What is a concept? How are concepts formed? Are we born in possession of at least some concepts, or are all concepts acquired through experience? Is their content determined by the operations of the mind or the reality outside, or by an interaction between mind and world? How far do concepts reflect realities and, if so, what are these realities? How are concepts related to universals? How are they related to properties, species, and definitions? Moreover, how are concepts expressed in language and, in particular, how are they connected to general terms whose content, according to many theories, is just the corresponding concept? In the end, are concepts mental representations or abstract objects such as meanings or, perhaps, some combination of both? Furthermore, what might be the methodological, epistemological, or even ethical implications of different accounts of concepts? And very generally how, according to different theories, might concepts shape human experience? All these questions are very much alive in contemporary philosophy, but they also have a long history stretching back to the beginnings of Greek philosophy.
As far as the Greek philosophers are concerned, this history is not linear. Nor has there ever been a single concept of concept either in antiquity or in modern times. In fact, it is questionable whether the early Greek philosophers had any notion or notions corresponding to what we might call concept(s), and it can even be debated whether such items can be found in Plato or Aristotle. There are no prima facie grounds for assuming that Greek philosophical thinking about concepts can be explained along simple developmentalist lines. It seems that, like the moderns, the ancients were driven by different theoretical motivations and thought about concepts and related notions in a variety of ways.
The contributors of this volume avoid prejudging what the ancients take concepts to be, do not assume that concepts are involved in a theory unless this fact is made explicit by the ancient authors, and show themselves aware of the fact that, while some of the features that the ancients considered to be the marks of concepts do have contemporary equivalents, others do not. Generally, a main aim of this volume is to explore different ancient approaches to concepts and related notions, and to highlight elements that are distinctive to various Greek philosophers and schools. The chapters of this volume are arranged roughly and approximately in chronological sequence, not to convey the idea of a linear evolution of the subject, but mainly in order to display distinctive and original elements in ancient Greek thinking about concepts and show how, in many cases, later authors built on the intuitions and theories of earlier authors or/and shaped their views through dialectical interaction with their peers.
The present volume is intended to fill a major gap in the literature. Even though the very existence of concepts has occasionally been questioned, many philosophers of the past and many of our contemporaries would agree that concepts are basic features of rationality. However, virtually every pivotal issue concerning them has been controverted. There is extensive literature on these debates in medieval and modern philosophy and, of course, substantial philosophical contributions in both the analytic and the continental traditions. Surprisingly, however, this is not the case for Greek philosophy, the tradition of the commentators, and the Church Fathers. To our knowledge, there are no comprehensive studies addressing when or how notions akin to what we might call concept appear in the authors of the pre-classical, classical, and post-classical periods, nor which questions ancient philosophers in the Greco-Roman tradition asked and answered about concepts, let alone which theoretical presuppositions enabled the ancients to articulate different notions of concept to the extent that they did so. The present collection of studies aims to fill that lacuna by exploring significant moments in the early history of theorising about concepts and by tracing philosophical debates relevant to concepts from the end of the archaic age to the end of Greek antiquity and beyond.
The contributions in this volume serve philosophical purposes as well. In this respect the situation is fairly complex because, on the one hand, Greek philosophers often think about concepts in terms that are familiar to us, but on the other hand, they also attribute importance to aspects of concepts that modern and contemporary philosophers pay little or no attention to. The commonalities between ancients and moderns include, for instance, that the Greek philosophers appear to assume that at least some categories of concepts derive from perception. Also, ancient thinkers explore issues regarding a priori concepts, the intellectual processes assumed to involve such concepts, and the role of experience in that regard. Furthermore, Plato’s Socrates arguably operates with a distinction drawn by the moderns as well, between a conceptual investigation of the conditions of the proper use of a concept and a search for the essence of the thing that makes up the concept. Plato, Aristotle, and later thinkers raise and, in some cases, appear to work systematically on questions concerning the conditions of concept-acquisition, the structure of different sorts of concepts, the hierarchical relations that may obtain between these latter, and various ways of distinguishing acts of thinking and objects of thought.
