Theodor Ebert

In Defence of the Dialectical School

	In 1977, David Sedley published a paper in which, among other things, he argued that the Dialectical and the Megarian school were not, as had hitherto been assumed, two names for the same sect, although at different periods, but that both were distinct groups of Hellenistic philosophers.1 The received opinion, attacked by Sedley, based its claim on a passage in Diogenes Laertius (D. L.) concerning the disciples of Euclides of Megara, one of the minor Socratics: 

His followers were called Megarians after him, then Eristics, and at a later date Dialecticians, that name having first been given to them by Dionysius of Chalcedon (. . .). 	D. L. 2.106 = Giannantoni, SSR II A 222

The source of this text is probably Alexander Polyhistor, whose Successions of Philosophers are mentioned in the sentence preceding the one just quoted. Alexander lived around 100 B.C. Against this passage Sedley draws attention to a different piece of evidence in D. L., namely a verbatim quotation from Philippus the Megarian, who gives a list of people whom Stilpo won over to his own school, i. e. the Megarians; after having mentioned two persons whom Stilpo had made to secede from Theophrastus and two more who came from Aristotle the Cyrenaic philosopher, Philippus continues: 

From the Dialecticians he won over as devoted disciples Paeonius from Aristides, moreover Diphilus of Bosporus, the former follower of Euphantes as well as Myrmex the son (or ‘follower’) of Exaenetus, both of whom had come to refute him.	D. L. 2.113 = SSR II O 33 
							
Sedley concluded from this text that Megarians and Dialecticians could hardly be the same sect; the competition presupposed in this quotation from a contemporary of Stilpo clearly shows, thus Sedley, that Megarians and Dialecticians were seen as distinct schools by their contemporaries. As to the passage in D. L. 2.106, this is, as Sedley argues, probably a doxographical construction of a διαδοχή, a succession of philosophers; it is not the description of a school, or αἵρεσις.4
	Since Sedley’s main interest was in Diodorus Cronus, the most famous of the Dialecticians, he did not undertake to work out all the consequences of his discovery. Yet the fact that the title ‘Dialecticians’, for a certain period, was applied to a specific group of philosophers and not only used, as it is in Aristotle or Galen, to refer to logicians in general, together with the possibility of distinguishing these Dialecticians from the Megarians on the basis of Sedley’s seminal paper, made it a rewarding task to investigate the use of the words διαλεκτικός or διαλεκτικοί in other authors containing source material on Hellenistic philosophers. The most promising, although not the only candidate for such an investigation is Sextus Empiricus (S. E.). There are three passages in S. E. in which he reports doctrines held by the διαλεκτικοί: AM 8.93–126, PH
2.145–167 and 2.229–259. The theories reported concern a classification of propositions, a classification of (types of) inconclusive arguments and of sophisms respectively. The passages concerned were commonly taken to contain reports on Stoic logic. I did a close analysis of them and was eventually convinced that this material does not derive from Stoic logicians, but from the Dialecticians. I based my claim on a comparison with parallel accounts on the same topics that were undoubtedly Stoic, be it in S. E. or in D. L. In addition I tried to show that some of the other material in S. E. regarding logical matters (the theory of sign as reported in PH 2.104–106 and AM 8.244–256 and the theory of proof in AM 8.301–314 and PH 2.135–143) belongs to pre-Chrysippean or, as I labelled them, ‘early’ Stoics influenced by the Dialecticians.5 The main outcome of these investigations was that the Dialecticians played a much more significant role in the history of (propositional) logic than they had hitherto been given credit for. They, not the Stoics, were the true founding fathers of propositional logic. When we refer today to the antecedent and consequent as the parts of a conditional proposition, we still use technical terms introduced by the Dialecticians. Moreover, the Stoics predating Chrysippus were heavily influenced by and dependent on the logic of the Dialectical school.
	The claim made by Sedley distinguishing the Dialecticians from the Megarians and the one made by me attributing source material in S. E. which had been used for the Stoics to the Dialectical school, in general met with a friendly reception.6 Yet neither claim has gone undisputed. Klaus Döring, to whom we owe our first comprehensive collection of the material relating to the Megarians,7 launched an attack on Sedley’s contention;8 Döring sees no need to think of the Dialecticians as a separate school, distinct from the Megarians. Even before Döring’s 1989 paper, Robert Muller did not accept Sedley’s separation of the Dialecticians from the Megarians.9 The attribution of the material in S. E. to the Dialecticians, for which I had argued, was flatly denied by Jonathan Barnes.10 Hence, it may be worthwhile to look at the available evidence again in order to see whether Sedley’s and my original contentions can survive the criticisms of Döring and Barnes. I shall take the arguments of the two scholars in turn, starting with Döring.

I.

