159. From a very early period, as we have already indicated, Stoic teachers accepted probability as the guide of life in its details, being perhaps aided by the happy ambiguity of the expression ‘reasonableness’ (τὸ εὔλογον), which suggests formally the pursuit of reason, but in practice is a justification of every course of which a plausible defence can be brought forward. Ptolemy Philopator, we are told, jestingly put wax fruit before Sphaerus at his table, and when Sphaerus tried to eat it cried out that he was giving his assent to a false mind-picture. Sphaerus replied that he had not assented to the picture ‘this is fruit,’ but only to the picture ‘this is probably fruit[92].’ Antipater of Tarsus, when he explained that the very essence of virtue lay in the choice of natural ends upon probable grounds[93], was felt to be giving way to Carneades[94]. Panaetius justified the maintaining of that which is plausible by the advocate, and Cicero, whose own conscience was not at ease in the matter, was glad enough to quote so respectable an authority on his own behalf[95]. In the Roman imperial period a growing spirit of humility and pessimism led to a general disparagement of human knowledge, centring in attacks on the trustworthiness of the senses. So Seneca speaks of the ‘usual weakness’ of the sense of sight[96], and Marcus Aurelius feels that ‘the organs of sense are dim and easily imposed upon[97].’ The older Stoics had admitted the frequent errors of the senses[98], but they had been confident they could surmount this difficulty. Their latest disciples had lost the courage to do this, and in consequence the practice of ‘suspension of judgment,’ which before had been the exception[99], became with them the rule. Nevertheless Epictetus, who alone amongst these later Stoics was an ardent student of dialectics, held fast to the main principle that certainty is attainable. ‘How indeed’ he said ‘perception is effected, whether through the whole body or any part, perhaps I cannot explain, for both opinions perplex me. But that you and I are not the same, I know with perfect certainty[100].’

Grammar.

160. Having now dealt with the theory of knowledge, we may consider briefly the subordinate sciences (or rather ‘arts’) of Grammar, Logic (in the narrower sense), and Style. Here we may leave the technical divisions and subdivisions of the Stoics; for these matters are substantially independent of the main lines upon which the ancient philosophies parted company, and have for us only a secondary and historical interest. The Stoics distinguish five parts of speech: ‘name’ (ὄνομα, nomen), as ‘Diogenes’; ‘class-name’ (προσηγορία, appellatio), as ‘man, horse’[101]; ‘verb’ (ῥῆμα, verbum); ‘conjunction’ (σύνδεσμος, coniunctio); and ‘article’ (ἄρθρον, articulus). The last they define naïvely as a little word which is all ending, and serves to distinguish the cases and numbers[102]. To the list of the parts of speech Antipater added the ‘mixed part’ or participle (μεσότης). The noun has four cases (πτώσεις), the ‘upright case’ (πτῶσις εὐθεῖα, casus rectus; this is of course a contradiction in terms); and the ‘oblique’ cases (πλάγιαι), that is the ‘class’ case (γενική), the ‘dative’ (δοτική), and the ‘effect’ case (αἰτιατική). The ῥῆμα or verb is identical with the κατηγόρημα or ‘predicate,’ and may take the ‘active’ form (ὀρθά), the ‘passive’ (ὕπτια), or the ‘neuter’ (οὐδέτερα); some verbs also express action and reaction, and are called ‘reflexive’ (ἀντιπεπονθότα). The Stoics also distinguished the tenses. Time (χρόνος) being of three kinds, past (παρῳχημένος), present (ἐνεστώς), and future (μέλλων), we have the following tenses which are ‘definite’ (ὡρισμένοι): the ‘present imperfect’ (ἐνεστὼς ἀτελής), the ‘past imperfect’ (παρῳχημένος ἀτελής), the ‘present perfect’ (ἐνεστὼς τέλειος), and the ‘past perfect’ (παρῳχημένος τέλειος); in addition to these we have the ‘indefinite’ tenses, the future (μέλλων), and the past indefinite, called simply indefinite (ἀόριστος)[103].

Theories of speech.

161. So far we find in the Stoic system the general framework of the grammar of the period, much of it adapted with modifications from Aristotle. In some other details points of real grammatical or philosophical interest are raised. Such is the controversy between ‘anomaly,’ the recognition of the individuality of each word in its flexion, and ‘analogy,’ in which the validity of the rules of declension and conjugation is insisted upon. Two Stoic masters, Chrysippus and Crates of Mallos, took up the cause of ‘anomaly[104].’ Further the Stoics held that all correct language exists by nature (φύσει), and not by convention (θέσει), as Aristotle had maintained; the elements of language being imitations of natural sounds[105]. Further, they held that the natural relation between ‘things’ (σημαινόμενα, significata) and the words that express them (σημαίνοντα, significantia) can frequently be determined by etymology; for instance φωνή ‘voice’ is φῶς νοῦ ‘the mind’s lamp,’ αἰών ‘age’ is ἀεὶ ὄν ‘enduring for ever[106].’ Like Heraclitus and Aristotle, the Stoics distinguished between ‘thought’ (λόγος ἐνδιάθετος, ratio) and ‘speech’ (λόγος προφορικός, oratio), which the Greek word λόγος tends to confuse[107]; thought is immaterial, but speech, as consisting of air in motion, is body[108]. Young children and animals do not possess real speech, but only ‘a sort of speech[109].’

Propositions and Syllogisms.

162. Words in combination form statements, questions, wishes, syllogisms, and so forth[110]; there is therefore no clear line drawn between what we call syntax and logic respectively. Whenever we have a complete combination of words expressing that which must either be false or true, as ‘Hannibal was a Carthaginian,’ ‘Scipio destroyed Numantia,’ we call it a ‘statement’ or ‘proposition’ (ἀξίωμα)[111]; for phrases of all kinds we have the more general term ‘phrase’ (λεκτόν, id quod dicitur)[112]. Of special interest is the conditional sentence (συνημμένον), which has two parts, the conditional clause (ἡγούμενον) and the contingent clause (λῆγον). The conditional or leading clause always contains a sign (σημεῖον), by means of which we reach proof: thus in saying ‘if it is day, it is light’ we mean that ‘day’ is a sign of light. Proof is ‘speech on every subject gathering what is less clear from that which is more clear[113].’ Its most important form is the syllogism, of which Chrysippus recognises five forms:

All these matters admit of endless qualifications, subdivisions, and developments, and were therefore serviceable to those Stoics who were before all things makers of books[115]. Examples of Stoic syllogisms have been given above[116].

Fallacies.