Moreover, the ancient texts are relevant to ongoing debates concerning the vexed question of whether concepts are mental representations or some sort of abstract objects or both. While most ancient philosophers appear to favour the view that concepts are mental representations, Stoicism notoriously manifests a concern about the mind-independence and universality of ‘meanings’, and Stoic semantics has standardly been interpreted along Fregean lines. Besides, many ancient philosophers appear to maintain that concepts are involved in active thinking and self-reflectiveness, and they indicate that there is a tight connection between concepts and language. Also, with a few possible exceptions, such as ‘the secret theory’ developed in the first part of Plato’s Theaetetus, ancient philosophers arguably exhibit a strong externalism with regard to concepts: their content is determined by features of external reality rather than by the processes of our own minds.
However, it has also been deemed especially important to give voice to concerns that are distinctive of ancient approaches to concepts but are not prominent in contemporary debates, and to assess the concerns of the ancients on their own terms. The studies in this volume show that such distinctive features of ancient theories have considerable philosophical interest. For instance, ancient discussions about concepts have a characteristic, predominantly epistemological spin. Given the externalism of ancient theories, certain categories of concepts are claimed to give us an infallible grasp of reality and to function as criteria of truth. Other differences between the ancients and the moderns that deserve attention concern, for example, the idea that humans are paradigmatic concept-users and paradigmatic language-users. While several modern philosophers drive a sharp wedge between humans and animals in that regard and argue that language is necessary for the possession and use of concepts, ancient philosophers appear to take for granted that there is a connection between the application of a concept and the use of a corresponding word, but in many cases they do not determine the exact relation between concepts and language, nor do they explore the relation between humans and other animals in that regard. We hope that the targeted explorations conducted in this volume will open new perspectives and will inspire current-day philosophers as well as historians of ancient philosophy.
Part of the work conducted in these studies involves close attention to the technical or quasi-technical terminology used by the ancient authors to talk about concepts and related notions. This terminology is rich and varied and can often lead to significantly different interpretations of the texts. For instance, there is room for legitimate debate about Socrates’ meaning in Parmenides 132b, when he briefly flirts with the suggestion that Forms are noēmata. The term ‘noēma’ can mean ‘act or episode of thinking’ and, consequently, Socrates can be taken to entertain the suggestion that Forms are thinkings. Alternatively, ‘noēma’ can mean ‘product of thinking’ or ‘object of thought’. On the latter understanding of the term, the idea that Socrates is considering is quite different, namely that Forms are objects of thinking, and the relevant argument must be interpreted accordingly. Likewise, several items of Aristotle’s vocabulary related to concepts are under debate. One such case concerns the meaning of ‘ennoēma’ in a central passage of the Metaphysics (Metaph. A.1). Whether ennoēma in that context is the same as noēma in Posterior Analytics 2.19 has an important bearing on the issues of whether ennoēma is only of particulars or also of universals, whether ennoēmata have propositional content, whether the ennoēmata of experience are memories or thoughts, and in the end whether or not they are concepts.
Complications related to terminology are particularly acute in the Hellenistic period. The situation is especially complex regarding the Epicureans, partly because of the extensive and nuanced vocabulary that they use and partly because they are not consistent in their use of ‘ennoia’ and ‘ennoēma’. In their extant remains, ‘ennoia’ can mean either ‘conception’ or ‘concept’, and many other terms occur as well: ‘noēsis’ (sometimes rendered by ‘notion’), and also its cognates ‘nooumenon’ and ‘epinooumenon’; ‘epinoia’ (usually translated as ‘thought’ or ‘conception’); ‘huponoia’, ‘dianoia’, ‘perilēpsis’, ‘hupolēpsis’, and of course ‘prolēpsis’ (‘preconception’) – a term that also occurs in Stoicism and refers to a special category of concepts naturally formed in the mind and epistemically infallible (in Latin ‘praenotiones’, ‘anticipationes’, and frequently ‘notitiae’ or ‘notities’).