	Klaus Döring begins his investigation by comparing the attribution of ὁ Μεγαρικός and ὁ διαλεκτικός to specific philosophers. He points out that the characterization of someone as ὁ Μεγαρικός is rather rare: in Diogenes Laertius only the otherwise unknown Philippus, mentioned above, is thus labelled. In other authors Euclides, Ichthyas and Stilpo are each characterized as Μεγαρικός. On the other hand, the title ὁ διαλεκτικός is rather frequently given to philosophers in the tradition of Euclides, i. e. to Eubulides, Alexinus, Dionysius of Chalcedon, Diodorus Cronus and Philo.11 What is important for the question under discussion and a difficulty for Döring is the fact that there is no one who is given the title both of ὁ Μεγαρικός and ὁ διαλεκτικός.
	Since this fact tells against the main claim Döring wants to prove, he tries to marshal two other points in support of his thesis: First of all, he points out that the epitheton ὁ ἐριστικός is given to Clinomachus, Eubulides, Alexinus and Euclides (cf. SSR II A 27, II B 1, II C 14). Döring might have added to this list the name of Menedemus, whose name is found among the people called ἐριστικοί in the fragment in which Euclides is also characterized in the same way (SSR II A 27 = Döring (1972) fr. 40). Since Euclides certainly belongs to the Megarians, this case would show that a member of the Megarian school might also be called  ἐριστικός. And if we take Menedemus to be one of the followers of Stilpo, i.e. if we take him to belong to the Megarians, his would be the second case of a philosopher belonging to the Megarian school who is also called ὁ ἐριστικός. Since Clinomachus, Eubulides and Alexinus clearly are attested to be διαλεκτικοί, there can be no doubt that the title ὁ ἐριστικός covers members of the two groups, i.e. the philosophers called διαλεκτικοί and those called Μεγαρικοί.
	Yet I doubt that this fact can be used to support the claim that ‘Megarians’ and ‘Dialecticians’ are two names for the same group of Hellenistic philosophers. First of all, it is quite unlikely that the title ἐριστικός/ἐριστικοί, given the negative connotations of this term, was ever used by a person or a group to refer to themselves. And this sets it apart from Μεγαρικός/Μεγαρικοί and διαλεκτικός/διαλεκτικοί. Hence the title ἐριστικός/ἐριστικοί would have been given to the Megarians and Dialecticians by people which were critical of these groups. Secondly, the use made of the title ἐριστικός in one of the passages referred to above (i.e. SSR II A 27) is not in accordance with the text which is adduced to support the claim that ‘Μεγαρικοί’, ‘ἐριστικοί’and ‘διαλεκτικοί’ are names for the same group of people, i.e. D. L. 2.106 (SSR II A 22). For if Euclides, the founder of the whole group, can be called ἐριστικός, then this label can hardly be a name for these people which was given subsequently to them after they first were called Μεγαρικοί. Moreover, whereas there is ample evidence that οἱ διαλεκτικοί was the name given to a specific group of philosophers, in particular in the writings directed at them by other philosophers12, the title ἐριστικοί does not occur in the lists of several philosophical sects in Diogenes Laertius (cf. D. L. 1.17–21), lists in which the Dialectical school is mentioned more than once. Hence, it is not likely that the characterization of a philosopher as ὁ ἐριστικός is meant to classify him as a member of a specific sect. It may also be a way of referring to his general outlook or to his behaviour.
	A second piece of evidence Döring adduces for his position is a verbatim quotation from Chrysippus in Plutarch’s de Stoic. repugn. 10, 1036d-e (= SSR II O 28), in which Chrysippus refers to Μεγαρικὰ ἐρωτήματα.13 Döring claims that what Chrysippus must have in mind when using this phrase can hardly be anything other than those trick questions and fallacies which were the speciality of such philosophers as Eubulides, Alexinus and Diodorus Cronus. Döring continues:

Und wenn Chrysipp in einem weiteren von Plutarch im gleichen Zusammenhang und gleichfalls im Originalwortlaut zitierten Satz den zweifelsfreien Megariker Stilpon und seinen Schüler Menedemos wegen des Gebrauchs derartiger eristischer, sophistischer oder dialektischer Argumentationsformen, wie er sie Plutarch zu folge an anderer Stelle als Μεγαρικὰ ἐρωτήματα bezeichnete, vernichtend abqualifiziert, dann macht dies deutlich, daß man sie zu seiner Zeit mit Männern wie Eubulides, Alexinos und Diodoros Kronos in einen Topf warf und gemeinsam als Megariker titulierte.14

