We must mention as an additional point of contrast between the Stoics and the subsequent schools which they most resembled, that while these look on the soul as inseparable from the body, and sharing its fortunes from first to last, although perfectly distinct from it in idea, they emphasised the antithesis between the two just as strongly as Plato, giving the soul an absolutely infinite power of self-assertion during our mortal life, and allowing it a continued, though not an immortal, existence after death.[31]
What has been said of the human soul applies equally to God, who is the soul of the world. He also is conceived under the form of a material but very subtle and all-penetrating element to which our souls are much more closely akin than to the coarse clay with which they are temporarily associated. And it was natural that the heavenly bodies, in whose composition the ethereal element seemed so visibly to predominate, should pass with the Stoics, as with Plato and Aristotle, for conscious beings inferior only in sacredness and majesty to the Supreme Ruler of all.[32] Thus, the philosophy which we are studying helps to prove the strength and endurance of the religious reaction to which Socrates first gave an argumentative expression, and by which he was ultimately hurried to his doom. We may even trace its increasing ascendency through the successive stages of the Naturalistic school. Prodicus simply identified the gods of polytheism with unconscious physical forces;[33] Antisthenes, while discarding local worship, believed, like Rousseau, in the existence of a single deity;[34] Zeno, or his successors, revived the whole pantheon, but associated it with a pure morality, and explained away its more offensive features by an elaborate system of allegorical interpretation.[35]
It was not, however, by its legendary beliefs that the living power of ancient religion was displayed, but by the study and practice of divination. This was to the Greeks and Romans what priestly direction is to a Catholic, or the interpretation of Scripture texts to a Protestant believer. And the Stoics, in their anxiety to uphold religion as a bulwark of morality, went entirely along with the popular superstition; while at the same time they endeavoured to reconcile it with the universality of natural law by the same clumsily rationalistic methods that have found favour with some modern scientific defenders of the miraculous. The signs by which we are enabled to predict an event entered, they said, equally with the event itself, into the order of Nature, being either connected with it by direct causation, as is the configuration of the heavenly bodies at a man’s birth with his after fortunes, or determined from the beginning of the world to precede it according to an invariable rule, as with the indications derived from inspecting the entrails of sacrificial victims. And when sceptics asked of what use was the premonitory sign when everything was predestined, they replied that our behaviour in view of the warning was predestined as well.[36]
To us the religion of the Stoics is interesting chiefly as a part of the machinery by which they attempted to make good the connexion between natural and moral law, assumed rather than proved by their Sophistic and Cynic precursors. But before proceeding to this branch of the subject we must glance at their mode of conceiving another side of the fundamental relationship between man and the universe. This is logic in its widest sense, so understood as to include the theory of the process by which we get our knowledge and of the ultimate evidence on which it rests, no less than the theory of formal ratiocination.
III.
In their theory of cognition the Stoics chiefly followed Aristotle; only with them the doctrine of empiricism is enunciated so distinctly as to be placed beyond the reach of misinterpretation. The mind is at first a tabula rasa, and all our ideas are derived exclusively from the senses.[37] But while knowledge as a whole rests on sense, the validity of each particular sense-perception must be determined by an appeal to reason, in other words, to the totality of our acquired experience.[38] So also the first principles of reasoning are not to be postulated, with Aristotle, as immediately and unconditionally certain; they are to be assumed as hypothetically true and gradually tested by the consequences deducible from them.[39] Both principles well illustrate the synthetic method of the Stoics—their habit of bringing into close connexion whatever Aristotle had studiously held apart. And we must maintain, in opposition to the German critics, that their method marks a real advance on his. It ought at any rate to find more favour with the experiential school of modern science, with those who hold that the highest mathematical and physical laws are proved, not by the impossibility of conceiving their contradictories, but by their close agreement with all the facts accessible to our observation.
It was a consequence of the principle just stated that in formal logic the Stoics should give precedence to the hypothetical over the categorical syllogism.[40] From one point of view their preference for this mode of stating an argument was an advance on the method of Aristotle, whose reasonings, if explicitly set out, would have assumed the form of disjunctive syllogisms. From another point of view it was a return to the older dialectics of Socrates and Plato, who always looked on their major premises as possessing only a conditional validity—conditional, that is to say, on the consent of their interlocutor. We have further to note that both the disjunctive and the hypothetical syllogism were first recognised as such by the Stoics; a discovery connected with the feature which most profoundly distinguishes their logic from Aristotle’s logic. We showed, in dealing with the latter, that it is based on an analysis of the concept, and that all its imperfections are due to that single circumstance. It was the Stoics who first brought judgment, so fatally neglected by the author of the Analytics, into proper prominence. Having once grasped propositions as the beginning and end of reasoning, they naturally and under the guidance of common language, passed from simple to complex assertions, and immediately detected the arguments to which these latter serve as a foundation. And if we proceed to ask why they were more interested in judgment than in conception, we shall probably find the explanation to be that their philosophy had its root in the ethical and practical interests which involve a continual process of injunction and belief, that is to say, a continual association of such disparate notions as an impression and an action; while the Aristotelian philosophy, being ultimately derived from early Greek thought, had for its leading principle the circumscription of external objects and their representation under the form of a classified series. Thus the naturalistic system, starting with the application of scientific ideas to human life, ultimately carried back into science the vital idea of Law; that is, of fixed relations subsisting between disparate phenomena. And this in turn led to the reinterpretation of knowledge as the subsumption of less general under more general relations.
