Hostname: page-component-7c8c6479df-8mjnm Total loading time: 0 Render date: 2024-03-19T07:19:29.468Z Has data issue: false hasContentIssue false

CAUSING DOUBTS: DIODORUS CRONUS AND HEROPHILUS OF CHALCEDON ON CAUSALITY*

Published online by Cambridge University Press:  20 November 2014

David Leith*
Affiliation:
University of Exeter

Extract

The physician Herophilus of Chalcedon, who lived and worked in Alexandria in the early third century b.c., is best known and justly celebrated for his numerous and ground-breaking anatomical discoveries and advances in such areas as pulse theory. His systematic investigations into the human body led to some of the highest achievements of Hellenistic science, among which the best known is probably his discovery and detailed description of the nervous system and its functions. Yet certain aspects of his thought have seemed difficult to harmonize with the aims and methods of his medical research. One such is his attitude to causality. According to Galen, Herophilus had accepted the existence of causes merely on a hypothetical basis, and indeed had made the striking claim that ‘by nature it is not discoverable whether causes do or do not exist’. Galen associates these views directly with a number of arguments designed to prove that there are no such things as causes, but we are otherwise left with little in the way of context, and different interpretations have unsurprisingly suggested themselves.

Type
Research Article
Copyright
Copyright © The Classical Association 2014 

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

Footnotes

*

My sincere thanks are due to Nicholas Denyer for extremely helpful comments on an earlier draft of this paper, as well as to CQ's anonymous reader. I am very grateful to Philip van der Eijk for the opportunity to discuss the paper in detail at a colloquium on ancient medicine and philosophy at the Humboldt University, Berlin: I would like to thank all the participants, and in particular Hynek Bartoš, Philip van der Eijk, Orly Lewis, Oliver Overwien, Chiara Thumiger, and Roland Wittwer. I also gratefully acknowledge the support of the Wellcome Trust (grant no. 091617).

References

1 For Herophilus in general, see the magisterial study of von Staden, H., Herophilus: The Art of Medicine in Early Alexandria (Cambridge, 1989)Google Scholar. For Herophilus' pulse theory, see ibid., 262–88; for his discovery of the nervous system, ibid., 155–61, 247–59, and Solmsen, F., ‘Greek philosophy and the discovery of the nerves’, MH 18 (1961), 150–97, esp. 184–97Google Scholar. Herophilus' researches into the reproductive system were also ground-breaking, leading for example to his identification and description of the ovaries: see von Staden (this note), 165–9.

2 Gal. CP 162 and 198 respectively (pp. 128 and 146 Hankinson) = T58 and T59a von Staden, to be examined in detail below. It has been of enormous help to have at my disposal the excellent edition, translation, and commentary of Galen's CP in Hankinson, R.J., Galen: On Antecedent Causes (Cambridge, 1998)Google Scholar.

3 Kudlien, F., ‘Herophilus und der Beginn der medizinischen Skepsis’, Gesnerus 21 (1964), 113Google Scholar (repr. in Flashar, H. [ed.], Antike Medizin [Darmstadt, 1971], 280–95)Google Scholar. Further arguments marshalled by Kudlien in support of Herophilus' scepticism are effectively countered by von Staden (n. 1), 117–24 and 244–7.

4 See von Staden (n. 1), 115–24, and e.g. 121: ‘Herophilus finds in the provisionality which a “suppositional” (ex hypothesi) causal explanation can accommodate a key to reconciling his extensive empirical or observational activity with a guarded form of theory formation.’

5 Hankinson, R.J., ‘Saying the phenomena’, Phronesis 35 (1990), 194215, at 208–12CrossRefGoogle Scholar; Hankinson (n. 2),` 270–9, esp. 279: ‘Herophilus means thus to jar us out of our causal complacency, to make us realize that the offering of causal explanations is a difficult and inherently unstable enterprise. To this end he employs arguments which would eliminate, if successful, far more than simple unreflective over-confidence – but his goal is not that we actually accept them; merely that we are shaken by them.’

