Chapter 11 - Doing Things with Concepts in Sextus Empiricus

Summary

In ‘Doing Things with Concepts in Sextus Empiricus’, Richard Bett examines Sextus’ terminology in connection to his use of such strategies and highlights their inventiveness and sophistication. On the one hand, Sextus appears to agree with his dogmatic opponents insofar as he says that we need to get our concepts clear before investigating any topic. On the other hand, he often raises objections against dogmatic concepts, arguing, for instance, that they are inherently inconsistent and therefore there are no objects corresponding to such concepts or, alternatively, that even if we accept these concepts, there exists nothing real corresponding to them. It is not clear whether or how these two lines of approach can be coherently combined. Nonetheless, Sextus frequently runs the two together, and Bett enquires into his reasons for doing so. An important upshot of this study is that it leads us to consider what kinds of concepts and what sort of reflection about concepts are available to a sceptic of Sextus’ variety.

What concepts are is the subject of lively and continuing debate. Are they in our heads, and if so, what form do they take? Or are they abstract objects – Fregean senses, for example, or ‘the constituents of propositions’¹ – with which we somehow interact in our speech and thought? Do they vary from person to person? And should we draw a definite distinction between the concept of X, understood as relatively unified and stable, and various different conceptions of X, which ‘are thought to be more ephemeral and idiosyncratic than concepts’?² These are some of the many questions in this area, the answers to which may affect, or be affected by, our most basic commitments in the philosophy of mind and language. Fortunately, we need not worry about any of these deep and difficult questions, because we are dealing with Sextus Empiricus, who, as a Pyrrhonian sceptic, does not adopt philosophical theories, whether about the nature of concepts or about anything else. But these contested matters are nonetheless worth mentioning, if only to indicate that the territory we are dealing with under the heading of ‘concepts’ is somewhat indeterminate. For an author like Sextus who not only eschews theory, but also deliberately avoids what he considers over-precision in the use of language (PH. 1.207, cf. 1.17, 1.191), this is perhaps only appropriate.

There is in fact quite a lot in Sextus that can naturally be seen as addressing the topic of concepts. There are four or five relevant terms in his texts that either can be translated, in many contexts at least, by ‘concept’, or pick out items that we would generally be prepared to call concepts. To explain these terms, it will be useful, despite the emphasis I have just placed on Sextus’ avoidance of theory, to begin with a brief detour into Stoic and, to a lesser extent, Epicurean theory, since this is the historical background for Sextus’ usage (Section 1).³ Having clarified the terminology, I propose to survey the various kinds of uses Sextus makes of the notion of concept – mostly, as we shall see, in his arguments with the dogmatists on a great variety of subjects, but also in his exposition of scepticism itself (Sections 2 and 3). I will close (Section 4) with an issue that Sextus addresses, and that some of the sceptics’ opponents apparently considered a serious objection: how can a Pyrrhonian sceptic, who shuns not only knowledge but even definite belief, make use of concepts at all? Does not a repertoire of concepts itself incorporate a body of beliefs?

1 Historical Background to Sextus’ Usage

An important passage of Aëtius (4.11.1-4 = LS 39E) reports a Stoic theory of basic concept development in childhood. According to this theory, a human being at birth ‘has the leading part of the soul like a papyrus all ready for writing on’ and ‘on this writes each one of the concepts [ennoiōn]’. This occurs through the clustering together of multiple similar perceptual impressions [phantasiai]; for example, we acquire the concept of white from seeing and remembering many white objects.⁴ Concepts are thus thought of as generic impressions imprinted in the memory (Plut., Comm. not. 1084F–1085B). The anticipation of the Lockean notion of the tabula rasa is obvious, but one should not assume that this is a pure empiricism. The antecedent nature of the human being also has a role in determining which concepts do in fact develop; this is perhaps particularly obvious given the pervasiveness of teleological design in the Stoic universe, although, as the case of the Epicureans shows (more on this in a moment), the idea that our natures prepare us to develop certain concepts and not others is not essentially dependent on a teleological picture. Aëtius draws a further distinction between concepts that develop simply by nature, with no intervention from other human beings, and those that develop through human instruction; while the term ennoia covers both categories, the former group, he says, are also called prolēpseis, usually translated ‘preconceptions’.⁵ Now, the Epicureans also use this term ‘preconception’ – indeed, Epicurus seems to have invented it (e.g., RS 37, 38) – and in essentially the same way; in Epicureanism, according to Diogenes Laertius, it is ‘a sort of apprehension or correct opinion or concept [ennoian] or universal thought stored away inside, that is, a memory of what has often been revealed externally, for example ‘This is a human being’; for as soon as ‘human being’ is said, its shape is thought of in virtue of preconception’ (Diog. Laert. 10.33, cf. 31). Preconception is identified as one of the Epicurean criteria of truth (Diog. Laert. 10.31), and in what appears to be an explanation of this point – though the word prolēpsis itself is not used – Epicurus speaks of the need to have a clear concept of what you are talking about in order to conduct any inquiry (Letter to Herodotus, Diog. Laert. 10.37).⁶

The word for ‘concept’ in this last passage is one we have not yet considered, namely ennoēma. And the Stoics too have a use for this term; the Aëtius passage I referred to before continues by talking about this. Aëtius says, somewhat unhelpfully, that ennoēma is ‘a figment of thought of a rational animal’ (4.11.4 = LS30j). The talk of ‘figment’ (phantasma) is repeated elsewhere (Stobaeus 1.136,21–137,6; Diog. Laert. 7.61), and has to do with the Stoics’ denial of the reality of universals, which are regarded as ‘not-somethings’.⁷ But the grammatical relation of ennoēma to ennoia – the former being, most literally, a ‘thing thought’, while the latter, sometimes at least, is an ‘act of thinking’⁸ – implies that the former should be thought of as the intentional object of the latter, and the evidence, though not really explicit, seems to suggest that this is the case.⁹ If so, then in Stoicism too ennoēma can naturally be translated ‘concept’, with a leaning towards the abstract, Fregean-sense-type understanding of what concepts are. There are notorious difficulties in understanding Stoic ontology at this point; most obviously, how can something that is repeatedly singled out as non-existent play an important explanatory role?¹⁰ But for the present purpose, we need not concern ourselves with this can of worms; as the much more straightforward usage of Epicurus confirms, the word itself need not be so metaphysically freighted.

