Bryn Mawr Classical Review

BMCR 2019.09.18 on the BMCR blog

Bryn Mawr Classical Review 2019.09.18

Massimo Catapano, Sesto empirico e i tropi della sospensione del giudizio. Lexis ancient philosophy, XIII.   Amsterdam:  Adolf M. Hakkert, 2018.  Pp. 279.  ISBN 9789025613372.  €60,00 (pb).  

Reviewed by Stéphane Marchand, Université Paris 1 Panthéon-Sorbonne (

The so-called modes of suspension are among the most fascinating weapons found in ancient Pyrrhonism. The modes (tropoi or (topoi) are arguments or sets of arguments by means of which the Pyrrhonist can challenge every dogmatic claim and attain suspension of judgment (epochē). There are several sets of modes: following the order found in Sextus (PH I.36-186), they are the Ten Modes of Aenesidemus, the Five Modes of Agrippa, the Two Modes, and the Eight Modes against the aetiologists (which are also ascribed to Aenesidemus). Amongst the many philosophical issues raised by the various sets of modes, two are of particular interest: how the modes from the same set work with each other so as to lead to suspension, and how each set of modes is connected with the others.

The present book by Massimo Catapano—which is based on a doctoral dissertation defended at the University of Rome in 2017—engages with those two issues. After advocating an “urbane” reading of the Pyrrhonian tradition, according to which the epochē promoted by the Pyrrhonists concerns only theoretical beliefs (Chapter 1), Catapano devotes a chapter to each set of modes. His attempt to offer a logical reconstruction of the line of reasoning of the modes makes him modify the order proposed by Sextus: Chapter 2 deals with the Ten Modes, Chapter 3 with the Eight Modes, Chapter 4 with the Five Modes, and Chapter 5 with the Two Modes. Actually, Sextus himself seems not to be very convinced by his own order of exposition. Also, he confesses that the arguments of the “older sceptics”—that is Aenesidemus—may be unsound (see PH I.35). Furthermore, he gives no clear explanation of the links between those sets. For that very reason, Catapano’s project to reconstruct the overall logic of the modes is audacious and interesting. His reading is always based on the texts and he is aware of the historical difficulties faced by such a project. Also, his book keeps a good balance between historical and philosophical requirements.

According to Catapano, the disorganised material provided by Sextus in book I of the Outlines of Pyrrhonism can be unified into a coherent strategy for defeating every kind of dogmatic knowledge. The modes can work together: they provide a kind of “teamwork” (cf. e.g. p. 128). Let’s begin with the Ten Modes. As is well known, they underline the relativity of our knowledge: the discrepancies among the phainomena (because of the differences that affect the subject and/or the object of judgment) show that we have only partial and relative views on things. To those who intend to grasp the nature of reality, the Ten Modes can provide various reasons to doubt that their views on things are correct. Thus, the relevance of those modes is limited to a realist conception of knowledge (see e.g. p. 84). There is nothing really new in this reading of the Ten Modes, nor in Catapano’s meticulous analysis of each one of them. Like Annas and Barnes, 1 Catapano finds those arguments frequently weak and incomplete. Sextus himself seems to agree, given that he often appeals to the Modes of Agrippa to complete the line of argument initiated by the Ten Modes.

Since Aenesidemus is also the author of the Eight Modes against the aetiologists, Catapano quite rightly chooses to treat them after the Ten. It is hard to understand the link between those two sets of modes and none of our sources gives any hint in this respect. Catapano accepts the proposal of Powers:2 it is possible that the Eight Modes come into play when the Dogmatist tries to respond to the Ten Modes by showing that he is making a justified inference from the appearance of an object to its nature because there is a causal explanation that leads from the nature of the object to its appearance (see pp. 152 and 247). Thus, the Eight Modes can be seen as an auxiliary of the Ten Modes in the same way as an Agrippan mode can be used to go from the opposition produced by the Ten Modes to epochē.