6 Sext. Emp. Pyr. 2.245 = T15 von Staden = fr. 127 Döring = fr. 17 Giannantoni; trans. Annas and Barnes.

7 Sext. Emp. Pyr. 2.242; trans. Annas and Barnes. On Diodorus' various arguments against motion, see Sedley, D., ‘Diodorus Cronus and Hellenistic philosophy’, PCPhS 23 (1977), 74120, at 84–9Google Scholar; Döring, K., ‘Die sogenannten kleinen Sokratiker und ihre Schulen bei Sextus Empiricus’, Elenchos 13 (1992), 81118, at 98–118Google Scholar.

8 Pyr. 3.71 = fr. 124 Döring = fr. 16 Giannantoni; Math. 10.87–90 = fr. 123 Döring = fr. 13 Giannantoni; and Math. 1.311 = fr. 128 Döring = fr. 18 Giannantoni.

9 Fr. 393 Pfeiffer. When the crows caw κῶς αὖθι γενησόμεθα (‘How shall we get there?’), that the reference is to Diodorus' argument against motion and his underlying theory of spatial and temporal minima is argued convincingly by White, M.J., ‘What worried the crows?’, CQ 36 (1986), 534–7.CrossRefGoogle Scholar

10 See Oppermann, H., ‘Herophilus bei Kallimachos’, Hermes 60 (1925), 1432Google Scholar. Most, G.W., ‘Callimachus and Herophilus’, Hermes 109 (1981), 188–96Google Scholar, also argues, more speculatively, for an allusion in the Hymn to Delos to Herophilus' obstetric innovations.

11 It may also be observed that at Aëtius, Placita 1.23, Herophilus' views on the perceptibility of motion are closely associated with Diodorus' theory of motion. Also worth mentioning is the fact that Galen once describes Herophilus as ἐκεῖνον τὸν διαλεκτικόν (Gal. MM 1.3 [10.28K.] = T10 von Staden). Although this must be simply a general characterization of Herophilus' perceived skill in logic or dialectic, the epithet Διαλεκτικός was also that standardly attached to Diodorus and his pupils as a school label: see Sedley (n. 7), 74–7; see also Denyer, N., ‘Neglected evidence for Diodorus Cronus’, CQ 52 (2002), 597600CrossRefGoogle Scholar. Galen apparently never uses the epithet in this latter sense, but his usage here at least points to something distinctive about Herophilus' style of argumentation which may be relevant to our understanding of the anecdote linking him with Diodorus (in his commentary on this passage, von Staden [n. 1], 61–2, also points to Herophilus' use of diaeresis in analysing various aspects of medicine).

12 As noted, Callimachus refers to Diodorus as an apparently well-known public figure (Sext. Emp. Math. 1.309 = fr. 393 Pfeiffer). Diodorus is also found at a banquet presided over by Ptolemy I Soter in a further anecdote (Diog. Laert. 2.111–12 = fr. 99 Döring = fr. 1 Giannantoni); see Sedley (n. 7), 80, for persuasive arguments that this must have occurred in Alexandria, and that the context of the story is likely to have been historically accurate, if not the details. Sedley concludes that Diodorus died in Alexandria c. 284 b.c., and this has been generally accepted. Herophilus' medical achievements are ubiquitously associated with Alexandria; his dates are extremely difficult to pin down with any precision, but the evidence we have concurs in locating his floruit in the early third century b.c.: see von Staden (n. 1), 43–50.

13 Allen, J., ‘Galen as (Mis)informant about the views of his predecessors’, AGPh 83 (2001), 81–9CrossRefGoogle Scholar, argues, I think rightly, that Galen has seriously misunderstood, or at least misrepresented, Erasistratus' position.

