Part 2 — CHAPTER V. LOGIC OF THE STOICS.

B. Theory of knowledge. (1) General character of this theory. The Stoic theory of knowledge turns about the enquiry for a criterion or standard by which what is true in notions may be distinguished from what is false. Since every kind of knowledge, no matter what be its object, must be tested by this standard, it follows that the standard cannot be sought in the subject-matter of notions, but, on the contrary, in their form. The enquiry after a standard becomes therefore identical with another—the enquiry as to what kind of notions supply a knowledge that may be depended upon, or what activity of the power of forming conceptions carries with it a pledge of its own truth. It is impossible to answer these questions without investigating the origin, the various kinds, and the value and importance of notions. Hence the problem proposed to the Stoics is reduced to seeking by an analysis of notions to obtain a universally valid standard by which their truth may be tested.

(2) Prominent points in the theory of knowledge. The character of this theory of knowledge appears mainly in three particulars:—(1) In the importance attached by the Stoics to the impressions of the senses. This feature they inherited from the Cynics and shared with the Epicureans. (2) In the exaltation of expression into a conception—a trait distinguishing this from either of the two other contemporary Schools. (3) In the practical turn given to the question of a criterion or standard of truth. We proceed to the expansion of this theory in detail.

(2) Its value. No very high estimate can therefore be formed of the formal logic of the Stoics. Incomplete as our knowledge of that logic may be, still what is known is enough to determine the judgment absolutely. We see indeed that the greatest care was expended by the Stoics since the time of Chrysippus in tracing the forms of intellectual procedure into their minutest ramifications, and referring them to fixed types. At the same time, we see that the real business of logic was lost sight of in the process, the business of portraying the operations of thought, and giving its laws, whilst the most useless trifling with forms was recklessly indulged in. The Stoics can have made no discoveries of importance even as to logical forms, or they would not have been passed over by writers ever on the alert to note the slightest deviation from the Aristotelian logic. Hence the whole contribution of the Stoics to the field of logic consists in their having clothed the logic of the Peripatetics with a new terminology, and having developed certain parts of it with painful minuteness, whilst they wholly neglected other parts, as was the fate of the part treating of inference. Assuredly it was no improvement for Chrysippus to regard the hypothetical rather than the categorical as the original form of inference. Making every allowance for the extension of the field of logic, in scientific precision it lost more than it gained by the labours of Chrysippus. The history of philosophy cannot pass over in silence this branch of the Stoic system, so carefully cultivated by the Stoics themselves, and so characteristic of their intellectual attitude. Yet, when all has been said, the Stoic logic is only an outpost of their system, and the care which was lavished on it since the time of Chrysippus indicates the decline of intellectual originality.