In the treatise devoted to eternity and time (III.7) Plotinus begins by reflecting on his own style of philosophizing. These reflections are one of the most important sources for understanding Plotinus's method in general, but it is worth considering them closely in the context of this particular treatise and its topic, for an understanding of Plotinus's approach will help us to follow and better evaluate the general direction of his argument. Plotinus presents us with six aspects. We begin our enquiry (1) with the general notions and presuppositions which will have formed in us a concept of time and of eternity. For Plotinus himself one important and central element of this is the linking of eternity with the unchanging and transcendent intelligible world and time with the physical world of becoming. Clearly Plato lies partly behind this. But what influences may have been at work in the formation of this preliminary concept are of no significance at this stage. Now (2) when we look at our ideas more closely we become more and more puzzled as objections and difficulties arise.

In this essay I shall address some philosophical issues that have to do with the relationship between cognition and its objects in Plotinus. This involves inquiring into the connection between Plotinus's epistemology and psychology, on the one hand, and his ontology, on the other. Interesting questions arise with respect to Plotinus's views both as regards the relation between sense perception and the sensible object and that of thinking and the intelligible object. One set of questions concerns realism versus idealism and subjectivism: Is there in general an essential connection between cognition and object in Plotinus such that the mode of cognition in some sense determines the object? This would imply idealism of some sort. One may also ask whether the immediate object of cognition is always something belonging to the subject of cognition as opposed to something extra-mental. Such a subjectivist position would place the extra-mental beyond the direct reach of cognition and might involve radical skepticism about it. Or is Plotinus neither an idealist nor a subjectivist and objects appear to be such and such because they are such as they appear independently of the mode of apprehension? Different stories may of course have to be told about intelligibles and sensibles with respect to these questions. So I shall in fact argue. Still it is interesting to inquire whether there are any common principles underlying Plotinus's views on both sensibles and intelligibles in this regard. This too I shall take up here.

Of the three first principles (archai) or hypostases, One, Intellect, and Soul, the One or Good is the most difficult to conceive and the most central to understanding Plotinian philosophy. It is everything and nothing, everywhere and nowhere. The One is the source (archê) of all beings and, as the Good, the goal (telos) of all aspirations, human and non-human. As the indemonstrable first principle of everything, as transcendent infinite being, and as the supreme object of love, the One is the center of a vibrant conception of reality many of whose facets resist philosophical analysis. Efforts to understand or to define the nature of the One, Plotinus believes, are doomed to be inadequate. We speak about it, but in reality these efforts only amount to “making signs to ourselves about it”; it is not possible for anyone to say what it is (V.3.13.7, 14.1-7). Despite this insistence on the ineffability of the first principle Plotinus talks about it constantly, making radical claims about its universal role in the structure of reality. Only by reflecting on the internal logic of his metaphysics can we recognize the multi-faceted nature of this unitary principle.

TALKING ABOUT THE ONE

Three interrelated factors motivate Plotinus's philosophy of the One: tradition, reason, and experience. Since the influence of his predecessors, especially Plato and Aristotle, on Plotinus is discussed in Chapter 1, here we will examine the contributions made by rational argument and personal experience toward articulating the metaphysics of the One.

An explicit distinction between essence and existence is first attributed to the Arabic philosophers Al Farabi (c. 870-950) and Avicenna (c. 980-1037). The nature or essence of any finite being can be conceived separately from its existence that appears to be a perfection “superadded” or accidental to its nature. Pierre Hadot has traced the roots of this distinction even further back to Boethius, and later Neoplatonism, and in the latter case to two principal sources: (1) the distinction between absolute being and determinate being (respectively being-infinitive, to einai, and being-participle, to on) found in the anonymous Commentary on the Parmenides (ascribed to Porphyry) and in Marius Victorinus. And (2) the late Neoplatonic distinction (of Proclus, Damascius and Victorinus) between pre-existence (huparxis) and substance (ousia), that is, between pure being in its simplicity prior to all things and substance as the determinate subject taken together with all its accidents. I shall argue here that the roots of this distinction are also to be found in Plotinus.