14 Gal. CP 162 (p. 128 Hankinson) = T58 von Staden: quidam enim nil nullius dixerunt existere causam, quidam vero dubitaverunt si est an non, sicut Empirici, quidam autem ex suppositione acceperunt, sicut Erophilus, alii vero quidam, quorum ipse fuit dux (sc. Erasistratus), procatarticas causarum removerunt ut male creditas (‘For some people have said that nothing is the cause of anything else; some have been uncertain as to whether anything is or not, like the Empiricists; others, like Herophilus, have assumed them on the basis of hypothesis; and others, of whom he [sc. Erasistratus] was the leader, have thrown out antecedent causes as falsely believed in’; trans. Hankinson). For clarification that the final authority referred to must be Erasistratus rather than Herophilus, see Hankinson (n. 5), 208 n. 28, and, more fully, Hankinson (n. 2), 253–4.

15 Gal. CP 197–200 (pp. 146–8 Hankinson) = T59a von Staden; trans. Hankinson, with changes. The supplements to the text in § 199 are due to Bardong, and they adequately restore the required sense. It is perhaps doubtful whether, strictly speaking, they should be restored to Niccolò's Latin translation, since the omissions seem more likely to have occurred in the original Greek text than in the Latin: cf. the opportunities for confusion in the parallel formulations at Sext. Emp. Math. 10.210 and 227.

16 It is scarcely to be doubted that Galen drew these arguments directly from Herophilus' writings. It would seem absurd to suppose that he took the arguments from elsewhere, merely speculating that they were the sorts of considerations which could hypothetically have generated Herophilus' doubts. We have very strong reasons for thinking that Galen knew at first hand at least some of Herophilus' oeuvre, from which he preserves extensive quotations (see von Staden [n. 1], 70). These passages from Galen's CP are also the only ancient witnesses to Herophilus' sceptical attitude towards causes, while the arguments themselves are mentioned nowhere else in the Galenic corpus, and thus appear to be tied to this specific context.

17 Quotations from Herophilus' original works are rare, but a good example derives from his Midwife, where he offers a list of causes of dystocia, recorded by Soranus at Gyn. 4.1.4–5 = Fr196 von Staden: note in particular Herophilus' statement that καὶ τὸ ἐν ὀσϕύι δὲ καὶ ῥάχει γινόμενον κοίλωμα αἴτιον δυστοκίας γίνεται, καὶ διὰ πιμελῶδες ἐν ἐπιγαστρίῳ καὶ ἐν ἰσχίῳ δυστοκία γίνεται ὡς ἂν ἀποπιεζομένης τῆς μήτρας, καὶ διὰ τὸ τεθνηκέναι τὰ ἔμβρυα (‘when a concavity arises in the loin and spine, it, too, becomes a cause of difficult labour; on account of fat in the upper abdominal cavity and in the hips, difficult labour also occurs as if the uterus is squeezed, and because the foetuses are dead’). See generally von Staden (n. 1), 302: ‘For all Herophilus’ emphasis on the provisionality and hypothetical nature of causal explanation, the evidence presented in this chapter (especially T205–T225) leaves no doubt that Vindician is right [sc. to say that Herophilus dissected cadavers to discover why they died], at least to the extent that Herophilus engaged in causal explanation not only for physiological but also for pathological purposes.' I shall consider Herophilus' views about the causes of disease in more detail below.

18 See esp. Gal. CP 46–55 (pp. 84–8 Hankinson); see also CP 97 (p. 102 Hankinson), which appears to link the two passages.

19 For a useful discussion of Galen's attitudes to the proper use of language and terminology in a scientific or philosophical context, see Morison, B., ‘Language’, in Hankinson, R.J. (ed.), The Cambridge Companion to Galen (Cambridge, 2008), 116–56, esp. 148–52CrossRefGoogle Scholar.