Besides, as it happens, ennoēma is very rare in Sextus. It occurs in only two places: one where he is clearly referring to the Stoic view (PH2.219, cf. Diog. Laert. 7.60), and another where he is considering a dogmatic attempt to respond to an argument to the effect that wholes can be neither distinct from nor identical with their parts (M. 9.355–6).¹¹ The attempted response seems to depend on the idea that whole and part are mere human classifications and do not answer to anything objectively out there in the world. As a result, there is talk of the concept of a whole human being and concepts of the parts of a human being, in contradistinction to the human being and the parts themselves; but it can hardly be said that concepts are a main focus of the discussion. It is, however, worth noting that ennoēma and ennoia seem to be used in this passage interchangeably; Sextus speaks of the ennoiai of the parts, and then immediately afterwards of the ennoēma of the whole (M. 9.355), with no apparent distinction intended between them. Sextus would probably describe this as a case of his lack of concern for fine linguistic distinctions; but if my account in the previous paragraph of the relation between ennoia and ennoēma was on the right lines, he is actually skating over an important element in the dogmatists’ theories of concepts and concept formation. However, since these theories do not themselves feature among the topics he addresses in his writings, we need not be too troubled about his lack of attention to these details.

The other two terms we have looked at so far, ennoia and prolēpsis, are both common in Sextus. Again, he does not preserve the Stoic distinction between the two. He would have had no interest in trying to demarcate concepts acquired by nature alone from those acquired through instruction, and indeed in one place he speaks of prolēpsis in a specifically cultural context; each person, he says, will respond to the appalling demands of a tyrant in terms of ‘the preconception that accords with his ancestral laws and customs’ (M. 11.166). As one might expect of a sceptic, his usage of prolēpsis also diverges from that of both the Stoics and the Epicureans in that it does not have a built-in presumption of correctness;¹² hence he can speak of people having conflicting ‘preconceptions’ (M. 9.61, M. 1.53) or misguided ones (M. 11.129). But still, it is because of the history of this term in Stoicism and Epicureanism that Sextus can often use prolēpsis, ‘preconception’, in contexts where what he is talking about is clearly something that we would want to call a concept.

There are some cases where Sextus’ use of the term is looser still, and it seems as if the point at issue is not a conceptual one at all; and the same is also occasionally true of ennoia. For example, in Against the Physicists he says that ‘the common preconception of ordinary life’ says that there are gods (M. 9.50), which looks like a pure existence claim rather than anything to do with the concept of god. This is continued with a reference to ‘the common ennoia’ concerning god, which is immediately glossed as people ‘believing in common that there is something divine’ (M. 9.61). (Of course, some people have thought that the existence of God could be inferred from the concept, but there is no hint of that here.) And a little later he speaks of ‘the common ennoia’, and then, ‘the prolēpsis’, ‘about the things imagined to go on in Hades’ (M. 9.66, 74), which again seems to be referring to beliefs rather than concepts. But the division between what is conceptual and what has to do with belief is not a sharp one, and what might at first seem to concern only belief can often be construed as conceptual without much trouble.¹³

The tyrant case mentioned a moment ago is a good example: while the ‘preconception’ in question could be read as something purely propositional, such as ‘tyrants who make appalling demands must be resisted [or, must be accommodated]’, it could also be read as the concept noble, which is understood to include resisting outrageous exercises of authority, or as the concept prudent, understood to include not getting on the wrong side of someone with absolute power.¹⁴ It should be noted that if we adopt this approach, the amount of content that is taken to be built into concepts will turn out to vary a good deal. For example, at one point in Against the Ethicists Sextus says that there is a common prolēpsis of the good as that which attracts and benefits us, but that there is wide disagreement about what things are good (M. 11.44); but then, having illustrated this disagreement, he sums it up by saying that there is disagreement precisely in the prolēpsis of good (M. 11.68).¹⁵ This is perhaps a little confusing, but it simply illustrates a flexibility in how much is to count as built into the concept.

Besides ennoia and prolēpsis, Sextus also frequently uses epinoia, apparently as equivalent to ennoia. Finally, there is noēsis, which can also best be translated ‘concept’ in many cases, although again not all; sometimes, as the –sis suffix would suggest, it is better understood to refer to the act or process of conceiving something (e.g., M. 8.88, M. 3.43, 48), and sometimes noēsis is contrasted with aesthēsis, ‘sense-perception’, standing for the faculty of intellect (e.g., M. 7.217, 355–6, M. 11.88).

So much for the terminology. What does Sextus do with it?

2 Sextus’ Treatment of the Notion of Concept: Overview

The answer is: a number of different things. I have already mentioned a few appeals on Sextus’ part to preconceptions common to humanity. And although, as we saw, these are sometimes not readily understood as conceptual in nature, there are numerous other cases where a ‘common ennoia’, or a ‘common prolēpsis’, clearly is a concept that is supposed to be shared by everyone. The arguments concerning the existence of god in Against the Physicists are again a good example – this time on the negative side. At several points Sextus appeals to something about the common concept of god, as he construes it, as part of an argument against the existence of the divine. For example, the common concept of god includes god’s being an animal (M. 9.138); but being an animal carries with it the possession of senses, which in turn entails susceptibility to outside influences, including unpleasant experiences and thereby changes for the worse. But a being of that kind is surely perishable, and hence not divine – because perishability itself would go against the common concept of god (M. 9.143). Again, it would go against common concepts of god (koinais ennoiais, M. 9.178 – the plural here is an interesting variation) to deny that god has speech. But speech surely requires bodily organs such as windpipe and lungs, which do not befit the divine; there are also problems concerning the language in which god is supposed to communicate (M. 9.179). While the overall purpose is to argue that god does not exist (with this to be balanced against a series of previous arguments for god’s existence), the appeals to the common concept can occur, as we have seen, at either end or both ends of the arguments: a necessary feature of god (according to this common concept) can be set up at the start – a feature that is then shown to be impossible – or a necessary feature of god can be invoked to drive home the conclusion, when a certain result is said to be incompatible with this feature, and hence to rule out the existence of divinity.

