BMCR 2011.06.10

The Demands of Reason: An Essay on Pyrrhonian Scepticism

, The Demands of Reason: An Essay on Pyrrhonian Scepticism. Oxford/New York: Oxford University Press, 2010. 130. ISBN 9780199557905.

Ancient Scepticism, Academic and Pyrrhonian, played an important role in the history of ancient philosophy from the 3rd century and for more than three centuries. In recent years, Sextus Empiricus’ treatise Outlines of Pyrrhonism ( PH) has become the tour de force of Pyrrhonian Scepticism and one of the most commented upon texts of ancient scholarship. As a result of the considerable developments in scholarship on Pyrrhonian Scepticism over the past two decades, several new translations of the Outlines of Pyrrhonism have appeared, starting with an edition by J. Annas and J. Barnes (1994, reprinted 2000), which is accompanied by an outstanding introduction. This was followed by another translation and commentary by B. Mates (1996).1

Casey Perin is well known for his work on ancient Scepticism and especially his interest in Pyrrhonian Scepticism and the problem of the Sceptic’s belief.2 In The Demands of Reason, he chooses not to offer a new translation, but rather follows the Annas-Barnes translation in order to address many of the key issues that arise from the text. He clarifies his aim as intending “to examine those aspects of scepticism – its commitment to the search of truth and to certain principles of rationality, its scope, and its consequences for action and agency – that seem to me at least to be of special philosophical significance”. He succeeds admirably in achieving this aim. The book is informative and thought-provoking from start to finish, and the answers Perin gives to the many problems of Pyrrhonism are always illuminating, although they will not always be universally accepted. Additionally, certain discussions such as those on the problem of belief and the suspension of judgement show that Pyrrhonian Scepticism is still relevant to the contemporary reader.

Perin’s main thesis is developed against the view, predominantly advocated by Gisela Striker, that reads Pyrrhonian Scepticism, or at least the version of it found in the Outlines of Pyrrhonism, as a form of anti-rationalism.3 According to this view, in the Outlines of Pyrrhonism the Sceptic ceases searching the truth once she has realised that tranquillity is a result of suspension of judgement. Such a reading appears to exclude the important role that reason plays within the process of Sceptical inquiry. On Perin’s interpretation, reason has a crucial role to play in the claim that one suspends judgement in all matters. This is because the process of suspension is largely guided by the need to “satisfy” the demands of reason. He says “the Sceptic suspends judgement when he does because, as it appears to him, reason requires him to do so. The Sceptic’s suspension of judgement is therefore guided by reason” (127).

The book is divided into a short introduction, four chapters and a short conclusion. In the preliminary discussion the author sets out the scope and limitations of the book. In Chapter 1 “The search for Truth” the focus is on the character and the aim of sceptical investigation. Chapter 2, “Necessity and Rationality” reveals the details of Perin’s interpretation of the character of the Sceptic’s suspension of judgement. In chapter 3, “The Scope of Scepticism”, the author addresses the most controversial and discussed topic in the recent scholarship – the Sceptic’s beliefs. Chapter 4, “Appearances and Actions”, deals with the equally controversial topic of appearances and action. In the conclusion, Perin raises many of the objections of the anti-rationalist interpretation, for example the conception of scepticism as therapy, unfolding his main thesis for the demands of reason once again.

Chapter 1 begins with some well known passages from the Outlines of Pyrrhonism ( PH 1.7, 1.11-3) in which Sextus shows that the sceptical way of life as described in PH 1.16-17 is part of a life of philosophical investigation. This is in direct contrast to the way of life of the dogmatic philosopher. A correct understanding of the philosophical investigation shows that the Sceptics, in a true philosophical fashion, are in search of truth and that this is not in conflict with the aim of tranquillity. For Perin the Sceptic has an interest in seeking truth both for its own sake, and as a means to achieving tranquillity. He further shows, in an elegant manner, that the Agrippan modes ( PH 1.164-9) are not necessarily incompatible with the search for truth (29-31). “For insofar the Sceptic aims to discover the truth, he also aims to do whatever is required in order for him (or anyone else) to discover the truth…then the Sceptic aims to satisfy those rational requirements that govern the search of truth”. An objection can be raised here: that although Perin’s reading of sceptical investigation as the search of truth is the most plausible, it is also severely restricts the notion of Sceptical investigation. There are passages in which Sextus appears to have a wider conception of what sceptical investigation is. An example of this is the treatment of “truths and truth” at PH 2.80-4.