Like other recent scholars, Catapano seems much more interested in the strategy of the Sceptics who propose the Five and the Two Modes. He emphasizes the fact that the Five Modes are not a substitute for the tropes of Aenesidemus (p. 171). Rather, the Five Modes add a new line of argument, far more general and efficient because they challenge every attempt to provide epistemic justification. Aenesidemus’ Ten Modes were tailored to work against a realist conception of knowledge that was assumed by almost all ancient philosophers. But Dogmatists could answer the relativistic objection by arguing that there is some point of view or appearance that is justified and hence that is to be preferred over the others. Then the Five Modes come into action and show that no justification can be attained. There has been some discussion about whether the Five Modes are really five, or rather four or even three. Modern scholars frequently speak of the ‘Agrippan trilemma’. In line with his thesis of the strategic unity of all the tropes, Catapano claims that the Five Modes include a summary of the Ten tropes of Aenesidemus (by means of the modes of relativity and diaphōnia) and the trilemma (the modes of infinite regress, hypothesis, and reciprocity). Thus, the Five Modes do not refer only to the trilemma strategy, but rather to the reasoning that leads from the phenomenon of relativity to the impossibility of justification (p. 184).3 This interpretation is supported by the fact that, when Sextus expounds the Ten Modes, he makes use of the tropes of Agrippa. Thus, there is a link between the Ten and the Five Modes, at least according to Sextus and Catapano: the trilemma comes to the rescue of the Ten Modes when things get more complicated, as it were (p. 221). Catapano rightly emphasizes that this new strategy is not only more abstract, but also more powerful since this attack does not rely on a narrow conception of knowledge (as do the Ten Modes) and is effective against any foundationalist conception of knowledge.4

Lastly, the Two Modes: let’s imagine that an obstinate Dogmatist rejects the mode of hypothesis, for example by arguing that one can establish the truth of a hypothetical claim by showing that it accords with the criterion of truth. An Epicurean, for example, could escape the trilemma by showing that his knowledge is grounded on the truth of sensation. Then, the Two Modes operate at a different level from the Five. The Five Modes challenge first-level knowledge, knowledge of the nature or qualities of a thing; the Two Modes tackle second-level knowledge, knowledge of the criterion of truth and of a foundationalist theory. Against this kind of knowledge, the Two Modes show that knowledge itself ought to be justified either by itself (which is by hypothesis impossible) or by something else (which brings us back to the infinity regress, or the diallelus).

As regards each particular Mode, the book often provides an accurate and detailed analysis. The pages on the Ten Modes are a little disappointing inasmuch as they offer a mere description of each trope without providing an account of Aenesidemus’ overall sceptical strategy.5 Even if Catapano also takes into account the versions of Aenesidemus’ Modes in Philo and Diogenes Laertius, he does not really pay attention to what seems to be a kind of relativistic scepticism and endorses Sextus’ view that the Modes of the “ancient sceptics” are incomplete. The same could be said for the Eight tropes, despite the good pages (134-48) devoted to the relation between the critique of the causal explanations and medical empiricism. In any case, we must admit that the overall strategy of the Eight modes is not very clear in Sextus’ text, which is unfortunately our only source for those Modes.6 Hence, it is possible that an accurate understanding of those two sets of Modes and of Aenesidemus’ overall strategy eludes us.

Catapano’s discussion of the Five Modes – and in particular of the trilemma – provides a detailed analysis. Scholars have consistently emphasized the Aristotelian pedigree of the Five Modes, but Catapano digs deeper than usual in this direction, and shows interesting results. For the infinite regress, for instance, he shows (pace Barnes 1990) that this argument can be sound because that mode rests on a conception of knowledge according to which the premise ought to be known better than the conclusion, and for that reason one cannot escape this Mode by choosing arbitrarily a first knowledge-claim to begin the demonstration (p. 197). As for the diallelus, Catapano convincingly describes the foundationalist conception of knowledge underlying the modes and the ad hominem strategy of this attack. Moreover, this interpretation fits well with Catapano’s overall project to give an “urbane” interpretation of the tropes: even if some arguments – such as the Five Modes – could overturn almost all kinds of beliefs, the strategy here described seems to be more appropriate against epistemic or scientific beliefs grounded on a foundationalist conception of knowledge.