Readers of the Companion who have arrived at this chapter should be well aware of the fact that Plotinus was a Platonist. One might add that in spite of the fact that he has always been regarded as the founder of Neoplatonism, he himself would not have known what the Greek equivalent of that word might have meant, since all the Platonists of late antiquity regarded themselves as Platonists tout simple, and their philosophy as the exposition of the underlying truths of Plato's philosophy which Plato himself sometimes omitted to make explicit. The degree of self-deception involved in this selfconcept is perhaps nowhere clearer than in their discussions of soul and intellect. That is so because, while their conception of soul (psuchê) was fundamentally Platonic and dualist, their explanation of its operations owed much more to Aristotle and other post-Platonic philosophers than it did to Plato himself.

For Plotinus the dualism was as clear, if not as clear-cut. Though he was aware of materialistic theories of the nature of the soul, such as those of the Stoics, he was hostile to them and would have had little time for the great volume of modern discussion which goes under labels like materialism, physicalism, or functionalism. That is equally true for those theories which, under headings like epiphenomenalism and supervenience, allow for other than fully materialist explanations of what Plotinus would have seen as the most important functions of the soul and intellect - the thinking functions of mind.

Plotinus's highest metaphysical principle, the One or Good, is ineffable (V.3.13.1; cf. V.3.14.1-8; V.5.6.11-13; VI.9.5.31-2). Indeed, Plotinus is hesitant to attribute “good,” “is” (VI7.38.1-2), or even “one” (VI.9.5.30-3) to it. If the heart of his philosophical enterprise is to make meaningful statements about this principle, and furthermore our understanding of all else is informed by it, we may well ask why, in the light of this apparent despair of language, he would continue in his quest (his work extends to nine hundred and seventy-four pages of Oxford text).

Of course, in saying that the One is ineffable, Plotinus has already made a statement, albeit negative, about the One. So at least this negative statement is permissible. Further examination of the possibilities of negative language offers more fruitful ways out of the closure apparently imposed by the stricture of ineffability. Before we consider further the question of the One's ineffability, it will be useful to examine the uses that Plotinus makes of negation. Plotinus uses negation to avoid confusion of an incorporeal reality accessible only to the mind or spirit with a corporeal reality perceived by our senses.

INTRODUCTION

The epistemological debate between the Greek philosophical schools of the third and second centuries B.C. – the Skeptics on the one hand and the Stoics and Epicureans on the other – can be described without undue simplification as a dispute over the question of the criterion of truth. Strictly speaking, there were two questions: first, whether a criterion of truth exists, and second, what it might be. These questions can also be formulated without the expression “criterion of truth”: the debate centered on the question of whether it is possible to distinguish with certainty between true and false opinions or assertions, and if so, by what means. The Stoics and Epicureans defended the view that it is possible to make such a distinction, but differed over how it might be made. The Skeptics, on the other hand – Academics as well as “Pyrrhonists” – claimed that there is no criterion of truth, and that it is therefore impossible to distinguish between true and false opinions. From this they drew the well-known conclusion that it is impossible to know anything with certainty and hence it is necessary to refrain from any definite assertions.

Even though the problems which were at issue can be formulated in different ways, it seems obvious that we cannot properly understand or evaluate the way in which the Hellenistic philosophers put the question and attempted to answer it without first clarifying the sense of the question of the criterion.

