[100] The chief divisions of the logic of the Stoics (Diog. 42, 46) are considered important for special purposes. The doctrine περὶ κανόνων καὶ κριτηρίων is of use, helping us to truth, by making us examine our notions; ὁρικὸν, because it leads to the knowledge of things by means of conceptions; διαλεκτικὴ (which includes the whole of formal logic), because it produces ἀπροπτωσία (= ἐπιστήμη τοῦ πότε δεῖ συγκατατίθεσθαι καὶ μὴ), ἀνεικαιότης (= ἰσχυρὸς λόγος πρὸς τὸ εἰκὸς, ὥστε μὴ ἐνδιδόναι αὐτῷ), ἀνελεγξία (= ἰσχὺς ἐν λόγῳ, ὥστε μὴ ἀπάγεσθαι ὑπ’ αὐτοῦ εἰς τὸ ἀντικείμενον), ἀματαιότης (= ἕξις ἀναφέρουσα τὰς φαντασίας ἐπὶ τὸν ὀρθὸν λόγον). Its value is therefore chiefly negative, as a preservative from error. See Seneca, Ep. 89, 9: Proprietates verborum exigit et structuram et argumentationes, ne pro vero falsa subrepant. Sext. Math. vii. 23: ὀχυρωτικὸν δὲ εἶναι τῆς διανοίας τὸν διαλεκτικὸν τόπον; Pyrrh. ii. 247: ἐπὶ τὴν τέχνην τὴν διαλεκτικήν φασιν ὡρμηκέναι οἱ διαλεκτικοὶ (the Stoics), οὐχ ἁπλῶς ὑπὲρ τοῦ γνῶναί τι ἐκ τίνος συνάγεται, ἀλλὰ προηγουμένως ὑπὲρ τοῦ δι’ ἀποδεικτικῶν λόγων τὰ ἀληθῆ καὶ τὰ ψευδῆ κρίνειν ἐπίστασθαι. [101] This may be seen in Sext. Pyrrh. ii. 134–203, 229; Math. viii. 300; as well as from the catalogue of the writings of Chrysippus in Diogenes. [102] The only part which is censured by Chrysippus (in Plut. Sto. Rep. 10, 1) is the sceptical logic, which leaves contradictions unsolved: τοῖς μὲν γὰρ ἐποχὴν ἄγουσι περὶ πάντων ἐπιβάλλει, φησὶ, τοῦτο ποιεῖν, καὶ συνεργόν ἐστι πρὸς ὃ βούλονται· τοῖς δ’ ἐπιστήμην ἐνεργαζομένοις, καθ’ ἣν ὁμολογουμένως βιωσόμεθα τὰ ἐναντία στοιχειοῦν. [103] Cic. Parad. Proœm.: Cato autem perfectus mea sententia Stoicus ... in ea est hæresi, quæ nullum sequitur florem orationis neque dilatat argumentum: minutis interrogatiunculis, quasi punctis, quod proposuit efficit. Cic. Fin. iv. 3, 7: Pungunt quasi aculeis interrogatiunculis angustis, quibus etiam qui assentiuntur nihil commutantur animo. See also Diog. vii. 18, 20. [104] In Sextus Empiricus, Διαλεκτικοὶ is their ordinary name. It is also found in Plut. Qu. Plat. x. 1, 2, p. 1008. Cic. Top. 2, 6; Fin. iv. 3, 6. [105] After the example of the Megarians, the Stoics were in the habit of putting their arguments in the form of questions. Hence the terms λόγον ἐρωτᾶν (Diog. vii. 186), interrogatio (Sen. Ep. 82, 9; 85, 1; 87, 11), interrogatiuncula (Cic.), which are employed even when the arguments were not in this form. [106] See p. 48, 1. [107] Called μέρη, according to Diog. 39 also τόποι, εἴδη, γένη.