A similar, though slightly less direct, move is made in Against the Geometers. Sextus has been considering the geometers’ definition of the line as a ‘breadthless length’. His general approach is to argue that it is impossible to make sense of the idea of anything having length without that thing also having some breadth. Appeals to inconceivability are fairly common in this book, including on the topic of the line, and we shall return to this point in the next section; but they do not generally take the form of a confrontation with a concept shared by all humans. At one point, however, having mentioned an attempt to save this definition of the line by describing a thought-process in which the breadth of something is gradually whittled away until there is no breadth remaining, but only length, Sextus retorts that one might as well try to imagine flesh with its vulnerability wholly removed, or body with its resistance entirely stripped away; and this, he says, ‘is completely impossible and goes against the common concept of humanity’ (M. 3.56). The common concept is not specifically that of the line, but that of a vulnerable, flesh-and-blood body; but our reflexive endorsement of this common concept, and of what it excludes, is intended to nudge us towards an analogous rejection of the idea of a length without breadth.

A somewhat different case occurs in the arguments against motion in Against the Physicists.¹⁶ Having set out the argument against motion of Diodorus Cronus (M. 10.85–90), Sextus mentions some objections to it, one of them being that it contradicts the concept of motion (M. 10.94). The word ‘common’ does not appear, but it seems clear that an everyday concept of motion is being appealed to. However, in this case the appeal to common concepts is not on behalf of the line of argument that Sextus is pursuing, but against it. And this is reinforced when he returns to the point about Diodorus violating the concept of motion, and replies that even if we accept the conceptual point, the real question at issue is whether motion exists – and the fact that an argument for motion’s non-existence conflicts with the concept of motion does nothing to show that the conclusion is not true (M. 10.105–6).

So Sextus will sometimes appeal to shared concepts in order to advance his own line of argument; but he is also capable of resisting such appeals when they threaten to oppose the argument he is conducting. There is nothing wrong with this; given the sceptical method of assembling equally powerful opposing positions, with a view to suspension of judgement, any line of argument he is conducting at any given time is only provisional and eventually to be balanced by countervailing considerations. There are no fixed assumptions about what is or is not a legitimate argumentative practice; the only question is what will serve as persuasive on a specific occasion. But we find a similar bifurcation of approach concerning the common concepts of humanity at a meta-level, so to speak, and this may be more problematic.

Sextus sometimes likes to present himself as on the side of ordinary life, and the dogmatists, with their theoretical abstractions, as in conflict with it. Perhaps the best example of this is in his treatment of signs – that is, means for inferring from the observed to the unobserved – to which he gives considerable attention (PH2.97–133, M. 8.141–299). He distinguishes between recollective signs and indicative signs. The former are observable phenomena that allow one to infer the existence of other things that are not currently observable, but that one has observed in the past in correlation with the things currently being observed (whose existence is thus brought to mind through the memory of these past correlations); Sextus’ favorite example is observed smoke as a sign of currently concealed fire. By contrast, indicative signs are observable phenomena that are supposed to allow one to infer the existence of things that are not observable, period (at least in the state of science in Sextus’ time), such as atoms, pores in the skin, etc. Now, Sextus will have nothing to do with indicative signs, and argues at length that they are a fiction of the dogmatists (while making clear his real goal is suspension of judgement on the topic: PH2.130–1, M. 8.159–61). But he is happy to employ recollective signs, since they involve no theoretical commitments, and he declares himself and his fellow sceptics in this respect in tune with the practice of ordinary people (PH2.102, M. 8.157–8). In Against the Logicians this is expressed by saying that they are in tune, whereas the dogmatists are not, with the ‘common preconception of humanity’ (M. 8.157–8). The point, I take it, is that the ordinary concept of a sign is what Sextus calls the recollective sign, and that the dogmatists’ indicative sign is at odds with everyday concepts. He presents this as a response to an objection against scepticism, and it looks as if rebutting the suggestion that sceptics are out of step with ordinary life is of some importance to him.¹⁷

But in another place in Against the Logicians, again in reflecting on his own sceptical activity, Sextus adopts a somewhat different attitude towards common human concepts. He says that in order to create a situation in which the opposing positions on some topic are equally powerful – a necessary condition for suspension of judgement – it may be necessary to concentrate on the more counterintuitive side of the case. The other side already has a good deal of persuasiveness to it, and so as far as that side is concerned, the sceptic can ‘be content with the common preconception as a sufficient basis’ (M. 7.443). The topic is the criterion of truth, and the ‘common preconception’ in this case is presumably an everyday idea of what it is for some faculty or device to be definitely telling us the truth.¹⁸ It would scarcely be imaginable that such a concept would be prevalent in everyday life without the accompanying assumption that such criteria are in fact generally effective; and so this ‘common preconception’ will create a powerful initial presumption on the positive side of the debate on whether there is a criterion of truth, prompting the sceptic to devote more energy to the negative side. But now, since the goal is to produce suspension of judgement between the two opposing positions, it follows that Sextus is not on the side of the ‘common preconception’, as he professed to be in the case of signs. This is an issue that recurs periodically in Sextus: it is hard to see how one can both claim to be on the side of ordinary life and include ordinary concepts (or, in other cases, ordinary opinions) among the mix of opposing considerations leading to suspension of judgement on some topic. Of course, consistency is maintained if the issues on which one does the former are different from those on which one does the latter. But the point about letting the ‘common preconceptions’ do most of the work on the positive side is stated in general terms, even though it is applied to the specific case of criteria. And there are other instances where it looks as if he adopts both stances on the same topic.¹⁹

