The parallel between Aenesidêmus and Protagoras would become still more complete were it true that the Alexandrian philosopher also sought to base his Scepticism on the Heracleitean theory of Nature, arguing that contradictory assertions are necessitated by the presence of contradictory properties in every object.
That Aenesidêmus held this view is stated as a fact by Sextus, whose testimony is here corroborated by Tertullian, or rather by Tertullian’s informant, Soranus. We find, however, that Zeller, who formerly accepted the statement in question as true, has latterly seen reason to reject it. Aenesidêmus cannot, he thinks, have been guilty of so great an inconsistency as to base his Scepticism on the dogmatic physics of Heracleitus. And he explains the agreement of the ancient authorities by supposing that the original work of Aenesidêmus contained a critical account of the Heracleitean theory, that this was misinterpreted into an expression of his adhesion to it by Soranus, and that the blunder was adopted at second-hand by both Sextus and Tertullian.[299]
It is, at any rate, certain that the successors of Aenesidêmus adhered to the standpoint of Pyrrho. One of them, Agrippa, both simplified and strengthened the arguments of the school by reducing the ten Tropes to five. The earlier objections to human certainty were summed up under two heads: the irreconcilable conflict of opinions on all subjects; and the essential relativity of consciousness, in which the percipient and the perceived are so intimately united that what things in themselves are cannot possibly be discovered. The other three Tropes relate to the baselessness of reasoning. They were evidently suggested by Aristotle’s remarks on the subject. The process of proof cannot be carried backwards ad infinitum, nor can it legitimately revolve in a circle. Thus much had already been admitted, or rather insisted on by the great founder of logic. But the Sceptics could not agree to Aristotle’s contention, that demonstration may be based on first principles of self-evident certainty. They here fell back on their main argument; that the absence of general agreement on every point is fatal to the existence of such pretended axioms. A still further simplification was effected by the reduction of the five Tropes to two—that all reasoning rests on intuition, and that men’s intuitions are irreconcilably at variance with one another.[300] As against true science, the sceptical Tropes are powerless, for the validity of its principles has nothing to do with their general acceptance. They are laid before the learner for his instruction, and if he chooses to regard them as either false or doubtful, the misfortune will be his and not theirs. But as against all attempts to constrain belief by an appeal to authority, the Tropes still remain invincible. Whether the testimony invoked be that of ancient traditions or of a supposed inward witness, there is always the same fatal objection that other traditions and other inward witnesses tell quite a different story. The task of deciding between them must, after all, be handed over to an impersonal reason. In other words, each individual must judge for himself and at his own risk, just as he does in questions of physical science.
We have already observed that Scepticism among the ancients was often cultivated in connexion with some positive doctrine which it indirectly served to recommend. In the case of its last supporters, this was the study of medicine on an empirical as opposed to a deductive method. The Sceptical contention is that we cannot go beyond appearances; the empirical contention is, that all knowledge comes to us from experience, and that this only shows us how phenomena are related to one another, not how they are related to their underlying causes, whether efficient or final. These allied points of view have been brought into still more intimate association by modern thought, which, as will be shown in the concluding chapter, has sprung from a modified form of the ancient Scepticism, powerfully aided by a simultaneous development of physical science. At the same time, the new school have succeeded in shaking off the narrowness and timidity of their predecessors, who were still so far under the influence of the old dogmatists as to believe that there was an inherent opposition between observation and reasoning in the methods of discovery, between facts and explanations in the truths of science, and between antecedence and causation in the realities of Nature. In this respect, astronomy has done more for the right adjustment of our conceptions than any other branch of knowledge; and it is remarkable that Sextus Empiricus, the last eminent representative of ancient Scepticism, and the only one (unless Cicero is to be called a Sceptic) whose writings are still extant, should expressly except astronomy from the destructive criticism to which he subjects the whole range of studies included in what we should call the university curriculum of his time.[301] We need not enter into an analysis of the ponderous compilation referred to; for nearly every point of interest which it comprises has already been touched on in the course of our investigation; and Sextus differs only from his predecessors by adding the arguments of the New Academy to those of Protagoras and Pyrrho, thus completing the Sceptical cycle. It will be enough to notice the singular circumstance that so copious and careful an enumeration of the grounds which it was possible to urge against dogmatism—including, as we have seen, many still employed for the same or other purposes,—should have omitted the two most powerful solvents of any. These were left for the exquisite critical acumen of Hume to discover. They relate to the conception of causation, and to the conception of our own personality as an indivisible, continuously existing substance, being attempts to show that both involve assumptions of an illegitimate character. Sextus comes up to the very verge of Hume’s objection to the former when he observes that causation implies relation, which can only exist in thought;[302] but he does not ask how we come to think such a relation, still less does he connect it with the perception of phenomenal antecedence; and his attacks on the various mental faculties assumed by psychologists pass over the fundamental postulate of personal identity, thus leaving Descartes what seemed a safe foundation whereon to rebuild the edifice of metaphysical philosophy.
XI.
