§§91--98. Summary: Dialectic cannot lead to stable knowledge, its processes are not applicable to a large number of philosophical questions (91). You value the art, but remember that it gave rise to fallacies like the _sorites_, which you say is faulty (92). If it is so, refute it. The plan of Chrysippus to refrain from answering, will avail you nothing (93). If you refrain because you _cannot_ answer, your knowledge fails you, if you _can_ answer and yet refrain, you are unfair (94). The art you admire really undoes itself, as Penelope did her web, witness the _Mentiens_, (95). You assent to arguments which are identical in form with the _Mentiens_, and yet refuse to assent to it Why so? (96) You demand that these sophisms should be made exceptions to the rules of Dialectic. You must go to a tribune for that exception. I just remind you that Epicurus would not allow the very first postulate of your Dialectic (97). In my opinion, and I learned Dialectic from Antiochus, the _Mentiens_ and the arguments identical with it in form must stand or fall together (98). §91. _Inventam esse_: cf. 26, 27. _In geometriane_: with this inquiry into the special function of Dialectic cf. the inquiry about Rhetoric in Plato _Gorg._ 453 D, 454 C. _Sol quantus sit_: this of course is a problem for φυσικη, not for διαλεκτικη. _Quod sit summum bonum_: not διαλεκτικη but ηθικη must decide this. _Quae coniunctio_: etc. so Sext. often opposes συμπλοκη or συνημμενον to διεζευγμενον, cf. esp _P.H._ II. 201, and Zeller 109 sq. with footnotes. An instance of a _coniunctio_ (hypothetical judgment) is "_si lucet, lucet_" below, of a _disiunctio_ (disjunctive judgment) "_aut vivet cras Hermarchus aut non vivet_". _Ambigue dictum_: αμφιβολον, on which see _P.H._ II. 256, Diog VII. 62. _Quid sequatur_: το ακολουθον, cf. I. 19 n. _Quid repugnet_: cf. I. 19, n. _De se ipsa_: the _ipsa_, according to Cic.'s usage, is nom. and not abl. Petrus Valentia (p. 301, ed Orelli) justly remarks that an art is not to be condemned as useless merely because it is unable to solve every problem presented to it. He quotes Plato's remarks (in _Rep._ II.) that the Expert is the man who knows exactly what his art can do and what it cannot. Very similar arguments to this of Cic. occur in Sext., cf. esp. _P.H._ II. 175 and the words εαυτου εσται εκκαλυπτικον. For the mode in which Carneades dealt with Dialectic cf. Zeller 510, 511. The true ground of attack is that Logic always _assumes_ the truth of phenomena, and cannot _prove_ it. This was clearly seen by Aristotle alone of the ancients; see Grote's essay on the Origin of Knowledge, now reprinted in Vol II. of his _Aristotle_.