In chapter 2, “Necessity and Rationality”, the author investigates the notoriously difficult and complex character of the suspension of judgment. Contra Frede, he argues in favour for a universal suspension of judgement.4 The focus here is on the kind of necessity that Sextus refers to when he describes the suspension of judgement in this way, for example at PH 1.61, 1.78, 1.21, 1.140. He suggests that the necessity attached to the suspension of judgement is not only causal, but is also hypothetical. This view, which is based on close reading of PH 2.19 and 1.175, relies on the notion it is necessarily for both the dogmatic and the sceptical philosopher to suspend judgments if they want to satisfy even the most basic rational requirements (38-42).

In chapters 3 and 4 the focus is on the status of the Sceptic’s beliefs, and on appearances and actions. Both topics have generated much discussion in the recent scholarship. Perin addresses these issues in an orderly, insightful and intelligently argued manner. His suggestion is that the beliefs of the Sceptics are beliefs about how things appear to them and not about how things are. They seem to lack this latter kind of dogmatic belief. This suggestion is not novel, but its great advantage is its relevance for the contemporary reader, as well as the strength of Perin’s argument for it. Along the same line of interpretation, Perin deals with the famous problem of apraxia and shows why Sextus believes that beliefs about how things appear to us cannot be a guide for actions. Alternatively, he suggests, commenting on PH 1.23-4, that an explanation of the Sceptic’s action can be given in terms of appearances. Perin claims that in these passages Sextus suggests that “nature guides a human being in living her life and it does so through a human being’s natural capacities for perception and thought”. He adds that “the ordinary regimen of life includes having and satisfying certain basic desires – what Sextus calls the necessity of conditions” (94-5). Although Perin’s thesis is convincing, Sextus’ “failure” to differentiate appearance from belief makes things more complicated, as Perin himself admits. In the conclusion, Perin summarises his thesis by suggesting that “in following appearances the Sceptic is indirectly following reason: reason requires the Sceptic to follow appearances insofar as it requires him to live without beliefs” (118).

In general, Perin has produced a very valuable book. It is both an important step in scholarship on Pyrrhonian Scepticism and a good read for newcomers to the study of ancient Scepticism, since it both offers new philosophical insights on Pyrrhonian Scepticism, and addresses the contemporary scholarly debate on these issues. It is to be hoped that Perin’s book, precisely because of its thought provoking nature, will be the basis of a fresh and fruitful philosophical discussion on the subjects with which it deals.


1. Annas, J. and J. Barnes (ed. and trans.), 2000, Sextus Empiricus, Outlines of Scepticism, Cambridge: Cambridge University Press, 2nd edition; Mates, B., (trans. and commentary), 1996, The Skeptic Way: Sextus Empiricus’ Outlines of Pyrrhonism, New York: Oxford University Press.

2. Perin, C., 2006, “Pyrrhonian Scepticism and the Search for Truth,” Oxford Studies in Ancient Philosophy, 30: 337–360; Perin, C., 2010, “Scepticism and Belief”, in The Cambridge Companion to Ancient Scepticism, ed. R. Bett. Cambridge: Cambridge University Press, 145-64.

3. Striker, G., 2001, “Scepticism as a Kind of Philosophy”, Archiv für Geschichte der Philosophie 83: 113-129.

4. Frede, M., 1997, “The Sceptic’s Beliefs”, in The Original Sceptics: A Controversy, eds M. Burnyeat and M.Frede, Indianapolis: Hackett, 1-24.