In reading the doxographical reports on Stoic philosophy, one gets the impression that the Stoics had a singular, and often irritating, predilection for identity-statements. The best known case is undoubtedly that of nature, which is at the same time reason, fatum, providence and Zeus himself (Plut Stoic, rep. 1050b). But in ethics, too, one finds such series of identifications, which do not always make understanding the texts any easier. The goal of life, for example, eudaimonia, is supposed to consist in a life in agreement with nature, which is ostensibly the same as a life in accordance with virtue. And this in turn seems to be a life which is determined by the rational selection of that which accords with nature. Virtue, for its part, is designated as a ‘consistent attitude’ (diathesis homologoumenē, D.L. VII 89), as ‘knowledge of what is good, bad and neither of these’ (S.E. M XI 170, 184), and finally as ‘the art of living’ (technē peri ton bion, ibid., 170, 181, 184). These claims are not at all self-evident, and hence obviously require justification. But the explanations are mosdy omitted, or merely hinted at by the doxographers, so that part of the task of interpretation, a part unfortunately sometimes neglected, consists in finding the justifications.

As long as one does not know how an identity-statement is justified, one can hardly judge arguments in which it appears.

In this paper I would like to examine a conception of happiness that seems to have become popular after the time of Plato and Aristotle: tranquillity or, as one might also say, peace of mind. This conception is interesting for two reasons: first, because it seems to come from outside the tradition that began with Plato or Socrates, second, because it is the only conception of eudaimonia in Greek ethics that identifies happiness with a state of mind and makes it depend entirely on a person's attitude or beliefs. In this way it may be closer to more recent ideas about happiness, notably those of utilitarians who treat “happiness” as a synonym of “pleasure,” than to the classical Greek conceptions of the good life. For Plato and Aristode (and in fact for the Hellenistic philosophers too, including the hedonist Epicurus) the happy life certainly had to be pleasant or enjoyable, but they did not think that happiness itself consisted in being pleased with one's life. As the (somewhat unorthodox) Stoic Seneca puts it, “it is not that virtue is chosen because it pleases, but that, if chosen, it also pleases.” I will argue that tranquillity was in fact not a serious contender for the position of ultimate good in ancient times. Greek theories of happiness from Plato to Epicurus were attempts to spell out what sort of a life one would have to lead in order to have good reasons for feeling tranquil or contented; they were not recipes for reaching a certain state of mind.

Of the three statements that often serve to epitomize Epicurean philosophy – at least for polemical purposes – two seem to be reasonably easy to understand: “The universe consists of bodies and void,” for physics; and “Pleasure is the highest good,” for ethics. The third, epistemological one, however, which is usually quoted in English as “All sensations are true,” has been the subject of some controversy and various interpretations by recent commentators.

In this paper I will try to do three things. First, I will try to make a suggestion as to what might have been Epicurus' own wording of his thesis.

Second, I will examine what seems to be becoming a standard interpretation in recent literature, namely the view that the word ἀληθἑς in this context must be taken to mean “real” rather than “true.” I shall try to show that this interpretation is not as firmly based as it might seem to be.

Third, I will propose a fresh interpretation, taking ἀληθές in the traditional sense of “true,” which places Epicurus' thesis in the epistemological debate of his day, but which avoids some objections raised against earlier versions of the traditional view.

Difficulties begin with the words themselves. We do not have Epicurus' own version of his famous dictum, but it is fairly obvious from the consensus of our sources that he must have said something to the effect either that αἰσθήσεις or that all ϕαντασίαι are true.

It is no novelty to say that the Stoics saw themselves as followers of Socrates. According to Diogenes Laertius (7.2), Zeno turned to philosophy after reading the second book of Xenophon's Memorabilia. The Socratic descent of the Stoics was canonized into a school genealogy by the Hellenistic historians, who constructed the “succession” Socrates – Antisthenes – Diogenes – Crates – Zeno. As far as this suggests that each of the older philosophers was in some formal sense a teacher of the next, this is probably an exaggeration. However, it is easy to find typically “Socratic” doctrines in Stoic ethics – such as, for example, the conception of virtue as a kind of knowledge with its corollary, the denial of akrasia; the thesis of the unity of the virtues, and also, at least on one common ancient interpretation of Socrates, the notorious thesis that virtue is identical with happiness. But the genealogy also seems to indicate that the Stoics' Socrates was not, or not primarily, Plato's Socrates, but rather the Socrates of Antisthenes and the Cynics, or possibly Xenophon's. And indeed the Stoic system looks at first sight so different from what we seem to find in Plato's early dialogues that one might be inclined to think that the Stoic version of Socratic doctrine had very little to do with the Socrates of those dialogues. This may be the reason why recent studies of Stoic philosophy have tended, in the absence of extant texts by the major Cynics, to concentrate on the influence of Aristotle rather than Plato as a philosophical predecessor of Stoicism.