Interpretative assessments of the Stoic theory crucially depend on how one interprets the occurrences of ‘prolēpsis’ in Stoic texts as well as other key expressions that the Stoics use to denote concepts or different kinds of concepts, notably ‘phusikai ennoiai’ (‘natural conceptions’), ‘koinai ennoiai’ (‘common conceptions’), and ‘ennoiai’ simpliciter. Especially important for terminological and interpretative purposes is the Stoic distinction between ‘ennoia’ and ‘ennoēma’ (‘conception’ or ‘act of thinking’ and ‘concept’ or ‘object of thinking’), for, arguably, the Stoics apply this distinction consistently across the board.
The terms ‘ennoia’ and ‘ennoēma’, as well as prolēpsis and other related words, are also part of the terminology of Pyrhonnian Scepticism as reported by Sextus Empiricus. Sextus, however, exhibits what seems to be deliberate indifference to the systematic distinction observed by the Stoics between ‘ennoia’ and ‘ennoēma’, and the same holds for the technical use of ‘prolēpsis’ to refer to preconceptions. He employs ‘ennoēma’ rarely and interchangeably with ‘ennoia’, and uses ‘ennoia’, and ‘prolēpsis’ indiscriminately. For instance, he talks about people having conflicting ‘prolēpseis’, whereas, technically speaking, this would be an impossibility, and he refers to the ennoia or koinē ennoia or prolēpsis of the divine. He also treats ‘epinoia’ as a near synonym of ‘ennoia’ , and he employs ‘noēsis’ to refer sometimes to an act of thinking and other times to the thing thought.
Turning to later authors, the Platonists appear to disregard the Stoic distinction between ‘ennoia’ and ‘ennoēma’, although they occasionally mobilise that distinction for polemical purposes. In the writings of Alexander of Aphrodisias, ennoēma occurs only once (Top. 359.13–16), and noēma is used rarely, mostly in the sense of the object of thinking or the object of knowledge present in the soul. As for ‘ennoia’, Alexander uses it in contexts highlighting its connection to sense perception and the capacity to acquire knowledge. Stoic expressions such as koinai ennoiai, common conceptions, acquire new connotations and are used in new contexts, including Alexander’s polemics against the Stoic school.
Plotinus too uses ‘ennoēma’ in the sense of ‘concept’ only sparingly and for polemical purposes. However, he makes regular use of ‘ennoia’ in the sense of ‘conception’ to refer to our grasp of abstractions such as number – a use markedly different from the standard Stoic use of that term. When it comes to concepts in the soul, Plotinus employs a variety of terms whose correct interpretation requires close examination and analysis: logos, eidos (in the soul or the intellect), ennoia, epinoia, noēma, dianoēma, ennoēma, and to katholou (the universal). These may or may not indicate distinct kinds of concepts, may be generic or more specific, and may refer to concepts, thoughts, or propositions.
A different set of terms and, correspondingly, a different host of problems is raised by the texts of the Church Fathers: for example, whether ‘dianoia’ can mean only ‘concept’ or also ‘conception’ or ‘thought’; what are the respective uses of ‘ennoia’ and ‘epinoia’; whether different Church Fathers view concepts as mental items or linguistic items or both; how the many human epinoiai (concepts) of God can square with the unicity and simplicity of the divine; and so on.
The studies in this volume pay systematic attention to issues like the ones indicated above. A methodological assumption shared by the authors is that sorting the terminology of concepts and related notions is not merely a lexical matter, but also an inextricable part of the analysis of substantive philosophical questions. In this respect too, the contributions in this collection represent, we believe, pioneering work, and advance considerably both relevant scholarship and philosophical reflection.
As indicated, the studies of this collection are arranged in approximate chronological order mainly for systematic and exegetic purposes; they cover a period of roughly a millennium.