I for one do not think that Döring’s conclusion is justified by the text in Plutarch, even if we adhere to the report in Döring. The reasoning rests on the unproven assumption that the paradoxes and sophisms attributed to Eubulides, Alexinus and Diodorus were taken to be Μεγαρικὰ ἐρωτήματα. Yet it is at least equally possible that the Megarians had their own trick questions and fallacies, quite apart from those of the Dialecticians.
	This possibility proves to be a certainty if we look at the quotation from Chrysippus itself. For what Chrysippus warns against is the use of certain arguments in front of inexperienced people who may be diverted “by the dialectical questions of the Megarians or by others more numbersome and more cogent” (ὑπὸ τäν Μεγαρικäν ἐρωτημάτων καὶ ὑπ̓ ἄλλων πλειόνων καὶ δυναμικωτέρων ἐρωτημάτων. de Stoic. repugn. 10, 1036e, (= SSR II O 28), Cherniss’ translation). Thus, Chrysippus himself tells us that there were other arguments more forceful than the ones used by the Megarians, although belonging to the same genre as the Μεγαρικὰ ἐρωτήματα. And it is quite likely that these other arguments Chrysippus has in mind are those of people such as Eubulides, Alexinus and Diodorus. Even if we do not want to draw this conclusion, the quotation from Chrysippus, if read in its entirety, clearly does not support the conclusion Döring wants to draw from it, i.e. it does not put the fallacies and trick questions used by philosophers like Eubulides, Alexinus and Diodorus under the heading ‘Megarian arguments’.
	Nor does the fact that Cicero lists Stilpon, Diodorus Cronus and Alexinus in Acad. prior. II, 24, 75 (= SSR II C 8) as clever at trick questions suffice to show that these persons are members of the same sect, as Döring assumes.15 Moreover, we should be careful to distinguish between testimonies dating from roughly the period in which Megarians and Dialecticians were active, i.e. from the beginning to the middle of the third century B. C., and much later texts whose authors are bound to rely on reports about the philosophers they discuss. This is certainly the case with the reference in Philodemus’ Rhetoric to ‘Megarian dialecticians’ (SSR II C 13). Döring sees here the conflation of the two schoolnames and takes this to be a corroboration of his claim. Yet at the time of Philodemus’ activity (first century B. C.), the philosophical groups to which these names might apply were long extinct, and I think it is much more likely that Philodemus used the word ‘dialecticians’ in its quite usual sense of ‘logicians’.
	Döring points out that Epicurus wrote a treatise ‘Against the Megarians’ (D. L. 10.27)16 and he argues that the people criticized by Epicurus were not just Stilpo and his followers. His argument runs like this: Since Sedley had argued that Epicurus developed his theory of free will in opposition to the modal doctrine of Diodorus, a doctrine which was either meant or interpreted as deterministic, Döring thinks that the addressees of this Epicurean treatise might include also Diodorus. Yet this argument by Döring seems to presuppose what it is meant to demonstrate. Why should we assume that Epicurus did discuss Diodorus’ modal doctrine in a treatise directed against the Megarians, even if, as Döring explains, the Megarians Aristotle mentions in a passage of his Metaphysics (IX 3, 1046b29-32 = SSR II B15) identify potentiality and actuality?
	Döring then turns to the two testimonia which seem hardest for him to explain, first to the lists in D. L. in which we find the Megarian and the Dialectical school clearly distinguished. Döring thinks that it is the importance of Clinomachus for the development of logical questions that made later historians, especially those used in the Suda, set him up as the founder of a new sect, the Dialecticians.17 As for the list in D. L. itself, Döring points out that the ten ethical schools seem to be based on a construction: The five schools which are founded by direct disciples of Socrates, i. e. the Academy by Plato, the Cyrenaic school by Aristippus, the Elian school by Phaedo, the Megarian by Euclides and the Cynics founded by Antisthenes, are followed by five schools each of which in one way or another is derived from one of these: the Peripatetics from the Academy, the school of Epicurus from the Cyrenaics, the Eretrian school from the Elian, the Stoics from the Cynics, and finally the Dialectical school from the Megarians.18 If, thus Döring, the Dialetical school owes its place in this list to the principle underlying this construction, i. e. to find a follower for the Megarian school, then there is no need to accept it as a separate sect in the history of Hellenistic philosophy.
	Yet I do not think that this observation proves what Döring thinks it proves. If we had no other information concerning the Dialectical school, then we might conclude that its place in the list of the ten ethical sects is due to the construction of a historiographer. However, since we find the Dialecticians attested in other sources as well, there is no need to contest their status as a proper school alongside the other nine ethical sects. 
	The most difficult piece for Döring is, of course, the quotation from Philippus the Megarian in D. L. (2.113 = SSR II O 3) which, according to Sedley, is an „unimpeachable item of evidence testifying that the Dialecticians and the Megarians were entirely distinct schools at the end of the fourth century“.19 Döring’s argument here is directed against the claim (implicit in Sedley’s contention) that the Megarians can be regarded as a school. Döring tries to show that our evidence for a proper succession of scholarchs with the Megarians is very weak,20 that there is no evidence for a central place of instruction, like the Stoa Poikile for the Stoics, and that we have no evidence for a body of common convictions for the Megarians.21
	There are two points that can be made/raised against this argument. First of all, several other of the schools mentioned in D. L. will also fail to qualify as a school on one or the other of Döring’s criteria. D. L. himself states that the Pyrrhonians could not be regarded as a hairesis, if a set of positive doctrines is taken to be a prerequisite for a group of philosophers to be called a school (D. L. 1.20). Yet D. L. clearly wants them to be a proper sect. In a footnote Döring points out that the Elian and the Elian-Eretrian schools as well do not seem to have had a common body of convictions.22 Yet for D. L. they clearly count as schools. And do we have evidence for the succession of scholarchs in the Eretrian school?
	Secondly, even if we grant Döring his claims about the character of a school and if we go along with him in denying the Megarians their status as a philosophical sect, this does nothing to show that the Megarians and the Dialecticians as mentioned in the quotation from Philippus were one and the same group of philosophers. And this alone is the important point.
	Döring, however, thinks that a lack of common convictions is sufficient to explain that there was no obligation among the Megarians to exercise loyalty towards each other. And he continues in a footnote, commenting explicitly on the quotation from Philippus the Megarian: 
		 