In any case, this is one major way in which concepts figure as a topic in Sextus’ works: his various appeals to everyday, shared human concepts. But often when he discusses concepts, he is thinking of something very different – namely, concepts as captured in dogmatic definitions. Sextus mentions a definition of definition itself as ‘an account bringing us through a brief reminder to a concept [ennoian] of the objects underlying the words’ (PH2.212). The same definition is cited in the pseudo-Galenic Medical Definitions (19.349,2-4K = LS 32D) alongside another that is elsewhere attested as Stoic (DL 7.60). Whether or not this one is also Stoic in origin, there is reason to think that the Stoics saw definitions as articulating the shared human concepts that we all naturally develop (cf. Cic., Tusc. 4.53, Augustine, De civ. D. 8.7) – in which case we would not be far from the territory we were just exploring. But this is not how Sextus approaches the matter; in fact, in one place he seems to be making fun of the Stoics for treating their definitions as if they had something to do with shared everyday concepts. He introduces a Stoic definition of good by saying that ‘The Stoics, holding on to common concepts, so to speak, define the good in this way’ (M. 11.22). ‘So to speak’ (hōs eipein) can hardly be a comment on the phrase ‘common concepts’ itself, since, as we have seen, it is frequent in Sextus’ own works; it must instead be a side-swipe at the Stoics for claiming to adhere to everyday concepts in their definitions.

And when Sextus himself ties concepts to dogmatic definitions, he is very clear that this is a purely theoretical matter, far removed from everyday thinking. Both in Outlines of Pyrrhonism and in Against the Logicians, the concept – that is, the dogmatic definition – of demonstration (apodeixis) is built up to by an elaborate analysis of what the dogmatists take a demonstration to be (PH. 2.135–43, M. 8.300–15). Later in Outlines he introduces a concept or dogmatic definition of the sophism (PH2.229); this is itself of course a technical notion, but Sextus specifically says that logicians bring it up ‘as a help to life, which is tossing and turning’ – in other words, as a supplement to everyday methods of speaking and thinking, which they consider (laughably, in Sextus’ view) to be wholly inadequate on their own. And when he says that he has shown us the concept of place (M. 10.6), what he has in fact done is summarise several different dogmatic definitions of place (M. 10.2–5); and shortly afterwards (M. 10.15) he explicitly distinguishes an everyday, unsophisticated conception of place from the theoretical understanding of it that is his topic of investigation.²⁰

Given this emphasis on the dogmatic character of these concepts or definitions, it comes as something of a surprise that Sextus is willing to speak, in a tone that is at first sight not dissimilar to this, of the concept of scepticism itself. The ennoia of scepticism appears on the list of topics to be covered in the overview of scepticism in the first book of Outlines of Pyrrhonism (PH1.5), and this term is twice repeated with the same reference later in the book (1.11, 1.209). And the place where he speaks of the concept is the chapter called ‘What is Scepticism?’ (1.8–10); this is clear both from the order in which the topics are dealt with and from the fact that one of the subsequent uses of the term ‘concept’ (1.11) is an immediate and direct back-reference to this chapter. The chapter begins with the well-known sentence about the sceptical ‘ability’ (dunamis): ‘The sceptical ability is one that places in opposition things that appear and things that are thought in any way whatsoever, from which, because of the equal strength in the opposing objects and accounts, we come first to suspension of judgement, but after this to tranquility’ (1.8). The rest of the chapter then explains various points about this sentence. Sextus does not actually call the quoted sentence a definition of scepticism. But this sentence is obviously telling us what scepticism is (whether or not the chapter title ‘What is Scepticism?’ is Sextus’ own²¹), and thus seems to be fulfilling the function of a definition, while the explanation that follows seems reminiscent of the explanatory material accompanying the definition of demonstration that I alluded to in the previous paragraph. Is Sextus here buying into a practice that he elsewhere seems to go out of his way to associate with the dogmatists?

In fact, I do not think he is vulnerable to this charge for at least two reasons. First, he tells us just before this that he does not claim ever to give a definitive statement of how things are; he merely reports how things appear to him at the time (PH1.4). And this applies to the account of what scepticism is as much as to anything else. Thus, although his one-sentence statement of what scepticism is has the look of a definition, it does not approach this in a dogmatic spirit; that is, it does not purport to capture scepticism’s essence, or to state the fixed necessary and sufficient conditions for an activity to count as scepticism. Second, when he says what scepticism is, he is describing, precisely, an activity. He is saying, this is our method – this is what we do. He is not telling us anything about the nature of things – as with the dogmatic concept of place, to return to one of the examples mentioned a minute ago – nor is he telling us about a device that is meant to lead us reliably to a conclusion about something unclear (adēlon), as with the dogmatic concept of demonstration. And his further explanation of the one-sentence description of scepticism, in the rest of the chapter, also focuses on what the sceptic does, filling out the various phrases in the opening sentence, but not delving into any matters of doctrine or theory, as the explanations of the dogmatic definitions of place and demonstration did. Thus, his answer to the question ‘what is scepticism?’ shows that he does not see it as even the sort of object that would admit of a definition purporting to capture a thing’s essence. And so, if Sextus is entitled to use concepts at all – and we shall return to this issue in the final section – he is entitled to speak in this rough-and-ready way about what scepticism is and to explain it as he does. Indeed, as we shall see, this case fits rather nicely with the picture he offers of how concepts are available to the sceptic.

I want to look more closely at how Sextus handles concepts as laid out in dogmatic definitions, and the next section is devoted to this topic. But first I will complete my survey of the range of things he does with concepts by touching on two other strategies of his – one relatively common, the other sui generis – both of which have to do with how concepts can arise. First, he makes repeated use of a broadly empiricist account of concept formation, according to which we gain concepts either through direct experience or by various kinds of imaginative transformations of what we experience, such as resemblance, combination, increase or diminution. Direct experience would account for our acquiring the concept of a horse, for example, while transformations would allow us to acquire the concepts of such things as centaurs, cyclopses or pygmies. Sextus employs this account in Against the Logicians (M. 8.58–60), Against the Physicists (M. 9.45, 393–5), Against the Ethicists (M. 11.250–2) and Against the Geometers (M. 3.40–2), always using closely related examples and always quoting a line or two from the Odyssey (M. 9.191–2) describing the Cyclops. He is borrowing here from the Stoics; Diogenes Laertius summarises a Stoic theory of concept formation including all the same kinds of transformations as appear in Sextus and all the same examples (7.52–3, cf. Cic., Fin. 3.33). And it looks as if the Epicureans also had a similar view (Diog. Laert. 10.32). All this is clearly connected with the Stoic and Epicurean picture of concept development that we looked at in the previous section.