The volume begins with ‘The Emergence of the Concept in Early Greek Philosophy’ by André Laks. The chapter argues that we can trace the first inklings of thinking about concepts by paying close attention to early Greek answers to the following three questions: how perceptual information reaches and is processed by the mind, the nature of the relationship between perception and thinking, and how the early Greek philosophers account for name-giving. First, André Laks discusses whether the explanations of sensory mechanisms (and, in particular, the way in which ‘images’ coming from the outside create ‘imprints’ (tupoi) in the mind) offered by the early Greek philosophers as well as by the medical authors might have prepared the ground for later theories of concept formation. Second, he argues that we should resist the Aristotelian report according to which the early Greek philosophers identified thinking with perceiving. In fact, we have good reasons to assume that early Greek philosophers attempted to offer an account of the process of thinking. The final section of the chapter turns to the question of the relationship between giving names to things and forming and grasping the corresponding concept. In this respect, Parmenides’ theory of naming is of particular interest: it is by establishing names for multifarious things, and first for the two antithetical principles, created and characterised in their thoughts, that mortals populate the world by giving it a derivate stability that preserves something of the characteristics of being.
In ‘The Place of Concepts in Socratic Inquiry’, Terence Irwin examines Socrates’ question ‘What is F?’, which is often taken to be a request for some sort of definition or account of F. When Socrates asks, ‘What is courage?’, ‘What is piety?’, ‘What is temperance?’, does his discovery that everyone he has met, including himself, cannot answer such questions in a satisfactory manner imply that these answerers do not know what the words mean? If one cannot answer the ‘What is F?’ question, does it follow that one lacks the concept of F? Irwin argues that conceptual argument has an indispensable role in the arguments that lead to Socratic definitions, but it will not take us all the way to them. To understand Socratic definitions, Irwin compares them with Aristotelian real definitions, and with Epictetus’ views on the articulation of preconceptions. These issues also underlie and occasionally surface in the three subsequent chapters on Plato.
In ‘Early Learning in Plato, Republic 7’, James Warren provides an analysis of Socrates’ account of the sort of early learning needed in order to produce philosopher-rulers in Republic 7 (521c–525a), namely a passage describing a very early encounter with questions that provoke thoughts about intelligible objects and stir up concepts in the soul. James Warren explains how concepts of number, more specifically the concepts ‘one’, ‘two’, ‘a pair’, and so on, play an essential role in these very early stages of the ascent towards knowledge, and he stresses the continuity between the initial and very basic arithmetical concepts and the concepts involved in more demanding subjects taught in later stages of the educational curriculum. On this account, Socrates is prepared to ascribe to more or less everyone, an acquaintance with some, albeit elementary, intelligible objects. This in turn can shed some light on broader debates in Platonic epistemology about the extent to which all people – not just those whom Socrates calls philosophers – have some conceptual grasp of intelligibles.
Engaging directly with the question of whether Platonic Forms are concepts, David Sedley’s chapter ‘Are Platonic Forms Concepts?’ takes its start from the Parmenides 132b–c, where Socrates and Parmenides briefly examine the hypothesis that Forms are ‘thoughts’ (noēmata). Sedley asks what ‘thoughts’ are in that context, and argues that they are not thought contents, but acts of thinking. The chapter offers an ambitious and comprehensive analysis of the classical theory of Forms as showcased in the Phaedo, Republic, Parmenides, and Timaeus, in terms that clarify why Plato was bound to reject the hypothesis considered in the Parmenides (132b–c), namely that Forms are thoughts.
Lesley Brown’s paper ‘Do Forms Play the Role of Concepts in Plato?’ begins by noting a major issue of controversy concerning the Forms in the middle dialogues, namely whether Forms are explanatory properties whose role is to account for why things are the way they are, and are therefore the objects of philosophical inquiry and knowledge, or whether Forms are concepts whose role is to explain everyday thinking and discourse. On the assumption that the former option best captures the role of Forms in Plato’s so-called Middle Dialogues, Lesley Brown addresses the question of whether Plato’s later dialogues manifest a shift in emphasis such that the latter interpretation (of the Forms as concepts intended to explain everyday thinking) gains greater prominence. She revisits the question in the Sophist, but also considers other important and relevant texts from the Theaetetus, the Phaedrus, and the Statesman. In her view, even though Plato’s later dialogues show increasing interest in matters of language and meaning, and hence may perhaps be taken to show a somewhat greater interest in the role Forms or Kinds play in our everyday thinking and discourse, the prominence of the method of division in these works nonetheless underscores that the Forms are primarily properties discoverable by philosophical inquiry, not everyday concepts or meanings.