Wenn die Verbindung der einzelnen Megariker untereinander so locker war, wie dies im vorigen beschrieben wurde, dann besteht kein Grund, es für unmöglich zu erklären, daß ein Megariker einem anderen Schüler abwarb.23 

	This seems to be a case of question-begging. The quotation from Philippus does not speak of one Megarian taking away disciples from another Megarian, but from the Dialecticians. And the Dialecticians in the quotation from Philippus are mentioned as being on a par with Theophrastus, on the one hand, and Aristotle, the Cyrenaic philosopher, on the other. Hence they are taken to be a school on the same level as the Peripatetics and the Cyrenaics.
	It is time to take stock: I do not think that Döring has proven his case. In particular, Döring has offered no convincing explanation of a situation between two competing groups of philosophers as described in the quotation from Philippus the Megarian. There can be no reasonable doubt that the Megarians and the Dialecticians were seen by their contemporaries as two distinct philosophical sects.

II.

	Let me then turn to the criticism offered by Barnes against the contention that the material in S. E. relating to people referred to as ‘dialecticians’ contains reports on the Dialectical school. It is perhaps necessary to point out at the outset that this question, although related to Sedley’s claim, is independent of it. The point at issue here is whether Sextus’ dialecticians are logicians quite generally or Dialecticians in the school sense. If the latter alternative should turn out to be wrong, this would not affect Sedley’s thesis at all, because there is still plenty of material to show that there was a Dialectical school distinct from the Megarians. On the other hand, even if there was no sharp distinction between the Megarians and the Dialecticians, as claimed by Sedley, it is still worthwhile to investigate the meaning of ‘dialecticians’ in S. E. If the Dialecticians and the Megarians are really one and the same school and if S. E.’s dialecticians belong to a specific sect and are not simply logicians, then S. E.’s reports provide source material for the Megarians (disguised as Dialecticians).
	Barnes takes issue with my claim that S. E. (at least sometimes) uses different sources in PH and AM. Against this he urges that we should stick to Janáček’s hypothesis that “Sextus copied from the same text twice and the differences between PH and M mark changes in his own stylistic habits and intellectual concerns” (Barnes 305). Barnes illustrates this criticism with my discussion of the ‘theory of sign’ as reported at AM, 8.244-56, PH 2.104 and Ps.-Galen historia philosopha chap. 9. I argued that there were three different texts (originating from Zeno, Cleanthes and Philo respectively) reported in the passages mentioned. This is, according to Barnes, a “romantic story”, and “(e)verything we know about the aims and methods of ancient doxography tells against” it (Barnes 304).
	My first point against Barnes is simply that whatever Janáček (allegedly or really) may have shown does not help us to explain the difference between the report in Ps.-Galen and the Sextian report in AM. And the difference exhibited in this case is in fact an incompatibility. The indicative sign is defined in AM as one that “does not admit of being observed together with the thing signified” (AM 8.154); the corresponding definition in Ps.-Galen states that the indicative sign “has not been beforehand observed together with thing signified.”24 Thus, the definition in Ps.-Galen does not demand that the thing signified cannot be observed together with the sign, as does the definition in S. E. The example given in Ps.-Galen “if this woman has milk, she has given birth” could not count as an indicative sign according to AM 8.154.25 
	Yet if there are different sources for the account we find in Ps.-Galen and in AM (and I for one do not see a more plausible explanation for their respective differences), then it is not excluded that S. E. too had access to different sources. After all, there were different accounts of sign between Aristotle and Chrysippus: we can read Aristotle’s account in the Analytics (An. pr. II 27), we know that Theophrastus as well as Zeno wrote a work On signs (cf. D.L. 5.15 and 7.4 resp.) and, as I have argued, taking a clue from a title in the list of Chrysippus’ writings (7.191), there is also evidence for a Philonian treatise on the subject. The theory of sign seems to have been a subject of hot debate in early Hellenistic philosophy. So why should the contention that these treatises were to become fountain-heads for different doxographical traditions be as absurd as Barnes takes it to be?
	We need not take Diels’ story in his Doxographi Graeci as the model for every ancient doxographical tradition. I can quote from Mansfeld Doxography and Dialectic who adopts a stance (against Diels) which I find quite congenial: “I would very much prefer to think of a tradition, or rather a plurality of traditions which remained fluid. Different versions, moreover, must have been in circulation simultaneously.”26 Since I take the circle of Arcesilaus to be the ultimate source of S. E.’s reports, I should like to point out that Mansfeld too sees the Sceptic Academy of Arcesilaus as a possible fountain-head for later traditions.27
	I do not see that Janáček’s useful observations on the relation of PH to AM 7–11 can be used to contradict my argument, as far as I am concerned with S. E. alone. Barnes has this on Janáček:

Janáček has argued that we should not think here of different sources – let alone of ultimate sources. Rather, Sextus copied from the same text twice, and the differences between PH and M mark changes in his own stylistic habits and intellectual concerns. Janáček’s hypothesis, which offers a uniform explanation for a common feature of Sextus’ writings, is preferable to E.’s hypothesis, which offers a special explanation for certain occurrences of the feature. 	Barnes 305

Barnes attributes to Janáček a much more general claim than Janáček is prepared to uphold. This is how Janáček describes his own procedure:

(. . .) Up to now every passage dealing with the same matter has been regarded as a parallel, but I take into consideration only those passages in which a definite relation between M VII – XI and PH can be ascertained, be it either the simple copying or the insertion or omission of a word, clause or sentence, the regular substitution of one or several words by others, etc. (. . .) For this reason I was not able to use parallels in M VII – XI, whose origin in PH could be disputed.28	

Janáček is interested in S. E. in his own right, and mainly in S. E. as a stylist. I am interested in S. E.’s sources. Hence, Janáček has undertaken a stylistic analysis of the Sextian texts, taking into account the use of certain particles, of constructions, of tenses, of synonyms etc. and disregarding aspects that have to do with the content of the Sextian treatises (in his case, a quite sensible procedure); as Janáček himself acknowledges in his book:

“I (. . .) deal only with the formal words viz. those words that have no connection with the contents, first of all particles.”
	Janáček, Prolegomena p. 11

In contradistinction to this procedure, I had to undertake a systematic analysis of the content of the passages discussed, taking into account the use of examples and of specific terms of logic, the types of classification used, specific definitions etc., i. e. aspects that would survive any stylistic changes an author reporting on other peoples’ theories might introduce into his material. Barnes’ criticism would be justified if I had used Janáček’s criteria in order to establish the use of different sources by S. E. But this is not what I have done. (It is worthwhile noticing that Janáček does not, as Barnes makes him do, argue against the assumption of different sources; as far as I can see, he simply does not tackle this question.) Hence, I am also unable to see why “Janáček’s arguments are based on a hypothesis which is incompatible with his (i.e. E.’s. - Th. E.) own thesis” (Barnes 305 n. 3). Janáček claims that PH is prior to AM 7–11; I argue that S. E. in the later work sometimes used sources preceding the ones used in the earlier work. Thus, I attribute AM 8.244–256 and 8.301–314 to Zeno, the corresponding passages in the earlier work, i.e. PH 2.104–106 and PH 2.135–143, to Cleanthes. 
I do not think that this is incompatible with the hypothesis underlying Janáček’s work that S. E. often (not always) is rewriting his earlier work in AM.29
	Barnes also raises a doubt as to whether the word ‘διαλεκτι-κός’/‘διαλεκτικοί’ is ever used to refer to the Dialecticians in S. E.:

The phrase ‘ἡ Διαλεκτικὴ <αἵρεσις>’ is indeed used as a ‘school name’, in four or five late and fuddled texts. But it is not clear to me that the adjective ‘διαλεκτικός’ is ever used to indicate membership of this sect; and the word ‘οἱ διαλεκτικοί’ – like the word ‘dialectici’ in Latin – is standardly used as a vague and general denotation: ‘The logicians say . . .’ (see p. 146). And yet E. supposes that sometimes, and without any signal, Sextus – who himself never refers to the Dialectical School – intends his readers to understand it as a School-name. 	Barnes 305