20 Gal. CP 53 (pp. 86–8 Hankinson). Note that Galen wrote a whole book on How one ought to distinguish an inquiry into things from one into word and meaning (ὅπως χρὴ διακρίνειν τὴν πραγματικὴν ζήτησιν τῆς κατ᾽ ὄνομα καὶ τὸ σημαινόμενον ἕν, Gal. Libr. Propr. 14.20 [19.44 K.]), and another work On the inquiry into word and meaning (περὶ τῆς κατ᾽ ὄνομα καὶ σημαινόμενον ζητήσεως, Libr. Propr. 14.23 [19.45 K.]).

21 See Barnes, J., ‘Ancient skepticism and causation’, in Burnyeat, M.F. (ed.), The Skeptical Tradition (Berkeley, CA, Los Angeles, CA, and London, 1983), 149203, at 150–3Google Scholar; Hankinson (n. 2), 272–3; Cambiano, G., ‘Philosophy, science and medicine’, in Algra, K. et al. . (edd.), The Cambridge History of Hellenistic Philosophy (Cambridge, 1999), 585613, at 610CrossRefGoogle Scholar; and Allen (n. 13), 83.

22 Sext. Emp. Math. 9.195; trans. Bury, with minor changes.

23 Sext. Emp. Math. 10.46–48 = fr. 122 Döring = fr. 12 Giannantoni; these are the only authorities named.

24 See Sedley (n. 7), 77–8.

25 This despite Sextus' misattribution to them at Math. 10.47 of Zeno of Elea's Dichotomy argument against motion: see Sedley (n. 7), 84. For Parmenides' arguments against motion, see DK 28 B 8.26–31; for Melissus', DK 30 B 7.7–10.

26 In the whole section on motion at Math. 10.37–168, Diodorus' arguments and the responses to them are addressed explicitly at §§48, 85–118, 143; §§119–20 can also be added, though Diodorus is not mentioned (see Denyer, N., ‘The atomism of Diodorus Cronus’, Prudentia 13 [1981], 3345, at 34–7)Google Scholar.

27 See Sext. Emp. Math. 10.99, 112, 118; see also the anecdote told of ‘one of the ancient Cynics’ and an anonymous sophist at Math. 10.68, where the context suggests Diodorus: cf. Sext. Emp. Pyr. 2.244, and Diog. Laert. 6.38–39, where the same anecdote is told of Diogenes, and where Diodorus' Horned argument is additionally refuted in a parallel manner.

28 Classen, C.J., ‘L'esposizione dei sofisti e della sofistica in Sesto Empirico’, Elenchos 13 (1992), 5779, at 59–61Google Scholar, referring to Sext. Emp. Pyr. 2.245, which is, perhaps not incidentally, the anecdote about Herophilus and Diodorus.

29 Epicurus, Nat. 28 fr. 13 col. IX 11–IX 20; see comm. ad loc. in Sedley, D., ‘Epicurus, On Nature Book XXVIII’, CErc 3 (1973), 583, at 71–3Google Scholar. See also Plut. Stoic. Rep. 1036F, where Chrysippus criticizes Diodorus' associate and rival, the Megarian philosopher Stilpo, for having descended into sophistry; and Cic. Acad. 2.75, where both Stilpo and Diodorus are accused of using sophismata.

30 Sext. Emp. Pyr. 1.234 reports that Arcesilaus' contemporary Ariston of Chios described him as ‘Plato in the front, Pyrrho at the back, and Diodorus in the middle’, because he made use of Diodorus' dialectic; see Sedley (n. 7), 83.

31 See Sedley (n. 7), 110 n. 56: ‘Diodorus is also likely to be the author of an argument against becoming, quoted by Sext. Emp. (Pyr. 2.243, in a catalogue of sophisms where the two preceding arguments, though also unattributed, are of Diodorean origin): “What becomes is either τὸ ὄν or τὸ μὴ ὄν; but neither ..... etc.” (of course, nothing beyond the formal presentation of this argument is original; in other respects it is that attributed to the “ancients” by Aristotle, Ph. A, 191a 23–33)’.