Sextus’ purpose in using this account differs somewhat from passage to passage, but the general idea is to put forward these methods of concept formation as the only possible ones, and then to derive difficulties if this is granted. In Against the Physicists (M. 9.393–5) and Against the Geometers (M. 3.40–2) the point is something we encountered earlier – the inconceivability of the line as a ‘breadthless length’; there is no possible transformation of an experience that could get us to the concept of a length that has no breadth. In Against the Logicians (M. 8.58–60) the account appears in a series of conundrums concerning truth, in the course of an argument to show that if one refuses to trust the senses, as Democritus and Plato are supposed to have done, one cuts off the possibility of any concepts at all. And in Against the Ethicists (M. 11.250–2) it figures in an argument against the possibility of teaching and learning; the idea is that for teaching and learning to occur, the wise teacher must be capable of understanding the lack of wisdom, or folly, of the learner – but given the available means of concept formation, this is not possible. The latter argument, in particular, seems open to numerous objections. But in every case, the question may of course be raised as to why we should accept this theory of concept formation. Sextus’ reply would no doubt be that he does not insist on it (it is, after all, borrowed from the dogmatists), but that the onus is on anyone who does not accept it to come up with a better account that would not have the same unpalatable consequences. Some of these passages are in fact followed by attempts at alternative accounts, which are then shown to have problems of their own. In Against the Physicists and Against the Geometers, for example, the idea is floated that one might be able to conceive of a breathless length by ‘intensification’ (epitasis) of an imagined process of reducing the breadth – to which the reply is that one can reduce the breadth all one wants, but that if the breadth is removed altogether, so is the length (M. 9.403–6, M. 3.51–4). As always, the goal is not to prove the truth of the conclusions, but to make the possibilities under consideration no less persuasive than the opposing positions. And in the service of this goal, Sextus several times finds this Stoic and Epicurean view of concept formation a useful tool.

I have left aside one other occurrence of this account, in a somewhat truncated form, in Against the Physicists (M. 9.45), because this also belongs to the second additional strategy to which I wanted to draw attention. Sextus says that we might suppose we could acquire a concept of god by imaginatively augmenting various features of a successful and fortunate human being, such as happiness and length of life, so as to arrive at a blessed and eternal divine being. The problem this time is that such a process would run up against the reciprocal mode (M. 9.47): in order to conceive a happy human being, we must know what happiness is, but happiness itself – or rather, eudaimonia, which is standardly translated ‘happiness’ – already presupposes divine (daimonia) matters).²² Hence the happy human being cannot serve as the prototype for a concept of the divine. Now this is like the other passages we have just been considering in that a plausible view of concept formation is used to show that a certain particular concept cannot be (or in this case, could not have been) formed. But in this case – and this brings us to the second strategy – it is part of an extended examination of how the concept of god might have arisen (M. 9.14–48). And this, as far as I can see, is unique in Sextus. He frequently subjects concepts themselves to scrutiny (more on this shortly); but there is no other place where he looks at length at theories of how we could have come to have a concept that we do have. The point here is not to show that god cannot be conceived (as he argues in Outlines concerning the dogmatic concept of god, PH3.2–6); on the contrary, in the course of this discussion he makes use of the idea that we all have a common ‘preconception’ of god with several core features (M. 9.33). Instead, the procedure here is to lay out a series of theories concerning how this concept of god arose, and then raise difficulties for all of them. In that respect it is a classic example of the sceptical method of opposition; but in terms of the subject-matter to which the method is applied, this passage stands out.²³

3 How Sextus Deals with Concepts Featured in Dogmatic Definitions

How, then, does Sextus deal with those concepts that are delineated in dogmatic definitions? There are two ways in which he tends to approach them. In their pure forms, they are clearly distinct and easy enough to describe (as I shall begin by doing). But there are complications: they do not always occur in their pure forms, and while this is not in itself problematic, occasionally it does seem to get Sextus into some trouble.

On the one hand, Sextus can begin his discussion of a topic by a review of the dogmatic concept, taking this at face value, and then generate impasses concerning the object picked out by the concept – concerning the existence of this object, for example, or the possibility of our knowing it. In this case the review of the concept is conducted in a neutral spirit, with a view to clarifying what we are talking about, and the sceptical work comes later. Against the Rhetoricians is a good example of this on a large scale. At the start Sextus says that ‘the concept is common to existence and non-existence’ – that is, we can have a concept of something whether or not that thing exists – and that ‘it is not possible to do any investigation of either of these [i.e., of the thing’s existence or non-existence] without having formed a preconception of what it is that is being investigated’ (M. 2.1); hence he proposes first to establish the concept of rhetoric and then to consider whether there is any such thing. And this is what happens. In the opening sections he surveys three overlapping definitions of rhetoric by earlier philosophers (M. 2.2–9); and then, on the basis of a crucial feature common to all three – that rhetoric is ‘an expertise or science of words, or of speaking, and productive of persuasion’ (M. 2.9) – the rest of the book gives multiple arguments for rhetoric’s non-existence. None of the words identifying concepts that we looked at in section I appear after this point. Another example is the part of Against the Physicists on place (M. 10.1–36); Sextus opens the discussion, as noted earlier, with some dogmatic definitions of place, and then shifts to the main task in the following words: ‘Now that the concept of place has been made clear and the things connected with it have been pointed out, it is left – as is the sceptics’ habit – to advance the arguments on either side and to strengthen the suspension of judgement that is arrived at from them’ (M. 10.6).