Among the “late and fuddled texts” is D. L. He is only slightly later than S. E.  And D. L. clearly knew a Dialectical school (cf. 1.18, 19, 20). The word διαλεκτικοί as a designation of this school is also attested in D. L. (cf. 1.17, 2.106, 113), D. L. 2.113 being proof that this was their designation while these philosophers were still active and alive. Moreover, there are contemporary authors who wrote against οἱ διαλεκτικοί, thus Ariston (D. L. 7.163), Metrodorus (D. L. 10.24) and the διαλεκτικοί also turn up in one title in the list of Chrysippus’ writings (D. L. 7.202). Epicurus calls the διαλεκτικοί despoilers, in a context in which he abuses a number of other schools and their founders. The Cynics are mentioned here just before the διαλεκτικοί and Pyrrho just after them (D. L. 10.8). I cannot see how, given this evidence, it can be denied that οἱ διαλεκτικοί was used as a designation to refer to the Dialectical school.
	To Barnes it is not clear “that the adjective ‘διαλεκτικός’ is ever used to indicate membership of this sect”. I confine myself to those philosophers to whom the epitheton ὁ διαλεκτικός is attributed in D. L.: Dionysius of Chalcedon (2.98), Panthoides (5.68), Philo (7.16), Artemidorus (9.53); moreover, Diodorus Cronus (2.111) and a Heraclides from the town Bargylia who wrote against Epicurus (5.94) are chracterized as belonging to the Dialecticians. More names can be found in Sedley (1977).30 What is perhaps as telling is the fact that the title ‘διαλεκτικός’ is never given to such philosophers as Euclides, Stilpo or Chrysippus, all of them certainly important logicians. How is this to be explained on Barnes’ reading of the texts?
	The text from Barnes quoted above continues

I find this hard to believe. And so does E. For, under textual pressure, he suggests that Sextus ‘was not clear’ about the use of the word as a School-name (p. 146 n. 13). Later, he conjectures that the word had a capital delta in Sextus’ source but that Sextus either misconstrued it as a general term or was unsure whether to take it in the general or the historical sense. In that case, E. should not admit a capital delta into his text of Sextus – and his chief reason for ascribing any Sextan passage to the Dialecticians vanishes.	Barnes 305