Under the guidance of a somewhat similar principle the Stoic logicians attempted a reform of Aristotle’s categories. These they reduced to four: Substance, Quality, Disposition, and Relation (τὸ ὑποκείμενον, τὸ ποιὸν, τὸ πῶς ἔχον, and τὸ πρός τι πῶς ἔχον[41]); and the change was an improvement in so far as it introduced a certain method and subordination where none existed before; for each category implies, and is contained in, its predecessor; whereas the only order traceable in Aristotle’s categories refers to the comparative frequency of the questions to which they correspond.
With the idea of subsumption and subordination to law, we pass at once to the Stoic ethics. For Zeno, the end of life was self-consistency; for Cleanthes, consistency with Nature; for Chrysippus, both the one and the other.[42] The still surviving individualism of the Cynics is represented in the first of these principles; the religious inspiration of the Stoa in the second; and the comprehensiveness of its great systematising intellect in the last. On the other hand, there is a vagueness about the idea of self-consistency which seems to date from a time when Stoicism was less a new and exclusive school than an endeavour to appropriate whatever was best in the older schools. For to be consistent is the common ideal of all philosophy, and is just what distinguishes it from the uncalculating impulsiveness of ordinary life, the chance inspirations of ordinary thought. But the Peripatetic who chose knowledge as his highest good differed widely from the Hedonist who made pleasure or painlessness his end; and even if they agreed in thinking that the highest pleasure is yielded by knowledge, the Stoic himself would assert that the object of their common pursuit was with both alike essentially unmoral. He would, no doubt, maintain that the self-consistency of any theory but his own was a delusion, and that all false moralities would, if consistently acted out, inevitably land their professors in a contradiction.[43] Yet the absence of contradiction, although a valuable verification, is too negative a mark to serve for the sole test of rightness; and thus we are led on to the more specific standard of conformability to Nature, whether our own or that of the universe as a whole. Here again a difficulty presents itself. The idea of Nature had taken such a powerful hold on the Greek mind that it was employed by every school in turn—except perhaps by the extreme sceptics, still faithful to the traditions of Protagoras and Gorgias—and was confidently appealed to in support of the most divergent ethical systems. We find it occupying a prominent place both in Plato’s Laws and in Aristotle’s Politics; while the maxim, Follow Nature, was borrowed by Zeno himself from Polemo, the head of the Academy, or perhaps from Polemo’s predecessor, Xenocrates. And Epicurus, the great opponent of Stoicism, maintained, not without plausibility, that every animal is led by Nature to pursue its own pleasure in preference to any other end.[44] Thus, when Cleanthes declared that pleasure was unnatural,[45] he and the Epicureans could not have been talking about the same thing. They must have meant something different by pleasure or by nature or by both.
The last alternative seems the most probable. Nature with the Stoics was a fixed objective order whereby all things work together as co-operant parts of a single system. Each has a certain office to perform, and the perfect performance of it is the creature’s virtue, or reason, or highest good: these three expressions being always used as strictly synonymous terms. Here we have the teleology, the dialectics, and the utilitarianism of Socrates, so worked out and assimilated that they differ only as various aspects of a single truth. The three lines of Socratic teaching had also been drawn to a single point by Plato; but his idealism had necessitated the creation of a new world for their development and concentration. The idea of Nature as it had grown up under the hands of Heracleitus, the Sophists, and Antisthenes, supplied Zeno with a ready-made mould into which his reforming aspirations could be run. The true Republic was not a pattern laid up in heaven, nor was it restricted to the narrow dimensions of a single Hellenic state. It was the whole real universe, in every part of which except in the works of wicked men a divine law was recognised and obeyed.[46] Nay, according to Cleanthes, God’s law is obeyed even by the wicked, and the essence of morality consists only in its voluntary fulfilment. As others very vividly put it, we are like a dog tied under a cart; if we do not choose to run we shall be dragged along.[47]