The other approach is to subject the concepts themselves to sceptical scrutiny. A recurring pattern here is for Sextus first to create trouble for the concept, and then to argue that, even if we leave aside these problems, the object does not exist or cannot be apprehended. As I observed at the end of the previous section, the section on god in Outlines of Pyrrhonism includes arguments to the effect that the dogmatists fail to fashion a viable concept of god (PH3.2–5); and this is immediately followed by ‘Even supposing god is conceived, it is necessary to suspend judgement on whether or not there is one’ (PH3.6), and the argument turns to the latter subject. Another, somewhat more extended case occurs in Against the Logicians, where the criterion of truth, in one sense of that term, is identified as the human being (M. 7.261). Sextus then proceeds to argue first that it is impossible to arrive at a clear definition that captures the essence of the human being (as opposed to enumerating attributes) and includes all human beings and no other beings (M. 7.263–82). He makes clear that if we cannot arrive at a clear concept of the human being, that suffices to show that the human being cannot be apprehended (M. 7.263–4, 283); nevertheless, having argued for inconceivability, he continues with a series of independent arguments for inapprehensibility (M. 7.284–342). Similarly, the discussion of time in Against the Physicists begins with some dogmatic definitions of time, arguing that they are either internally incoherent or inconsistent with other basic tenets of those who proposed them – or else with basic points that all of us would accept (M. 10.170–88). This is summed up with the words ‘This, then, is how the existence of time is to be put into impasse on the basis of the concept’ (M. 10.188), and the argument then turns to other, non-conceptual arguments against its existence.²⁴

Something like this also happens earlier in Against the Physicists on the subject of motion (M. 10.50–61), except that here the inconceivability of motion follows only given certain philosophical assumptions; for those who do not share these assumptions, the concept is viable, but there is a further question concerning whether or not motion exists (M. 10.60).²⁵ This is therefore a sort of hybrid of the two approaches I have described; for some, the discussion of the concept will function as a neutral prelude to a consideration of motion’s existence, while for others, it will function as an attack on the concept.

Thus, we have already begun to see that the two approaches, though easy enough to describe separately, are in practice not always kept entirely distinct. In addition, the distinction between accepting a certain concept and accepting the reality of the things identified by that concept – which both approaches, in the forms I have described them so far, seem to presuppose – is not always preserved.²⁶ For an argument against the viability of a certain concept can also be thought of as an argument against something’s existence – indeed, this already began to emerge above. But this means that there is no necessity for the neat sequence ‘first look at the concept, then look at whether the thing conceived exists’ to be preserved in every case; and in fact, arguments concerning concepts often feature in the course of arguments concerning existence, so that the two stages in the second approach, as I first presented it, become amalgamated.

This is perhaps especially liable to happen when we are dealing with mathematical objects, which (however we may understand their ontology) are hard to discuss other than in terms of the way mathematicians conceive them – unlike, say, place or motion, which have obvious roles in our lives apart from any theory. Thus the main bulk of Against the Geometers addresses the ‘principles’ of geometry – point, line, surface and body (M. 3.19–21) and argues for their non-existence (M. 3.92); but as we have already noted, a considerable proportion of the text is occupied with challenging the geometers’ concepts of these things – the line as a ‘breadthless length’, but also, for example, body as a combination of length, breadth and depth. The same is true of the treatment of body in Against the Physicists, much of which runs along the same lines as Against the Geometers.²⁷ The conclusion to be argued for is that ‘body is nothing’ (M. 9.366, 437, 439). But almost all of the argument turns around difficulties in the concept of body as the combination of length, breadth and depth (M. 9.367–436); only at the very end, having said ‘We have now done our investigations getting to grips with the concepts of body and limits’ (M. 9.436), does he turn to a brief further argument that does not depend on these conceptual matters (M. 9.437–9). A further, less extreme example is the lengthy discussion of demonstration in Against the Logicians, which starts with what appears to be an instance of the first approach I distinguished, a neutral review of the dogmatic concept of demonstration (M. 8.300–15), and then (after another introductory section) proceeds to the question whether there is any such thing (M. 8.336), but in the course of the many arguments against the existence (or sometimes, e.g., M. 8.396–447, the apprehensibility) of demonstration includes an argument for its inconceivability (M. 8.381–90) – which is again signaled as being tantamount to showing its unreality (although showing that it was conceivable would not have been enough to show its reality) (M. 8.381).

Once again, there is nothing wrong with this mélange of approaches. Clarifying the concept and then creating problems concerning the object identified by it and attacking the very concept (whether or not one treats that as showing the object’s non-existence), are both legitimate ways to generate a sceptical outcome; and so long as one is clear which one is doing at any given time, there is no reason why they cannot be pursued alongside one another. But here is the one respect in which Sextus seems to show some confusion on this topic. I mentioned Against the Rhetoricians as a clear instance of the first kind of approach, and I quoted its opening remark about the importance of achieving a clear preconception of an object before investigating it. Now in two other places, in Against the Ethicists (M. 11.21) and Against the Grammarians (M. 1.57), he makes the same point in very similar language, in both places approvingly attributing the idea to ‘the wise Epicurus’ – who, as we saw in the first section, does indeed seem to accept it.²⁸ Yet in both cases, the discussion that follows includes at least a considerable measure of the second kind of approach. In Against the Ethicists a Stoic definition of the good is explained and then criticised, and this section is summed up by saying that ‘the dogmatists did not outline the concept of good and bad in a convincing fashion’ (M. 11.42). And in Against the Grammarians, several grammarians’ definitions of grammar are introduced and found fault with, and the section ends with a statement that is a nice example of the amalgamation of conceptual arguments and existence arguments illustrated just now: ‘Enough said, then, by way of example, towards the non-existence of grammar – as long as we go by the grammarians’ concept of it’ (M. 1.90). The rest of the book then attacks the alleged expertise of grammar on other grounds, with no further reference to concepts.

All of this leaves us rather bemused: in these two places, is Sextus clarifying the concept for purposes of investigation, or is he undermining it? His initial statements suggest the first, but his actual procedure seems to be closer to the second. We might perhaps think that he is being ironic here: ‘Yes, sure, let’s get clear on the concept; Epicurus knew what he was talking about on that score’ – which is then immediately followed, in effect, by ‘Good luck with that!’. But although Sextus is certainly capable of various kind of humor, and although I also think he is capable of a number of subtle effects through his writing,²⁹ this seems to me a step too far; it just does not seem to ring true to his usual modes of address to the reader. However, the alternatives are either that he is confused about what he is doing, perhaps through not having sufficiently distinguished the two approaches I have been discussing; or that he is clear about the difference between the two but has had a change of mind about which method to use and has not adequately revised his work so as to make it consistent. Neither reflects on him particularly well.