Let us allow Barnes his little caricature of Ebert putting capital deltas in S. E.’s sources. What I claim is this: There are two passages, i.e. PH 2.166 and 2.235, in which S. E. makes use of the term οἱ διαλεκτικοί in such a way that this term refers to logicians generally, but these passages cannot detract from the value of the passages in which S. E. reports on theories of the Dialecticians. Why not? Because the two passages concerned occur in S. E.’ comments, not in his reports, a point I had expressly drawn attention to31 (something ignored by Barnes). That may not be the sort of signal Barnes would like to see, but the distinction between what an author reports and what he expresses as his own opinion is certainly not alien to an analysis of ancient doxography. It may also be significant that both cases of this usage occur in PH, according to Janáček the earlier work, not in AM. Of course, the usage of this term by S. E. raises the question whether S. E. was deliberately switching from the historical to the systematic meaning of the term or whether he took his sources to report on logicians in general. I do not think that the texts allow a definite answer to this question, but I do not think either that a sceptical ἐποχή as to S. E.’ intention in this matter need prevent us from reading his reports on the ‘dialecticians’ as sources for the Dialectical school. My main argument for this reading of the Sextian texts reporting on ‘dialecticians’ rests on comparing the doctrines reported by S. E. to theories that are undoubtedly Stoic. The differences that emerge from this comparison provide sufficient evidence for the non-Stoic origin of these doctrines.
	The passage in S. E. which to my mind is the most obvious example of a report on doctrines of the Dialectical school is AM 8.93–126. So it is no wonder that Barnes directs his fire against my reading of this passage. This text discusses a classification of propositions, and I argued that this classification derives from the Dialectical school. I supported my claim by several arguments, first of all by  a comparison between this classification and the Stoic classification of propositions preserved in D. L. 7, first concentrating on what both texts have to say on simple propositions, i.e. those without a connecting particle.32 S. E. reports a threefold classification, dividing simple propositions into definite (ὡρισμένον), indefinite (ἀόριστον) and intermediate (μέσον) ones (AM 8.96f.); D. L., however, gives a list of six groups, labelled respectively as negative (ἀποφατικόν), negatively assertoric (ἀρνητικόν), privative (στερητικόν), categorical (κατηγορικόν), predicative (καταγορευτικόν), and indefinite (ἀόριστον) (D. L. 7.69f.) 
	The opinion of scholars on these texts was that S. E.’ threefold classification of simple propositions is a truncated version of what we find in D. L.33 S. E.’ three classes of simple propositions seemed to correspond grosso modo to the three last groups in Diogenes’ list. However, there is reason to doubt this opinion. First of all, there is nothing in the Sextian report indicating that his list of simple propositions is not complete. It should be noted that S. E., when dealing with non-simple propositions, does indeed indicate that his list is not complete (cf. AM 8.124). Now, even if S. E. does not give us any direct hint as to the presumed incompleteness of his list of simple propositions, this will perhaps not be sufficient to establish that this list is meant to be complete. Yet there is a second and more forceful argument to prove this point. One of the three classes of simple propositions in S. E. is called intermediate (μέσον), literally ‘middle’. It seems to be clear that talk of a ‘middle’ would not make sense when there are, as in the list in D. L., six items: the number of items would have to be odd, not even, for there to be a middle. And what is more: In all other cases in which ‘middle’ is used as a technical term in a list of terms designating non-spatial objects, these lists contain three and only three terms, they are triads. Thus, the Greek word is used for the grammatical medium, and, in mathematics, for the mean proportional. In his syllogistic, Aristotle labels the term occurring only in the premisses the middle term, and he uses μέσον for the second of his (three!) syllogistic figures. Hence, I concluded that the list of simple propositions in S. E. is meant to be complete and that it cannot be part of the list in D. L. These two lists therefore stem from two different sources. 
	Yet this will not suffice to show that the list in S. E. derives from the Dialecticians. To make good this claim, I had to move on to what S. E. tells us about non-simple propositions. Again, the list of these propositions in S. E. and the one in D. L., although this time there is no difference in terminology, cannot stem from the same source for in D. L. the conditional proposition is defined using the Stoic criterion of cohesion (συνάρτησις); according to this criterion a conditional is “true if the contradictory of its consequent is incompatible with its antecedent” (D. L. 7.73). In the passage from S. E. under discussion the two criteria discussed are the truthfunctional one championed by Philo (AM 8.113), on the one hand, and the criterion advocated by Diodorus on the other; Diodorus strenghtened Philo’s criterion so that a conditional is true if “it neither was nor is able to begin with something true and end with something false” (AM 8.115). It should be clear that the Stoic criterion and the Diodorean one are not equivalent: the conditional “if 10 is a prime number, then it is not the case that 10 is a prime number” is true according to Diodorus, since it neither was nor is able to begin with something true because of the falsity of its antecedent, and false according to the criterion of cohesion, since the negation of the consequent is equivalent to its antecedent and, hence, cannot be incompatible with it. I concluded again that the two lists are derived from different sources. Now the list in S. E. mentions explicitly two philosophers, i. e. Philo and Diodorus, who both were members of the Dialectical school. No other philosopher or other philosophical sect is mentioned in AM 8.93–129, although in the text preceding AM 8.93 (i.e. 8.67–90) the Stoics are mentioned quite often. Although the Stoics discussed in AM 8.67–90 are clearly Stoic logicians, they are never referred to as ‘dialecticians’. These findings convinced me that what S. E. found in his sources about a classification of propositions with the dialecticians has to be attributed to the Dialecticians.
	Barnes does not comment on the differences between the material in S. E. and in D. L. Nor does he say anything about the conspicuous absence of words referring to the Stoics in AM 8.93–129, where we find a report on dialecticians, or on the absence of the word διαλεκτικοί in the text of AM 8.67–90, where logical doctrines of the Stoa are discussed. He focusses on the Philo/Diodorus part of my argument. Here is what he reports of my argument on AM 8.93–129:

At 112–19 Sextus retails the διαφωνία among οἱ διαλεκτικοί over the analysis of conditional propositions. He names only Philo and Diodorus, both of them Dialecticians. Hence in 112, 118 and 119 we must print a capital delta; and since we cannot suppose a change in use within 93–129, we must print the capital throughout and ascribe the whole section to the Dialecticians.
	Barnes 305

Now to Barnes’ critique:

The argument is frail, its consequences bizarre. The views of Philo and Diodorus are offered as illustrations, παραδείγματα (118), of the στάσις among ‘all the διαλεκτικοί’ (112). We infer that Sextus knew the views of other διαλεκτικοί, an inference confirmed by his remarks in 119. Thus according to E., other Dialecticians held other views on conditionals, views which were known to Sextus and which have left no trace elsewhere in the literature. Again, at PH 2.110–112 and M 8.265, where Sextus once more refers to a dispute over conditionals, E. must suppose that he has a different διαφωνία in mind, one which involved Philo and Diodorus (but no other Dialecticians), and also members of other schools. (. . .) Sextus, of course, drops no hint that he knows of different διαφωνίαι, one intersectarian and one intrasectarian.	Barnes 305f.