Problematisation about concepts and related notions in Aristotle takes different guises that greatly depend on the particular work or works of Aristotle under consideration.
Richard McKirahan’s contribution ‘Concepts and Concept Formation in Aristotle’s Logical Works’ argues that an account of how concepts are formed may be extracted with due caution from passages of the Organon, on topics relating to the problem of how we gain knowledge of scientific principles, in combination with Aristotle’s statements on the relations among objects in the world, affections in the soul, and language. Aristotle’s view is pieced together on the basis of the account in Posterior Analytics 2.19, supplemented by the parallel account in Metaph. A.1, as well as Aristotle’s remarks on the utility of dialectic for the sciences in Top. 1.2 and the brief discussions of epagōgē (frequently and controversially rendered by ‘induction’: An. post. 1.18 and 1.31). Over the course of the argument, the chapter also addresses questions about the nature of perception as conceived in the Organon, the epistemic status of experience, the nature of the transition from the awareness of individuals to the grasp of universals, the status of nous both as an epistemic state and as a mode of grasping certain facts and universals, and the relation between universals and concepts.
Even more complex than in the Organon is the examination of concept in the context of Aristotle’s metaphysics. The chapter ‘Concepts and Universals in Aristotle’s Metaphysical Thought’ by Christof Rapp starts out by acknowledging that Aristotle does not have a general term for concept, and then examines which entities in Aristotle’s metaphysical theory might play the role of concepts. In outline, Christof Rapp argues that many of Aristotle’s discussions focus on the meaning of general terms and the question of whether or not they signify something real and existing independently and in its own right. In Christof Rapp’s approach, Aristotle remains committed throughout to the view that universals as captured by genuine definitions are crucial for human knowledge and understanding. Insofar as Aristotle resists a conception of universals as existing in the way that particular substances do, however, he can be taken to intimate that universals are ‘merely conceptual’. In the Metaphysics, he distances himself from the view that universals such as genera and species qualify as substances. His main contribution to our thinking about concepts principally consists in the view that both universals and embodied substantial forms have mental counterparts, by which we grasp and understand the things falling under the conceived form or essential definition. On a plausible interpretation of that claim, we thus get to grasp and understand the things falling under a given concept.
In ‘Aristotle on the Stages of Cognitive Development’, Thomas Kjeller Johansen undertakes to examine Aristotle’s contributions to our thinking about concepts from a different perspective, namely in connection to Aristotle’s psychology. He revisits Aristotle’s account of how we acquire universal concepts mainly on the basis of Metaphysics A.1, Posterior Analytics 1.31 and 2.19, and the De Anima. The starting point of the chapter is a puzzle. On the one hand, Aristotle points out (An. post. 1.31, 2.19) that we perceive the universal in the particular. On the other, he suggests (Metaph. A.1) that it is only when we have craft and science that we grasp the universal, while perception, memory and experience all are concerned with the particular. Building on the widespread view that, according to Aristotle, the universal grasped in craft and science is a certain kind of universal – namely, the universal cause – Johansen argues that we should understand perception, memory, and experience teleologically, as stages in the ordering of perceptual information that allows this causal concept to emerge.