These lapses are rare; most of the time, as I say, the two approaches are pursued separately, or are combined in ways that seem unobjectionable. I close this section with two additional points. There was a good example of the first just now, in my quotation from Against the Grammarians: ‘Enough said, then, by way of example, towards the non-existence of grammar – as long as we go by the grammarians’ concept of it’ (M. 1.90). The explicit allusion to the grammarians’ concept of grammar makes obvious sense in the context. But it also gives him another way to keep his conclusions provisional and avoid seeming to endorse them dogmatically. If a certain conclusion applies given a concept that has been put up for discussion, this leaves open the possibility that there might be other relevant concepts that would not have the same result. And this kind of remark occurs in a few other places as well. In Outlines of Pyrrhonism he introduces the topic of body with a definition: ‘Some say that body is what can act or be affected’ (PH3.38). And he immediately continues with ‘But as far as this concept is concerned [hoson epi tautēi tēi epinoiai] this is inapprehensible’. And a little later, having considered body as something three-dimensional and having resistance, he sums up the reasoning with ‘Thus, as far as the concept of body in concerned, it is inapprehensible whether there is any body’ (PH3.46). Another example is in the section on place in Against the Physicists, where, having introduced an Aristotelian definition of place and raised difficulties about it,³⁰ he concludes ‘So the apprehension of place does not go well in terms of this kind of concept [kata tēn toiautēn noēsin]’ (M. 10.36).³¹

The second point is that extended discussion of dogmatic concepts seems to be much less common in Outlines of Pyrrhonism than in Sextus’ other works. It will perhaps have been noticed that I have cited few examples from Outlines, and this is not accidental; there are just not many to choose from, whereas in the other works they are plentiful. I think that this is easily accounted for precisely by the ‘outline’ character of this work, of which Sextus frequently reminds us. As this section has illustrated, it is to some extent an arbitrary matter, in addressing the views of the dogmatists, whether one focuses on their concepts or on the existence or knowability of the entities they postulate. And it is therefore something of a luxury to be able to do both, giving space first to conceptual matters and then to questions of existence or apprehensibility (often including a further dose of conceptual discussion). In the longer works, which are much more discursive than Outlines, it is not difficult for Sextus to do this. But in order to stick to his plan for Outlines, he needs to be much more restrictive about it.

4 Sextus’ Own Use of Concepts

We have seen Sextus talking about shared human concepts; we have also seen him talking about the concepts devised by the dogmatists. What about his own use of concepts? I have already noted two ways in which the holding of concepts might be thought to carry with it the holding of definite beliefs. First, with at least some concepts, to have them at all seems to bring a presumption that the types of things picked out by them do exist; for example, it is hard to see why a certain concept of the criterion of truth would have developed unless people thought there actually were criteria that fell under this concept. And second, many concepts seem to include beliefs internal to them; for example, the concept of nobility understood as including resistance to outrageous abuses of authority, which might be expressed as the belief that part of what it is to be noble is to resist authority when exercised in this way. How, then, can a sceptic, who purports to lack definite beliefs, employ concepts, if they come with such a baggage of belief? While scholarly opinion has differed over the extent of Sextus’ withdrawal from belief – especially on whether it applies only to theoretical beliefs or extends also to everyday beliefs³² – for the present purpose this issue will make little difference. For even if he claims to lack belief only about theoretical matters, the question remains as to how he can discuss the dogmatists’ theories in the great length that he does, using, needless to say, the same concepts as the dogmatists themselves.

And this is the context in which Sextus himself addresses this matter. Both in Outlines of Pyrrhonism and in Against the Logicians, he considers an objection brought against the sceptics on this very point. While the formulation of the objection is not identical in the two works, the basic idea in both is that if one understands the dogmatists’ concepts enough to engage in debate with them, one must already accept the reality of the things they are talking about – whereas if one does not, there is nothing to discuss. In Against the Logicians, the objection comes up in the specific case of demonstration; Sextus attributes it to ‘some people, and especially those of the Epicurean school’. It goes as follows: ‘Either you conceive what demonstration is or you do not conceive it. And if you conceive it and have a concept of it, there is demonstration; but if you do not conceive it, how can you investigate what you don’t even conceive to begin with?’ (M. 8.337). In Outlines, it has a much more prominent position, at the very start of the consideration of dogmatic theories in books 2 and 3. Here it is attributed not to anyone by name, but to ‘those who are always going on about [tous aei thrulountas] how the sceptic cannot either investigate or think about the things they hold doctrines about’ (PH2.1). The options, according to these people, are either that one apprehends (katalambanei) the things the dogmatists talk about or one does not. If one does, one clearly does not suspend judgement about those things; but if one does not, one cannot talk about them either (PH2.2).

Sextus’ replies in the two places differ significantly, but there is a point common to both that will be key. As others have stressed,³³ in Against the Logicians he offers two responses that are plainly inconsistent with one another. The first one concedes that having a concept is accompanied by a belief that things are as represented by that concept.³⁴ Hence, Sextus says, if he had just one concept of the object he is considering, he would indeed be vulnerable to the objection. But in fact, given the disagreements among the dogmatists, he finds himself faced with many different concepts of the same thing, and hence is forced to suspend judgement among them (M. 8.333a). Immediately afterwards, however, he gives a second answer that consists precisely in rejecting the idea that having a concept carries with it any beliefs about the object: ‘the preconception and concept of the object is not its reality’ (M. 8.334a), and hence there is no problem in a sceptic’s having the concepts of the things posited by the dogmatists. In fact, he adds, if the sceptic was vulnerable to this objection, so would be any dogmatist when it came to discussing things he does not believe in (such as an Epicurean discussing the idea of four basic physical elements) (M. 8.335a).