32 Respectively Sext. Emp. Pyr. 2.243, trans. Annas and Barnes; and Sext. Emp. Math. 10.347 = fr. 126 Döring, trans. Bury, with minor changes.

33 Sext. Emp. Math. 10.350.

34 Sext. Emp. Math. 9.209. The same argument is found at Diog. Laert. 9.98, recorded likewise immediately before the argument against causes based on the corporeal/incorporeal dichotomy (οὔτε γὰρ γένεσις οὔτε ϕθορὰ οὔτ᾽ ἄλλο τι· οὐκ ἄρ᾽ ἐστὶν αἴτιον).

35 Generation/coming-to-be and causes are, of course, conceptually related (Hankinson [n. 2], 273, in his note on this testimony of Galen, points to Arist. Gen. corr. 1.3.318a1 ff. and Ph. 1.8.191a23 ff. for discussion of their general links), but something more than this seems to be suggested by Galen's comments. Some concrete reason why Herophilus should have been particularly worried about generation in the context of his doubts about causes is called for, one which is amply provided by the thesis that Diodorus actually directed his arguments against generation against causes as well.

36 Sedley (n. 7).

37 Epict. Diss. 2.19.9.

38 As noted by Sedley (n. 7), 78, in regard to certain arguments, such as the Sorites, which were employed by Diodorus but reliably attributed to his predecessor Eubulides: ‘Some of these came to be as closely associated with Diodorus as with Eubulides, and for this reason I shall assume, wherever one of Eubulides’ riddles has passed to the Hellenistic philosophers, that Diodorus is the main vehicle of transmission …. In instances like this Diodorus' importance lies not in originality … but in his ability to impress ideas upon his contemporaries.'

39 Diodorus' arguments certainly had an impact on written works of the period: we have seen above (n. 9), for example, a response by Callimachus; his Master Argument was treated in detail in books by Cleanthes, Chrysippus, and Archedemus (Epict. Diss. 2.19.9); and Sedley (n. 7), 80–1, speculates that various arguments may have been recorded by his pupil Philo.

40 Gal. CP 198 (p. 146 Hankinson) = T59a von Staden: causa vero, utrum sit vel non, natura quidem non est invenibile.

41 Gal. CP 162 (p. 128 Hankinson) = T58 von Staden: quidam autem [sc. causam] ex suppositione acceperunt, sicut Erophilus (‘some people, such as Herophilus, have accepted [cause] ex hypothesi [only]’).

42 See e.g. Arist. An. post. 1.10.76b23–32, and Top. 1.18.108b12–19, where an endoxon can be used as the basis for arguments ἐξ ὑποθέσεως.

43 Gal. CP 198 (p. 146 Hankinson) = T59a von Staden.

44 Hankinson takes the heating, cooling, and repletion to be effects, rather than causes, the point being that Herophilus thinks it impossible to be certain about what is causing the cooling, heating, and being filled: see Hankinson (n. 2), 273, in particular where he suggests that ‘We should perhaps then supply “by something or other” after “infrigidari, estuari”, which would put them on all fours with the case of repletion. The sense then would be that Herophilus can know subjectively that he is being warmed; but it is only on the basis of a fallible causal conjecture that he can ascribe that warming to the sun's heat’; see also Hankinson (n. 5), 209–10. But there is no sign in the formulation that there is any doubt that the repletion is due to the food and drink.

45 Cf. esp. CP 36–7 (pp. 80–2 Hankinson), 96 (p. 102), 102–04 (pp. 104–6), 187 (p. 142), 192 (p. 144), 195 (p. 144); also 8 (p. 72), 11 (p. 72), 16 (p. 74), 22 (p. 76), 39 (p. 82), 42–4 (p. 84), 54 (p. 88), 74 (pp. 94–6), 100–1 (p. 104), 122 (p. 112), 124 (pp. 112–14), 126 (p. 114), 143 (p. 120), 153 (p. 124), 155 (p. 126), 168 (pp. 130–2), 173–6 (pp. 134–6).