Moving on to the Hellenistic period, we find that new aspects of the notion of concept are highlighted or emerge. Experience is the cornerstone of Epicurean philosophy and nowhere is this more apparent than in the Epicurean views about the nature, formation, and application of concepts. So far as we can tell, our own chapter ‘Epicureans on Preconceptions and Other Concepts’ constitutes the first attempt to date which offers a general account of Epicurean theorising about concepts and conceptions. Our aim is to piece together the approach to concepts suggested by Epicurus and his early associates, trace its historical development over a period of approximately five centuries, compare it with competing views, and highlight the philosophical value of the Epicurean account on that subject. It is not clear whether, properly speaking, the Epicureans can be claimed to have a theory about concepts. However, an in-depth discussion of these questions will show that the Epicureans advance a coherent if elliptical explanation of the nature and formation of concepts and of their epistemological and ethical role. Also, we hope to show that although the core of the Epicurean account remains fundamentally unaffected, there are shifts of emphasis and new developments marking the passage from one generation of Epicureans to another and from one era to the next.
Comparable and parallel developments occur in Stoicism as well. Indeed, the Stoic philosophers of all periods show a keen interest in concepts in the context of their logic, semantics, and philosophy of language. In ‘The Stoics on Conceptions and Concepts’, Katerina Ierodiakonou offers an account of the Stoics’ distinction between ennoiai and ennoēmata (‘conceptions’ and ‘concepts’), and also of the distinctions suggested by the standard Stoic terminology of concepts also mentioned above: notably, prolēpseis (‘preconceptions’), phusikai ennoiai (‘natural conceptions’), and koinai ennoiai (‘common conceptions’). All these terms appear intended to point to general notions that play a central role in the acquisition of human knowledge, but it remains puzzling how exactly the Stoics understood them or why they introduced them into their doctrine in the first place. Katerina Ierodiakonou addresses these issues, as well as further questions debated in the secondary literature. These include: whether all human beings necessarily possess concepts or are simply able to possess them? What is the content of conceptions and how it is determined? What is the ontological status of conceptions and concepts, and what are their epistemological functions?
The views about concepts advanced and debated by the dominant philosophical schools did not go unchallenged. The works of Sextus Empiricus deploy a variety of sceptical strategies against them. In his chapter ‘Doing Things with Concepts in Sextus Empiricus’, Richard Bett examines in detail Sextus’ terminology in connection to his use of such strategies and highlights the inventiveness and sophistication of the latter. On the one hand, Sextus appears to be in agreement with his dogmatic opponents in so far as he too says that we need to get our concepts clear before proceeding to investigate any topic. On the other hand, he often raises objections against dogmatic concepts, arguing, for example, that they are inherently inconsistent and therefore there are no objects corresponding to such concepts or, alternatively, that even if we accept these concepts, nothing real exists which corresponds to them. It is not clear whether or how these two lines of approach can be coherently combined. The former seems to be a neutral exercise in clarification that serves as a prelude to counter-argument, while the latter is itself a source of counter-arguments. Nonetheless, Sextus frequently runs the two together, and Richard 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.
The next two contributions do not study specifically one author or school.
Matthew Duncombe’s chapter ‘Relative Concepts’ addresses this question: what are relative concepts according to ancient philosophers? Scholars have typically held that either ancient thinkers had no clear concept of relatives; or they conceived of relatives in a way that is a trivial variation on Frege’s treatment of relative concepts as doubly incomplete. Duncombe argues that, in fact, Plato, Aristotle, and the Stoics have a clear concept of relatives, distinct from incompleteness approaches, which he calls ‘constitutive relativity’. The core idea of constitutive relativity is that the relation it bears to an exclusive correlative constitutes a relative. Duncombe goes on to discuss particular philosophers and schools in detail. In the examination of Agathon in Plato’s Symposium, Socrates understands relative concepts in general, and love in particular, on the constitutive model. Aristotle’s concept of relatives in Categories 7 draws on Plato, but Aristotle addresses a worry that Plato did not: relative concepts might be vacuous. The Stoics focused on concepts as mental items and Duncombe shows what Stoic relative concepts may have been. As with Plato and Aristotle, exclusivity plays a key role in Stoic relativity, and so a Stoic relative concept is the concept of a relative that relates exclusively to a correlative. Finally, Duncombe examines a sceptical argument put forward by Sextus which raises a worry about any conception of relativity where relatives relate exclusively to their correlatives.
