PRELIMINARIES

Some time early in the first century, Philo and Antiochus, the two leading philosophers of the Athenian Academy, had a serious philosophical falling out. Philo advocated an externalist epistemology, holding that it was reasonable to suppose that things could be known, even though they could not, individually, be known to be known; Antiochus responded that the only way one could know that one knew anything was by knowing of some particular thing that one knew it; and thus (according to Cicero: Acad. 2.44, 111) strayed perilously close to Stoic dogmatism. Neither option appealed to their colleague Aenesidemus:

Our knowledge of Aenesidemus is sadly restricted. For his views, we are indebted principally to a précis of his Pyrrhonian Discourses from Photius of Byzantium’s library catalogue (from which 1 above is excerpted). As for direct references, Sextus refers to him by name some fifteen times (but some of these are problematic: see below, section IV), Diogenes a few times more; and that’s about it.

The Pyrrhonian Modes are argument schemata for general use against dogmatism. We have records of two main lists of Modes, the Ten and the Five, which were used at various times in the history of ancient scepticism, either independently or in some sort of systematic connection. These Modes use strategies with ancient roots in such thinkers as Protagoras, Democritus, Plato, and Aristotle, but users of the Modes were not committed to positions held by those thinkers. They were compiled long after Pyrrho (the Ten probably by Aenesidemus and the Five by a shadowy figure named Agrippa) during the first phase of the Pyrrhonian revival. In addition, we have a list of eight causal Modes attributed to Aenesidemus.

The second and final phase of Pyrrhonism occupies most of the works of Sextus Empiricus (apart from Against the Ethicists, M 11). Although he has different strategies from Aenesidemus, he lays out the Ten Modes in some detail and makes extensive use of the Five. His account of the Ten is sometimes at odds with his general practice, and this is most likely due to his use of sources from the first phase of the revival.

Besides Sextus (PH 1.36–163), we have two main sources for the Ten Modes: Diogenes Laertius (9.78–88) and Philo of Alexandria (On Drunkenness 169–202), both of whom seem to have a source independent of Sextus. Diogenes is just reporting what he knows, whereas Philo appropriates eight of the Modes for his own purpose and leaves out the other two (the Third and Ninth in the list according to Sextus). Brief mentions by Aristocles and Herrenius do not add to our understanding.

Pyrrho’s (365/60-275/70 BC) name has carried great weight in the history of philosophy ever since it was attached to one of the two main branches of ancient scepticism. Traditionally, Pyrrho’s own philosophy has been interpreted as the early version of the more sophisticated philosophy recorded by Aenesidemus and preserved in the writings of Sextus Empiricus. This traditional view is not, however, unchallenged, and in recent years alternative interpretations have been offered that suggest a dogmatic Pyrrho, whose position would be incompatible with that of later Pyrrhonian sceptics, although having enough in common with it to serve as its distant historical source.

To what extent is the appropriation of Pyrrho by the later sceptics legitimate? It is important for an appraisal of Pyrrho’s place in the history of scepticism to ascertain which insights, if any, were common to Pyrrho and the later Pyrrhonists. But the contours of Pyrrho’s philosophy are blurred; the evidence is scant and subject to conflicting interpretations. Perhaps the situation was not a great deal better in the first century BC, when Aenesidemus introduced Pyrrhonism as radical scepticism, as opposed to the mitigated scepticism of the Academy, or in the late second century AD, when Sextus was at work. Their references to Pyrrho are cautious and hardly exegetical. Later accounts often emphasise his admirable state of mind, variously called indifference (adiaphoria), impassivity (apatheia), and tranquility (ataraxia). Sextus claims to call his scepticism “Pyrrhonian” “from the fact that Pyrrho appears to us to have attached himself to scepticism more vigorously and conspicuously than anyone before him” (PH 1.7).