46 On excess, see Sor. Gyn. 3.3.4 = T193 von Staden: καὶ Ἡρόϕιλος ἐν τῷ Μαιωτικῷ ϕησι τὴν ὑστέραν … ὑπὸ τῶν αὐτῶν αἰτίων νοσοποιεῖσθαι, καθάπερ πλήθους, πάχους, διαϕορᾶς τῶν ὁμοίων. On bodily liquids, see ps.-Gal. Int. 9 [14.698–9 K.] = T130 von Staden, and Celsus, Med. 1.pref.14–15 = T133 von Staden. We are not well informed on Herophilus' views on disease causation, but the importance of indigestion and corruption of food as a direct cause of disease is noted by Cael. Aur. Cel. Pass. 2.39.225 = T214 von Staden. Similarly, the Herophilean Aristoxenus points to corruption and excess of liquid in hydrophobia at Cael. Aur. Cel. Pass. 3.16.134 = Ar. 6 von Staden.

47 Von Staden (n. 1). Edition and German translation of Qustā ibn Lūqā's work in Daiber, H., Aetius Arabus: die Vorsokratiker in arabischer Überlieferung (Wiesbaden, 1980)Google Scholar, with the text and translation of the relevant passage (ps.-Plut. 5.30.1) at pp. 246–7. For the role of the Arabic version in the reconstruction of the Aëtian Placita, see Mansfeld, J. and Runia, D., Aetiana: The Method and Intellectual Context of a Doxographer, Vol. I: The Sources (Leiden, 1997), 152–61Google Scholar.

48 In Daiber's translation (n. 47), 247: ‘Herophilus glaubte: die Krankheiten werden entweder infolge der Ursache, welche “dadurch” genannt wird, durch das übermaß an Wärme oder Kälte’, etc.

49 The case of Stobaeus is not straightforward, however, since he actually separates the second part of the doxa from the first, and attributes both independently to Alcmaeon: in fact, the part which comes first in ps.-Plut. is found in Stobaeus at Ecl. 4.37.2, while the part I regard as Herophilean comes a little way before this, at Ecl. 4.36.29. This separation obviously underscores the distinct nature of the two views reported. A further source for ps.-Plut., Michael Psellus, likewise fails to mention Herophilus at his corresponding passage at Solut. Div. Quaest. (Boissonade, J.F. [ed.], Michael Psellus: De operatione daemonum [Nuremberg, 1938Google Scholar; repr. Amsterdam, 1964], p. 66), but this can tell us nothing about which authorities were referred to in his source text, since he does not mention Alcmaeon either and generally removes name labels in taking over material from the Placita: see Mansfeld and Runia (n. 47), 170.

50 Moreover, there are suggestive similarities with the general theory of disease aetiology proposed by Erasistratus, Herophilus' younger contemporary in Alexandria, who likewise thought that a major cause of disease was excess of food. Indeed, Erasistratus' views on this subject are reported in the Aëtian Placita shortly after the Herophilean doxa, at ps.-Plut. Plac. 5.30.3 = Erasistratus fr. 168 Garofalo: Ἐρασίστρατος τὰς νόσους διὰ πλῆθος τροϕῆς καὶ ἀπεψίας καὶ ϕθοράν (‘Erasistratus thought that diseases are caused by excess of food, indigestions, and corruption’). The role of excess (πληθώρα) in his disease aetiology is confirmed by Sor. Gyn. 3.4 = Erasistratus fr. 60 Garofalo and Gal. Ven. Sect. Er. Rom. 8 [11.236–240 K.] = fr. 162 Garofalo. I do not understand why D. Runia, ‘The Placita ascribed to doctors in Aëtius’ doxography on physics', in van der Eijk, P. J. (ed.), Ancient Histories of Medicine (Leiden, Boston, MA, and Cologne, 1999), 189250Google Scholar, at 250, claims that the ‘contents of the second part of the doxa [i.e. the Herophilean part] … clearly represent an earlier stage of medical knowledge than we find in the Alexandrians’. See also Allen (n. 13), who argues persuasively that Erasistratus did in fact acknowledge a causal role for such factors as excess of food, or heat and cold, despite Galen's statements in On Antecedent Causes to the contrary.