The chapter ‘Concepts in Greek Mathematics’ by Reviel Netz problematises a set of assumptions commonly encountered in the literature on Greek mathematics. These assumptions have to do with both the object and the purpose of mathematics in Greek Antiquity, and they typically derive from a supposedly objective, a-historical conception of mathematical theory and practice. In sharp opposition to that tradition, Reviel Netz raises the possibility that the purpose of engaging with mathematical concepts may have been different in antiquity than what it has standardly been taken to be. He asks central questions afresh, for instance why do mathematical texts begin with definitions, or what is the purpose of mathematical definitions and of axioms. In connection to these issues, he highlights new aspects of the relationship between Greek mathematics and Greek philosophy, between engaging with mathematical concepts and philosophical thinking. And he advances the thesis that the relations between mathematics and philosophy changed through the various eras of antiquity, and so did mathematical concepts and the role of mathematical definitions. We should seriously entertain the idea that even mathematical concepts need to be viewed within a given historical and cultural context.
Both the Platonists and the Peripatics put pressure in different ways on the Stoic views on concepts, and the three subsequent contributions examine facets of these debates.
In ‘Platonist Notions and Forms’, Mauro Bonazzi explores an aspect of the Platonists’ engagement with Stoic epistemology, namely the Platonists’ appropriation of the Stoic ennoiai, conceptions or notions, to show that Plato’s doctrine can provide a satisfactory answer to the problem of the foundation of knowledge, which Stoicism has proved unable to solve. As mentioned, the Stoic ennoiai, (conceptions) or phusikai ennoiai (natural conceptions) are notions naturally arising in the human mind and constituting the basic elements of human reason. They are ‘natural’ in the sense that humans are naturally disposed to acquire them, and they are koinai (common) in the sense that all humans have them or are disposed to have them. They are also invariably true and therefore can serve as criteria to increase knowledge, promote scientific understanding and contribute to the good life. It is these ennoiai that the Platonists integrate in their own reinvention of Plato’s epistemology and employ in their polemics against their principal rivals.
The chapter ‘Contested Concepts: Plutarch’s On Common Conceptions’ by Thomas Bénatouïl addresses the question of how ordinary concepts, for instance, a layman’s concept of a spider, intersect with a zoologist’s concept of that insect. While from the epistemological point of view the latter’s concept should be allowed to prevail, from the point of view of semantics and the philosophy of mind it is not at all obvious that the scientific concept of spider should be allowed to rule over the corresponding lay concept, nor is it obvious that there is only one concept of spider whose content can be fixed for every context. Clearly, the Academics and the Stoics were aware of the importance of this and related problems. Plutarch’s dialogue On Common Conceptions, subtitled Against the Stoics, is a representative text of these schools’ respective stances, and its study by Thomas Bénatouïl aims to bring out both its historical significance and systematic interest.
The chapter ‘Alexander of Aphrodisias on Concepts’ by Frans A. J. de Haas takes up another aspect of concept theory, that is, the endeavour to define what a concept is. Furthermore, he explores the interactions between the Peripatetics and the Stoics, as they are evidenced by Alexander, on ontological as well as psychological and epistemological issues. De Haas also offers a systematic study of part of Alexander’s rich vocabulary denoting concepts, thoughts, and universals, and of a correspondingly rich collection of verbs referring to the human activities of abstracting or constructing concepts. Importantly, this analysis throws light on Alexander’s understanding of ennoia and noêma, and on Alexander’s views concerning the epistemic reliability of concepts and the unity of concepts in the human soul.