Hedonism, like pleasure, can take many forms, and its fundamental tenet, ‘pleasure is the good,’ is notoriously open to different interpretations. Also, the advice, moral and otherwise, given to people who try to pursue this good may vary a great deal, depending on one's view of what pleasure is. To say that a certain philosopher is a hedonist, therefore, is not yet to say much about the content of his doctrine. Still, one would at least expect a hedonist's conception of happiness to be that of a recognizably pleasant life. Epicurus' form of hedonism has seemed paradoxical from the beginning because it does not seem to meet even this modest expectation. In his own time, the Cyrenaics maintained that what he held to be the greatest pleasure was in fact more like the state of someone asleep (Diogenes Laertius II.89) or even dead (Clemens Alexandrinus, Stromateis II.21; Us. fr. 451). Cicero was certainly not the first to argue that Epicurus' doctrine was incoherent and his prescriptions for a pleasant life inconsistent with his principles. Plutarch devoted an entire treatise to showing that one cannot even lead a pleasant life following Epicurus' doctrine.

The difficulty both ancient and modern critics have felt lies in seeing how Epicurus could present his claim that the highest good was a state of absence of pain and trouble from body and soul, as a version of hedonism.

Towards the end of the fourth century B.C., Greek epistemology appears to undergo some dramatic changes. New technical terms are introduced by Epicurus and the Stoic Zeno, indicating a shift of interest from the question ‘What is knowledge?’ – given that there is such a thing – to ‘Is there any knowledge?’. The appearance of novelty may be due to the fact that so much of the philosophical literature of the fourth century is lost. There must have been a sceptical undercurrent from the time of the sophists on, most notably perhaps in the Democritean school. But we have to turn mainly to Plato and Aristotle to recover some of the evidence, and it seems that they had little patience with doubts about the possibility of knowledge. Seeing impressive disciplines like mathematics, astronomy, medicine and other natural sciences develop, they may have found it unnecessary to worry about their very possibility, and more important to investigate the structure of scientific theories and the characteristics of scientific understanding. They may also have thought that their doctrines, which tied knowledge to the universal, were not liable to the difficulties arising from conflicting appearances.

But the fourth century also produced Pyrrho, later seen as the founder of scepticism, by whom Epicurus, who belonged to the Democritean tradition anyway, is said to have been much impressed (Diogenes Laertius (D.L.) IX. 64).

Before I begin an examination of sceptical arguments, I should perhaps say a few words about the term ‘scepticism’ itself. ‘Scepticism’, as I propose to use the word, may be characterized by two features: a thesis, viz. that nothing can be known, and a recommendation, viz. that one should suspend judgement on all matters. These two are logically independent of each other, since the thesis is not sufficient to justify the recommendation. Both are susceptible of different interpretations, so that they do not determine the details of a sceptical philosophy. I think it would be fair to say that in modern times the thesis has been the more prominent feature, while the ancients seem to have considered the recommendation as equally important. In this paper I will be mainly concerned with the recommendation, i.e. with epochē, though the thesis will also come up in the discussion of the sceptics' defence of their position. However, its credentials will not concern us here. I shall start with a problem of interpretation that arises out of the tradition about Carneades. Next, I will discuss the respective replies of Arcesilaus and Carneades to two (Stoic) arguments against scepticism, as examples of two different ways of defending the sceptic position. Finally, I will return to the first problem to see whether the investigation of Carneades' way of arguing can shed some light on it.