The argument here recited must have been older than Diodorus, since Aristotle states and controverts it: but it seems to have been handled by him in a peculiar dialectic arrangement, which obtained the title of Ὁ Κυριεύων.[61] The Stoics (especially Chrysippus), in times somewhat later, impugned the opinion of Diodorus, though seemingly upon grounds not quite the same as Aristotle. This problem was one upon which speculative minds occupied themselves for several centuries. Aristotle and Chrysippus maintained that affirmations respecting the past were necessary (one necessarily true and the other necessarily false) — affirmations respecting the future, contingent (one must be true and the other false, but either might be true). Diodorus held that both varieties of affirmations were equally necessary — Kleanthes the Stoic thought that both were equally contingent.[62]
[61] Aristot. De Interpret. p. 18, a. pp. 27-38. Alexander ad Aristot. Analyt. Prior. 34, p. 163, b. 34, Schol. Brandis. See also Sir William Hamilton’s Lectures on Logic, Lect. xxiii. p. 464.
[62] Arrian ad Epiktet. ii. p. 19. Upton, in his notes on this passage of Arrian (p. 151) has embodied a very valuable and elaborate commentary by Mr. James Harris (the great English Aristotelian scholar of the 18th century), explaining the nature of this controversy, and the argument called ὁ Κυριεύων.
Compare Cicero, De Fato, c. 7-9. Epistol. Fam. ix. 4.
It was thus that the Megaric dialecticians, with that fertility of mind which belonged to the Platonic and Aristotelian century, stirred up many real problems and difficulties connected with logical evidence, and supplied matters for discussion which not only occupied the speculative minds of the next four or five centuries, but have continued in debate down to the present day.
Question between Aristotle and Diodôrus depends upon whether universal regularity of sequence be admitted or denied.
The question about the Possible and Impossible, raised between Aristotle and Diodorus, depends upon the larger question, Whether there are universal laws of Nature or not? whether the sequences are, universally and throughout, composed of assemblages of conditions regularly antecedent, and assemblages of events regularly consequent; though from the number and complication of causes, partly co-operating and partly conflicting with each other, we with our limited intelligence are often unable to predict the course of events in each particular situation. Sokrates, Plato, and Aristotle, all maintained that regular sequence of antecedent and consequent was not universal, but partial only:[63] that there were some agencies essentially regular, in which observation of the past afforded ground for predicting the future — other agencies (or the same agencies on different occasions) essentially irregular, in which the observation of the past afforded no such ground. Aristotle admitted a graduation of causes from perfect regularity to perfect irregularity:—1. The Celestial Spheres, with their included bodies or divine persons, which revolved and exercised a great and preponderant influence throughout the Kosmos, with perfect uniformity; having no power of contraries, i.e., having no power of doing anything else but what they actually did (having ἐνεργεία without δύναμις). 2. The four Elements, in which the natural agencies were to a great degree necessary and uniform, but also in a certain degree otherwise — either always or for the most part uniform (τὸ ὡς ἐπὶ τὸ πολύ) — tending by inherent appetency towards uniformity, but not always attaining it. 3. Besides these there were two other varieties of Causes accidental, or perfectly irregular — Chance and Spontaneity: powers of contraries, or with equal chance of contrary manifestations — essentially capricious, undeterminable, unpredictable.[64] This Chance of Aristotle — with one of two contraries sure to turn up, though you could never tell beforehand which of the two — was a conception analogous to what logicians sometimes call an Indefinite Proposition, or to what some grammarians have reckoned as a special variety of genders called the doubtful gender. There were thus positive causes of regularity, and positive causes of irregularity, the co-operation or conflict of which gave the total manifestations of the actual universe. The principle of irregularity, or the Indeterminate, is sometimes described under the name of Matter,[65] as distinguishable from, yet co-operating with, the three determinate Causes — Formal, Efficient, Final. The Potential — the Indeterminate — the May or May not be — is characterised by Aristotle as one of the inherent principles operative in the Kosmos.
[63] Xenophon, Memor. i. 1; Plato, Timæus, p. 48 A. ἡ πλανωμένη αἰτία, &c.
[64] Ἡ τύχη — τὸ ὁπότερ’ ἔτυχε — τὸ αὐτόματον are in the conception of Aristotle independent Ἀρχαί, attached to and blending with ἀνάγκη and τὸ ὡς ἐπὶ τὸ πολύ. See Physic. ii. 196, b. 11; Metaphys. E. 1026-1027.
Sometimes τὸ ὁπότερ’ ἔτυχε is spoken of as an Ἀρχή, but not as an αἴτιον, or belonging to ὕλη as the Ἀρχή. 1027, b. 11. δῆλον ἄρα ὅτι μέχρι τινὸς βαδίζει ἀρχῆς, αὔτη δ’ οὔκετι εἰς ἄλλο· ἔσται οὖν ἡ τοῦ ὁπότερ’ ἔτυχεν αὔτη, καὶ αἴτιοι τῆς γενέσεως αὐτῆς οὐθέν.