51 I am grateful to Oliver Overwien for this observation. See also Mansfeld and Runia (n. 47), 157: ‘Daiber suggests ad loc. that a Randnotiz has crept into the text and suggests no drastic conclusions should be drawn. This is surely somewhat precipitate, since the text gives a double account of both disease and health. The texts in Diels and Mau are a mess. If we accept the text in P [i.e. ps.-Plutarch], as given by Mau, then this would weigh against Q [i.e. Qustā ibn Lūqā], since Herophilus is known to have rejected the notion of causes. But at T59a Von Staden … and 59b … he does admit provisional causes, and the examples given in the former text amount to the first two causes in P.’

52 See von Staden (n. 1), 115–24; Tieleman, T., ‘Dialectic and science: Galen, Herophilus and Aristotle on phenomena’, in van der Eijk, P.J., Horstmanshoff, H.F.J., and Schrijvers, P.H. (edd.), Ancient Medicine in its Socio-cultural Context, vol. 2 (Amsterdam and Atlanta, GA, 1995), 487–95Google Scholar; Tieleman, T., Galen and Chrysippus on the Soul (Leiden, New York and Cologne, 1996), 22–3CrossRefGoogle Scholar and n. 63. Frede, M., ‘An anti-Aristotelian point of method in three rationalist doctors’, in Morison, B. and Ierodiakonou, K. (edd.), Episteme, etc.: Essays in Honour of Jonathan Barnes (Oxford, 2011), 115–37CrossRefGoogle Scholar, shows that Herophilus' well-known dictum ‘Let the phaenomena be called first things, even if they are not first things’ (T50a–b von Staden) constrains the doctor, qua doctor, to inquire into the human body at the level of perception, and not to analyse it at a subsensible or elemental level. Frede further argues that this represents an anti-Aristotelian point of method. There is not space to go into the issue here, but I would argue that Herophilus' position is fully consistent with, and probably inspired by, Aristotle's views on the kinds of principles appropriate to the practical art of medicine and their relation to the principles of natural philosophy. On Aristotle's views, see P.J. van der Eijk, ‘Aristotle on “distinguished physicians” and on the medical significance of dreams’, in van der Eijk et al. (this note), 447–59.

53 This later schema is, of course, the one that Galen is working with in CP; on it, see e.g. Hankinson, R.J., ‘Evidence, externality and antecedence: inquiries into later Greek causal concepts’, Phronesis 32 (1987), 80100CrossRefGoogle Scholar.

54 See e.g. Arist. [Pr.] 1.1–3, 859a1–24. See also D. Manetti, ‘“Aristotle” and the role of doxography in the Anonymus Londiniensis (PBrLibr inv. 137)’, in P.J. van der Eijk (n. 50), 95–141, at 125–8.

55 Cf. Diog. Laert. 9.91 for the Sceptics' direct attack on what they characterize as the Dogmatic procedure of accepting premises ἐξ ὑποθέσεως; Agrippa's fourth mode (Sext. Emp. Pyr. 1.168; Diog. Laert. 9.89); and Sext. Emp. Math. 3.1–17, attacking the use of ὑποθέσεις in the hands of mathematicians in particular.

56 See e.g. Fraser, P.M., Ptolemaic Alexandria, Vol. 1: Text (Oxford, 1972), 481Google Scholar, ‘The hedonistic doctrines of [Theodorus and Hegesias of Cyrene] are recorded in detail by Diogenes Laertius, but it does not seem likely that they were of any great significance in the intellectual history of Alexandria itself. Nor can greater importance be attached to Diodorus “Cronus”.’

57 See above, n. 51.