So Barnes’ main argument is based on the fact that S. E. in two other passages, i. e. in PH 2.110–112 and M 8.265, has a fuller list of contenders in the debate on conditionals; the additional contenders include those upholding the Chrysippean criterion of cohesion (συνάρτησις) (PH 2.111; AM 8.265) and still another criterion, that of ἔμφασις (PH 2.112). Since we do not know of further philosophers from the Dialectical school in this debate (and since S. E. must on my reading refer to other Dialecticians at AM 8.112–129), it is more economical, thus Barnes, to suppose that the other dialecticians presupposed by S. E. at AM 8.112 and 119 are simply those logicians who are explicitly referred to in these other passages. “Plainly”, thus Barnes, “8.112–19 gives a truncated report” (Barnes 306) of the debate as reported in these other passages.
	There are two prima facie observations that tell against this Barnesian reading. First of all, the text of AM 8.112–119 which, according to Barnes, contains a truncated report of the debate on conditionals, is by far the longest and most explicit of the three texts. It seems at least somewhat strange to suppose that S. E. who provides so much space for the discussion of the criteria for the conditional in AM 8.112–119 left out the views of the Stoic logicians whose criterion is mentioned in the other two texts, if S. E. (or his source) did use ‘dialecticians’ for logicians, including Stoic logicians, quite generally at AM 8.112–119. Secondly, in neither of the other two Sextian texts discussing the criteria for the conditional are the logicians involved labelled ‘dialecticians’. These two observations tell in favour of the school name reading of this term.
	Barnes main argument is based on an inference: “The views of Philo and Diodorus are offered as illustrations, παραδείγματα (118), of the στάσις among ‘all the διαλεκτικοί’ (112). We infer that Sextus knew the views of other διαλεκτικοί, an inference confirmed by his remarks in 119.” And Barnes is happy to saddle me with a consequence of this inference, probably one of the ‘bizzare’ consequences: “Thus according to E., other Dialecticians held other views on conditionals, views which were known to Sextus and which have left no trace elsewhere in the literature.” This is in Barnes’ mind a “reductio ad absurdum” (Barnes 306). 
	Does this reasoning stand scrutiny? I do not think so. First of all, the most that can be safely inferred from Sextus’ remarks at 8.112 and 119 is that he knew that there were other contenders in the debate among the Dialecticians, not that he knew their views. His sources might have told him just as much, but not more. Secondly, why is the idea that other Dialecticians held views on the truth criteria for the conditional as outlandish as Barnes takes it to be? Philo and Diodorus were not the only Dialecticians, but as for other Dialecticians, we quite often know only their names, nothing about their theories. Why should not some of these Dialecticians have come up with opinions of their own about an issue hotly debated by two prominent members of their sect? Of course, their views left no trace in the extant literature, but even the views of Philo and Diodorus would have remained unknown to us, were it not for the work of S. E.
	Yet even if we grant that S. E. knew the views of other Dialecticians about the criterion of the conditional, why should he have bothered to include them in his report, given that the theories of Philo and Diodorus offer such a nice and easy-to-grasp contrast?
	Barnes thinks that “Sextus’ text gives no answer” to the question “which logicians originated the classification” at AM 8.93–126 (Barnes 306 n 10). One thing, however, should be clear: Since Philo and Diodorus, the only logicians mentioned in this passage, were not Stoics and did not depend in their logical views on Stoic philosophers, the passage in S. E. cannot be taken to inform us throughout on Stoic logic. Hence Barnes’ claim (same note) “the orthodox view, that the Stoics are behind it all, is surely true” to me looks plainly wrong. Moreover, how is Barnes to explain the differences between the classification in D. L. and that in S. E.?
	It is again time to take stock. I think that what Barnes claims about the use of the term ‘dialectician(s)’ generally, i. e. in authors other than S. E., is evidently wrong. The usage attested in D. L. alone is sufficient to show not only that there was a Dialectical school, but also that philosophers belonging to this school were collectively called ‘διαλεκτικοί ’ and that the singular ὁ διαλεκτικός was used to characterize individual philosophers as belonging to this sect. I for one cannot see how Barnes can uphold his thesis on the meaning of ὁ διαλεκτικός/οἱ διαλεκτικοί in the light of the material gathered in Sedley’s paper proving that both terms were used to refer to members of a specific philosophical school. As for S. E., matters are not quite as transparent, but the fact that the words ὁ διαλεκτικός/οἱ διαλεκτικοί were used to refer to philosophers belonging to the Dialectical school, as shown above, makes it at least possible that these words in S. E.’ reports had the same (school-name) meaning. This possibility may well be strengthened by the fact that in these reports S. E. never refers to Stoic logicians. The close comparison of these reports with parallel accounts in Stoic material, as exemplified in the case of the classification of propositions in S. E., on the one hand, and in D. L. 7 on the other, should suffice to establish that what S. E. reports concerns logicians predating the Stoa. I do not think that this result can be shaken by the main point Barnes raises against my claim, i.e. the fact that S. E. in two passages uses ‘dialecticians’ in a systematic sense, since in these passages S. E. is no longer reporting, but commenting on his reports.
	Hence I remain convinced not only that the Dialecticians were recognized as a proper philosophical school by their contemporaries, but also that S. E. in his reports on the ‘dialecticians’ has preserved a precious treasure containing information about specific theories of these philosophers.34

								Theodor Ebert
	Universität Erlangen-Nürnberg