The effect aimed at by ancient Scepticism under its last form was to throw back reflection on its original starting-point. Life was once more handed over to the guidance of sense, appetite, custom, and art.[303] We may call this residuum the philosophy of the dinner-bell. That institution implies the feeling of hunger, the directing sensation of sound, the habit of eating together at a fixed time, and the art of determining time by observing the celestial revolutions. Even so limited a view contains indefinite possibilities of expansion. It involves the three fundamental relations that other philosophies have for their object to work out with greater distinctness and in fuller detail: the relation between feeling and action, binding together past, present, and future in the consciousness of personal identity; the relation of ourselves to a collective society of similarly constituted beings, our intercourse with whom is subject from the very first to laws of morality and of logic; and, finally, the relation in which we stand, both singly and combined, to that universal order by which all alike are enveloped and borne along, with its suggestions of a still larger logic and an auguster morality springing from the essential dependence of our individual and social selves on an even deeper identity than that which they immediately reveal. We have already had occasion to observe how the noble teaching of Plato and the Stoics resumes itself in a confession of this threefold synthesis; and we now see how, putting them at their very lowest, nothing less than this will content the claims of thought. Thus, in less time than it took Berkeley to pass from tar-water to the Trinity, we have led our Sceptics from their philosophy of the dinner-bell to a philosophy which the Catholic symbols, with their mythologising tendencies, can but imperfectly represent. And to carry them with us thus far, nothing more than one of their own favourite methods is needed. Wherever they attempt to arrest the progress of enquiry and generalisation, we can show them that no real line of demarcation exists. Let them once admit the idea of a relation connecting the elements of consciousness, and it will carry them over every limit except that which is reached when the universe becomes conscious of itself. Let them deny the idea of a relation, and we may safely leave them to the endless task of analysing consciousness into elements which are feelings and nothing more. The magician in the story got rid of a too importunate familiar by setting him to spin ropes of sand. The spirit of Scepticism is exorcised by setting it to divide the strands of reason into breadthless lines and unextended points.
What influence Scepticism exercised on the subsequent course of Greek thought is difficult to determine. If we are to believe Diogenes Laertius, who flourished in the second quarter of the third century A.D., every school except Epicureanism had at that time sunk into utter neglect;[304] and it is natural to connect this catastrophe with the activity of the Sceptics, and especially of Sextus Empiricus, whose critical compilation had appeared not long before. Such a conclusion would be supported by the circumstance that Lucian, writing more than fifty years earlier, directs his attacks on contemporary philosophy chiefly from the Sceptical standpoint; his Hermotimus in particular being a popularised version of the chief difficulties raised from that quarter. Still it remains to be shown why the criticism of the Greek Humanists, of Pyrrho, and of the New Academy should have produced so much more powerful an effect under their revived form than when they were first promulgated; and it may be asked whether the decline of philosophy should not rather be attributed to the general barbarisation of the Roman empire at that period.
We have also to consider in what relation the new Scepticism stood to the new Platonism by which, in common with every other school, it was eventually either displaced or absorbed. The answer usually given to this question is that the one was a reaction from the other. It is said that philosophy, in despair of being able to discover truth by reason, took refuge in the doctrine that it could be attained by supernatural revelation; and that this doctrine is the characteristic mark distinguishing the system of Plotinus from its predecessors. That a belief in the possibility of receiving divine communications was widely diffused during the last centuries of polytheism is, no doubt, established, but that it ever formed more than an adjunct to Neo-Platonism seems questionable; and there is no evidence that we are aware of to show that it was occasioned by a reaction from Scepticism. As a defence against the arguments of Pyrrho and his successors, it would, in truth, have been quite unavailing; for whatever objections applied to men’s natural perceptions, would have applied with still greater force to the alleged supernatural revelation. Moreover, the mystical element of Neo-Platonism appears only in its consummation—in the ultimate union of the individual soul with the absolute One; the rest of the system being reasoned out in accordance with the ordinary laws of logic, and in apparent disregard of the Sceptical attacks on their validity.
The truth is that critics seem to have been misled by a superficial analogy between the spiritualistic revival accomplished by Plotinus, and the Romantic revival which marked the beginning of the present century. The two movements have, no doubt, several traits in common; but there is this great difference between them, that the latter was, what the former was not, a reaction against individualism, agnosticism, and religious unbelief. The right analogy will be found not by looking forward but by looking back. It will then be seen that the Neo-Platonists were what their traditional name implies, disciples of Plato, and not only of Plato but of Aristotle as well. They stood in the same relation to the systems which they opposed as that in which the two great founders of spiritualism had stood to the naturalistic and humanist schools of their time—of course with whatever modifications of a common standpoint were necessitated by the substitution of a declining for a progressive civilisation. Like Plato also, they were profoundly influenced by the Pythagorean philosophy, with its curious combination of mystical asceticism and mathematics. And, to complete the analogy, they too found themselves in presence of a powerful religious reaction, against the excesses of which, like him, they at first protested, although with less than his authority, and only, like him, to be at last carried away by its resistless torrent. It is to the study of this religious movement that we must now address ourselves, before entering on an examination of the latest form assumed by Greek philosophy among the Greeks themselves.
Note.—It does not enter into the plan of this work to study the educational and social aspects of Greek philosophy under the Roman Empire. Those who wish for information on the subject should consult Capes’s Stoicism, Martha’s Moralistes sous l’Empire Romain, Renan’s Marc-Aurèle, chap, iii., Aubertin’s Sénèque et Saint Paul, Havet’s Christianisme et ses Origines, Vol. II., Gaston Boissier’s Religion Romaine, Duruy’s Histoire Romaine, chap, lxi., Friedländer’s Darstellungen aus der Sittengeschichte Rom’s, Vol. III., chap. v. (5th ed.), and Bruno Bauer’s Christus und die Cäsaren.