Catapano’s interpretation gives rise to at least two questions. First, who is the Pyrrhonian philosopher behind his reconstruction? Clearly, Sextus is the main target of the book; but even if Catapano’s interpretation is supported with numerous references to Sextus’ texts, Sextus himself never gives a clear picture of the unitary strategy described by Catapano. On the contrary, Sextus clearly distinguishes various types of tropes in PH I. Certainly, the various sets of modes can collaborate from a logical point of view, but Sextus insists on separating them. Hence who is the author of the “unitary strategy” that uses this web of arguments consisting of four sets of modes? And why would Sextus have given us all the pieces of puzzle without explaining how they fit together?

Secondly, if this reading gives philosophical sense to the sequence of all the modes, does it follow that each set is incomplete and insufficient? For instance, did Aenesidemus fail to notice the alleged weakness of his relativistic arguments? Such a hypothesis seems to me uncharitable; and various attempts have been proposed to make sense of his position that can also be found in DL and in Philo’s De ebrietate.7 Again, can anyone escape to the Agrippan infinite regress mode by arguing that his claim is grounded on a criterion of truth, since according to Catapano this is the dialectical move that justifies the Two modes? It is true that Sextus himself takes the example of the criterion when expounding the two modes. But that is also the case when Sextus describes the Agrippan trilemma (PH I.170). Note also that it is difficult to distinguish between the Five and the Two modes since they are drawn on the same canvas. For that reason, even if Catapano’s reconstruction is appealing and often well argued, I wonder whether the Two modes are not rather a simplification or a more economic version of the Five, since one can use the Two modes at the same level as the Five modes. Finally, the question raised by this book is the following: can the various sets of modes be at the same time a logical sequence of arguments organised in a unitary strategy and the trace of different strategies in the history of Pyrrhonism?

In sum, the reconstruction offered by Catapano is patient, full of accurate references. Despite the technical aspect of the topic, the presentation is often pedagogical and always clear. For this reason, this book is highly recommended to those interested either in the history of ancient Pyrrhonism or in ancient epistemology.8


1.   Julia Annas and Jonathan Barnes, The Modes of Scepticism: Ancient Texts and Modern Interpretations (Cambridge/London: Cambridge University Press, 1985).
2.   Nathan Powers, ‘The System of the Sceptical Modes in Sextus Empiricus’, Apeiron 43 (2010): 157-72, especially 167-8.
3.   For an accurate defence of the mode of disagreement in the Agrippan strategy, see Diego E. Machuca, ‘Agrippan Pyrrhonism and the Challenge of Disagreement’, Journal of Philosophical Research 40 (2015): 23-39. Philosophy Documentation Center.
4.   For a similar analysis, see Jonathan Barnes, The Toils of Scepticism (Cambridge: Cambridge University Press, 1990).
5.   This point is intriguing. For whereas the Ten modes were a key topic for Montaigne and a big part of modern philosophy, now those modes are somehow despised: even Polito’s recent edition of Aenesidemus’ fragments and testimonies (Aenesidemus of Cnossus: Testimonia, Cambridge: Cambridge University Press, 2014) does not offer a full analysis of those arguments.
6.   Cf. Jonathan Barnes, ‘Pyrrhonism, Belief and Causation: Observations on the Scepticism of Sextus Empiricus’ in Aufstieg Und Niedergang Der Römanischen Welt, edited by W. Haase, II.36.4 (Berlin/New York: Walter de Gruyter, 1990), 2608-95, esp. 2662 sqq.
7.   See Paul Woodruff, ‘Aporetic Pyrrhonism’, Oxford Studies in Ancient Philosophy 6 (1988): 139-68 and Richard Bett, Pyrrho, His Antecedents, and His Legacy (Oxford/New York: Oxford University Press, 2000), especially the chapter on Aenesidemus.
8.   I am grateful to Diego E. Machuca for commenting on this review and correcting my English.

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