The reply to the objection in Outlines includes no trace of the first response from Against the Logicians, and indeed that response does not seem typical of Sextus’ approach. While he is not shy about indicating differences among dogmatic concepts in a certain area, he does not generally point to these differences as itself a route to suspension of judgement; rather, he will tend either to attack them separately one by one, or he will extract an element of agreement among them as the basis for his subsequent discussion – we have seen examples of both.³⁵ But the Outlines response does contain a version of the second response in the other work, including some helpful expansion on it, as we shall see. As others have noted, in Outlines Sextus makes things rather easy for himself in the way he sets up the objection.³⁶ If ‘apprehends’ means ‘knows the truth of’, it seems pretty obvious that one does not need to apprehend something in order to have a concept of it; and again, he has fun with the fact that this objection, if successful, would also bar the dogmatists from considering anything with which they disagree (PH2.4–6), or from investigating things they are not yet sure about (PH2.6–9). But the core of his response (like Against the Logicians’ second response) is that it is perfectly possible to have a concept of something without taking that thing to be real (PH2.10).

Let us return to the two ways in which, as I noted at the start of this section, beliefs seem to be implicated in concepts. The first of these was that it is hard to imagine why one would even have concepts (or some concepts, anyway) unless one believed the corresponding objects existed. Now that we have looked at Sextus’ defense of his own use of concepts, I think we can see that this is formulated too crudely. While it may indeed be hard to see how a certain concept could have developed in the absence of widespread belief in the existence of that kind of thing, it does not follow that everyone who now uses that concept must believe in the thing’s existence; examples to illustrate this are easy to find (ghosts, witches, etc., or for that matter, god or biological evolution). And once the point is stated in this way, it of course poses no difficulty to Sextus’ sceptical procedure or his defense of it here. However, the second point I mentioned, that concepts often seem to have beliefs internal to them, may look as if it poses more of a threat to him.

But here is where the details of Sextus’ response in Outlines become significant. Specifically what he says is ‘The sceptic is not, I think, prohibited from conceiving [noēseōs], which comes about by reason³⁷ from the things that strike passively [pathētikōs] and appear to him plainly, and do not at all bring in the reality of the things conceived’ (PH2.10). The crucial point here is that the sceptic’s acquisition of concepts happens ‘passively’. It does not come about through a process of seeking to pin down the necessary and sufficient conditions for something’s being an X (as in the dogmatic definitions that we talked about earlier), and certainly not through an act of assenting to the conceptual connections thus established. Rather, concepts simply occur to one. This could happen as one grows up; a concept will gradually form in one’s head and come to seem the obvious way to think of something, without any active endorsement on one’s part.³⁸ Or it could happen when one is mature and has become a sceptic, and is looking at the ideas of the dogmatists; one will see how a certain dogmatist thinks of some entity or process – demonstration, say, or time – and will allow this way of thinking to enter one’s own repertoire of concepts. This does not mean that one will take on board the dogmatist’s intellectual commitments. Rather than accepting the components of the definition as embodying a set of necessary and sufficient conditions for something to be, for example, a demonstration, one will either think of the definition as what the Stoics (or whoever) call demonstration; or, to the extent that one adopts the concept for one’s own use, one will think of it as encapsulating some convenient, but certainly revisable, connections between ideas, so that when one thinks of demonstration, the elements in the definition will be part of what comes to mind – much as fire comes to mind when one sees smoke, as we saw earlier in the case of the recollective sign. Equally, this last scenario may apply to new concepts that occur to the sceptic quite apart from any borrowing from the dogmatists.

And despite the passivity, there is nothing wrong with calling this an exercise of reason (logos), as he does in the passage quoted just now.³⁹ In the chapter early in the first book of Outlines of Pyrrhonism on how the sceptic can act (PH1.21–4), the general answer is ‘by following how things appear’. How things appear is, again, something passive; it is a matter of what happens to one (peisis, pathos) and is ‘not willed’ (aboulētos), and whether or not something appears to one a certain way (unlike whether or not it actually is that way) is ‘not up for investigation’ (azētētos) (PH1.22). Expanding on this picture, Sextus lists four major types of ways things appear; and the first of these is ‘by guidance of nature’ (huphēgēsei phuseōs, PH1.23), about which he simply says that in virtue of this, ‘we are naturally such as to perceive and to think’ (aisthētikoi kai noētikoi) (PH1.24). Our thinking capacity, then, like our perceiving capacity, is simply a matter of the way we are constructed, and it will work without our having to endorse or assent to anything. This may include our tendency to reason in certain ways – for example, to be unprepared to accept contradictory claims simultaneously. We need not try to give any justification for this; that we think like this is just part of how we are. And it surely also includes the fact that concepts form in our heads and are deployed in the ways touched on in the previous paragraph.⁴⁰

Take the example of Sextus’ concept of scepticism itself, as explained in the first book of Outlines (PH1.5, 8–10). As we saw in section II, this has the superficial appearance of a definition, but lacks the aspects of a definition that would be objectionable from a sceptical point of view. It lays down a number of related ideas, not as fixed truths about the nature of the matter, but as a report of his experience of living as a sceptic and reflecting upon his activity. It is thoughtful, but it does not include assertions that purport to have settled anything. It does not incorporate definite commitments about what scepticism is, as the dogmatists’ definitions incorporate commitments about how things are. Rather, it simply expresses the fact that, in considering scepticism itself, he regularly finds certain ideas occurring to him, in a certain order and with a certain structure (as smoke suggests fire, but with a little more complexity); and this order and structure is something that he is able to convey to others in writing. This is his concept of scepticism, and this is what the sceptic’s concepts are like in general.

Whether this account of how one can form and make use of concepts without holding definite beliefs is ultimately acceptable is open to further debate.⁴¹ But I think it is clear enough that this is the kind of account Sextus wishes to give on this subject. And so, while he acknowledges that some people think he faces a problem here, he is quite comfortable that they do not have a solid case. Having and using concepts, in the sceptic’s laid-back fashion, is one thing; having definite beliefs is another. And if he is right about this, then of course he is perfectly entitled to subject the dogmatists’ theories to scrutiny, using their concepts and, as I have tried to document in the previous sections, employing a variety of strategies that are precisely about concepts.