As Sara Magrin points out in ‘Plotinus on Concepts’, Plotinus’ views on concepts have so far received little attention, whereas his views on ennoiai, conceptions, have been more widely discussed. This is partly due to the varied vocabulary that Plotinus uses to refer to what we might call concepts, assuming that the latter are understood as mental items distinct from thoughts. Sara Magrin’s chapter focuses on one important passage of the Enneads (Ennead 6.6.12–14) which offers a critical discussion of an account of the concepts (ennoēmata) of one and numbers commonly attributed to the Stoics. The chapter pursues the twofold aim of reconstructing the account in question and of interpreting and assessing Plotinus’ criticism of it. This has scarcely if ever been attempted in the scholarship, both because the evidential value of that passage in respect of the Stoics has been deemed questionable and because Plotinus’ criticism of the Stoic concept of number is extremely compact and difficult to articulate. The main contribution of Sara Magrin’s analysis consists in her use of Plotinus’ criticism of the Stoics as evidence, on the basis of which she pieces together Plotinus’ views on concepts.
Péter Lautner’s chapter ‘Concepts in the Neoplatonist Tradition’ expands the scope of the enquiry by discussing Platonist theories of concept formation in Late Antiquity. Generally speaking, the philosophers belonging to the so-called schools of Athens and Alexandria believed that the articulation of our rational capacity and the acquisition of knowledge somehow derives from the senses as well as the intellect, and they mostly agreed that some elements of concept formation, notably generalisation, occur on the basis of sense-perception. They disagreed, however, as to whether or not such generalisations are full-blown concepts. While all the philosophers under consideration endorse some version of the view that the main source of concepts is our intellect, which essentially contains fully fledged concepts, their accounts vary in respect of the intellect’s ability to project concepts onto the lower cognitive faculties. The problem of how the two kinds of concepts mentioned above are related to each other occupies the Platonists through the entire period under examination and constitutes the focus of Péter Lautner’s analysis.
The last chapter of the volume ‘Early Christian Philosophers on Concepts’ by George Karamanolis integrates some of the themes encountered in previous chapters in the broad theological perspective of the early Christian thinkers, according to which explorations in every area of philosophy are ultimately intended to reveal aspects of God’s relation to His creation. It is argued that, on the whole, the position of the early Christian philosophers on concepts is part of their perceptual realism and their stance against scepticism. George Karamanolis examines three case studies: the theories of Clement of Alexandria, Origen, and Gregory of Nyssa. In all three cases, he maintains, concepts are treated both as mental representations and semantic/linguistic items through which we grasp reality. Clement develops his view on concepts in the context of an anti-sceptical elaboration of his thesis that knowledge of the world is propositional and attainable by humans, while Origen and Gregory of Nyssa defend more sophisticated theories of concepts in connection with their respective epistemologies. In every case a theological question motivates the Christian author’s stance regarding the nature and formation of concepts.
To our knowledge, there is no volume that is closely similar to the present one either in English or in any other European language. There are, however, two other books that reflect on particular aspects of the notion of concept or on particular phases of its development. Although the study of definitions does not exhaust the topic of concepts, the collection of essays edited by David Charles, Definition in Greek Philosophy (Oxford 2010) should be of interest to many readers of this volume. The same holds for the monograph of Christoph Helmig, Forms and Concepts: Concept Formation in the Platonic Tradition (Commentaria in Aristotelem Graeca et Byzantina, Bd 5, Berlin/Boston Reference Helmig2012), which addresses broader issues regarding the formulation of a theory of concepts and concept formation, concentrating exclusively on the Platonic and Aristotelian tradition. So far as our own editorial aims are concerned, it has been our wish to publish original and informative studies rather than survey-like articles. The contributors develop and defend their respective positions on the basis of different methodological and philosophical approaches, trying to avoid overlap to the extent that this was possible. The main text is accessible to those who cannot read the classical languages, since all Greek and Latin terms are transliterated and are translated into English on their first occurrence and on most subsequent occurrences. Phrases and passages cited in the original languages are confined to the footnotes. Our intended audience comprises philosophers as much as specialists in Ancient Philosophy and other fields of the Classics. We hope that our readers will find the studies published in this volume as stimulating and pleasurable as we believe them to be.
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