From sensation to reason.
150. The soul, having grasped single mind-pictures, retains its hold upon them by memory[43]; the frequent exercise of which keeps each picture fresh and complete[44]. As the air, when an orchestra is performing, receives the impression of many sounds at the same time, and yet retains the distinctive tone of each[45], so the soul by concurrent alterations of its texture preserves its hold on the separate pictures it has once grasped. Fresh operations of soul now supervene. First, from the comparison of many like pictures, comes ‘experience’ (ἐμπειρία, experientia)[46]; out of other comparisons, ‘similitude’ (ὁμοιότης), as ‘Socrates’ from his portrait; and ‘analogy’ (ἀναλογία, proportio), as ‘the centre of the earth’ from that of other spheres; ‘transference’ (μετάθεσις, translatio), as ‘eyes in the heart’; ‘composition’ (σύνθεσις, compositio), as ‘a Hippocentaur’; ‘opposition’ (ἐναντίωσις, transitio), as ‘death’ from life; ‘deprivation’ (κατὰ στέρησιν), as ‘a cripple[47].’ All these are based on the general principle of likeness and unlikeness, and may be summed up under the general heading of ‘reason’s work of comparison’ (collatio rationis)[48], or shortly, of reason (λόγος)[49]. Sensation shews us the present only; but reason brings the past and the future within our view, and points out to us the workings of cause and effect[50].
Perceptions and Conceptions.
151. With the mind-pictures (φαντασίαι, visa) which are derived from sensation we may now contrast the ‘notions’ (ἔννοιαι, notiones or intellegentiae) which are derived from the combination of sensation and reasoning; the former correspond generally to ‘perceptions,’ the latter to ‘conceptions’ in the language of modern philosophy[51]. But each of the Stoic terms is also used in a wider sense which includes the other. The sensory pictures are inscribed upon the mind as upon a blank sheet from birth upwards; in this sense they may well be called ‘entries on the mind’ (ἔννοια from ἐν νῷ)[52]. On the other hand the conceptions may be called ‘rational mind-pictures’[53]; quite as much as the sensory mind-pictures they need the prudent assent of the will before they become ‘comprehensions,’ when they are once more units capable of entering into further combinations and becoming part of scientific knowledge. If then for the sake of clearness we use the modern terms, we may say that perceptions correspond generally to individual objects which have a real existence, whilst conceptions correspond to classes of things, which (according to the Stoics) have no real existence in themselves, but only a sort of existence in our minds. Thus the ‘ideas’ of Plato are all conceptions, subjectively but not objectively existent[54]. So far as our study has gone, all conceptions are based on perceptions: therefore all the elements of knowledge either come from sense and experience solely, or from sense and experience combined with reasoning[55]; and the most important reasoning process is that comparison of like perceptions which in this philosophy takes the place of induction[56].
Preconceptions.
152. But even if all ‘conceptions’ are ultimately derived from ‘perceptions,’ it does not follow that in each particular case the mind commences de novo to collect and shape its material. On the contrary, it is clear that not only all practical life, but also all philosophy, takes for granted a great many matters which are either allowed by general consent, or at least assumed by the thinker; and these matters are mostly of the nature of class-conceptions. If it is stated that ‘the consul entered Rome in a chariot drawn by four horses,’ we assume that the ideas expressed by ‘consul,’ ‘chariot,’ ‘four,’ ‘horses,’ are matters of general consent, and we may go on to assume that the person of the consul and the locality called ‘Rome’ are also already known to the speaker and his hearers. The general term in the post-Aristotelian writers for such legitimate assumptions is ‘preconception’ (πρόληψις, anticipatio or praesumptio). The precise meaning of this term (of which the invention is ascribed to Epicurus[57]) appears not to be always the same. Most commonly the ‘preconception’ is a general term or conception, and therefore to the Stoics it is one variety of the ἔννοια; it is ‘a mental shaping, in accordance with man’s nature, of things general’[58]. All such preconceptions are foreshadowings of truth, especially in so far as they correspond to the common judgment of mankind[59]; and the art of life consists in correctly applying these presumptions to the particular circumstances with which each individual man has to deal[60]. If the preconceptions are rightly applied, they become clearer by use, and thus attain the rank of true knowledge by a process of development or ‘unravelling’ (enodatio)[61].
As to the nature of a preconception, there is a great difference between Epicurus and the Stoics. Epicurus identifies all the terms ‘preconception,’ ‘comprehension,’ ‘right opinion,’ ‘conception,’ and ‘general notion,’ and maintains that each of these is nothing but memory of a sensation frequently repeated[62]; the Stoics however hold that preconceptions are established by the mind[63], and (so far as they are common to all men) by the universal reason. This difference is fundamental. Epicurus, as a materialist in the modern sense, explains perception as a bodily function, and ‘conceptions’ of every kind as mere echoes of such bodily functions. The Stoics on the other hand recognise at each stage the activity of mind, and this in increasing degree as we proceed to the higher levels of thought.
Notions of inner growth.
153. We now approach the most critical point in the Stoic theory of knowledge. Is it possible for man to possess knowledge which is not derived, either directly or indirectly, through the organs of sense? Such a question cannot be answered by any appeal to single Stoic texts; it needs an appreciation of the whole philosophic outlook, and upon it depend the most vital principles of the system. Let us then first consider, on the supposition that such knowledge exists, what its nature is, what its content, and how it is attained by individual men. Knowledge cut off from the sense-organs is cut off from all human individuality; it is therefore the expression of the common reason (κοινὸς λόγος), and its parts are ‘common notions’ (κοιναὶ ἔννοιαι or προλήψεις), shared by gods and men, but by men only so far as they are partakers of the divine nature. The principal content of such knowledge is also clear; it includes the conception of what is morally good, and the beliefs that gods exist and that the world is governed by their providence[64]. Lastly, as of all general conceptions, the rudiments or rough outlines only of these beliefs are inborn in men, by virtue of their divine ancestry; whence they are called ‘innate notions’ (ἔμφυτοι ἔννοιαι, insitae notiones)[65]. These notions in their full development are not attainable by children at all, nor by men till they attain to reason, that is, till they become wise men[66].
‘Proofs’ of inborn notions.