grant, for we perceive sweetness through the senses), but whether it is also sweet in its essence is for us a matter of doubt, since this is not an appearance but a judgment regarding the appearance. And even if we do actually argue against the appearances, we do not propound such arguments with the intention of abolishing appearances, but by way of pointing out the rashness of the Dogmatists; for if reason is such a trickster as to all but snatch away the appearances from under our very eyes, surely we should view it with suspicion in the case of things non-evident so as not to display rashness by following it. (Outlines of Pyrrhoism Bk. 1: "Do the skeptics abolish appearances?")