Sextus Empiricus, the best known to us of the Pyrrhonian sceptics and the only one whose works have survived substantially intact, was, as his name indicates, a member of the Empirical school of medicine. Other evidence also points to a close and long-sustained relation between medical Empiricism and Pyrrhonian scepticism. Diogenes Laertius' list of Pyrrhonists includes at least three Empiricists apart from Sextus himself: Menodotus, Theodas, and Sextus' student, Saturninus (9.115-16). Some of the others may also have been Empiricists, and there are figures not included on DL’s list who seem to have been members of both schools.

In his Outline of Empiricism (Subfiguratio empirica), where he adopts the point of view of an Empiricist (Deichgräber [20[ 43, 20- 22), Galen maintains that the Empiricist is to medicine as the Pyrrhonist is to the whole of life (82, 28 et seq.), and he criticizes Menodotus harshly for failing to live up to the ideal represented by Pyrrho, whom he (Menodotus himself) had held up to his fellow Empiricists as a model (84, 13 et seq.). Sextus mentions empirical forms of the arts with approval: grammar (M 1.49-53, 61); astronomy, navigation, and farming (M 5.1-2). He wrote a work on Empirical medicine (M 1.61), which is not extant, and his surviving works contain many expressions of sympathy for the Empiricists and their ideas (PH 2.246, 254; M 5.104; M 8.191, 288, 291).

When I first wrote a paper about the difference between Academic and Pyrrhonist Sceptics a long time ago, I was less interested in the differences than in the commonalities. My point was to get away from the Humean distinction between moderate Academics and radical Pyrrhonists. I argued that both were radicals - not, as they came to be seen in early modern times, dogmatists who denied the possibility of knowledge more or less generally, but in the ancient sense of having no philosophical doctrines. They used the same method of arguing for and against any given thesis or belief, declaring the debate undecided, and suspending judgement. The “mitigated” sceptic, who believes that nothing can be known though one may have more or less well-founded opinions, was a figure invented by Carneades in order to refute the dogmatists' objection that suspension of judgement on all matters will make life impossible. Ironically, this figure later became the model of modern versions of scepticism.

Up to this point I still think I was right - at least as far as the early sceptical Academics Arcesilaus and Carneades were concerned. Arcesilaus argued that, given their conception of knowledge and wisdom, the Stoics themselves ought to suspend judgement on all matters. Carneades offered an alternative epistemology to counterbalance the impressive Stoic theory. But these philosophers did not maintain that they were right and the Stoics wrong, or that one should accept their own proposal. The only salient difference that seemed to me to be left between those Academics and their Pyrrhonist successors was the curious claim of the Pyrrhonists that their so-called “way of life” would lead to the goal that other Hellenistic schools were also endorsing – tranquility.

If the sceptic holds nothing to be true, his dogmatic opponent argues, he is not able to act. This is the core of the famous Apraxia challenge, arguably the best known anti-sceptical argument in antiquity. Several versions of this argument figure in ancient scepticism. At least for the most part, these arguments rely on core assumptions of Stoic epistemology and theory of action: that we have impressions (phantasiai), some of which are practical, i.e. prescribe an action as to be done, and that we either assent to our impressions or not. In assenting to an impression, we hold something to be true. For fools (i.e. almost everyone), this amounts to having an opinion. For the wise person, every instance of holding something to be true is a piece of knowledge. In the case of practical impressions, assent (sunkatathesis) is further identified with impulse (hormê). If there are no external impediments, impulse sets off action.

The sceptic’s explanation of his actions most importantly consists in his response to the Apraxia challenge, and more particularly, in his critical engagement with the Stoic claim that, in action, we assent and thus hold something to be true. Our interpretation of his response to the Apraxia challenge, however, relates to a broader framework of questions. First, how closely does the sceptic’s life resemble ordinary life? Are the sceptic’s actions, in the end, like everybody’s actions? Secondly, does the sceptic consider his way of life as an attempt at living well? Is suspension of judgement, perhaps, a safer road to happiness than adherence to a (potentially false) philosophical account of what is good and bad?