In a recent and inspiring article titled “Ancient Philosophy for the Twenty-First century”Footnote 1 Julia Annas remarks that one of the most important changes undergone by the discipline of ancient philosophy in the twentieth century was “to join the mainstream of analytical philosophy”. She writes:

Taking ancient philosophy up into the mainstream of analytical philosophy was a tremendous catalyst … It also made philosophers who had assumed that history of philosophy was just history of ideas realize that, to take one example, Aristotle’s subtle and difficult account of the soul could provide real philosophical illumination in the context of modern philosophy of mind, and was worth serious, uncondescending discussion. (2004: 28)

The present volume contributes to the study of ancient theories of perception and cognition along the direction Annas describes.

In thinking about how we grasp cognitively the external world, contemporary epistemologists concentrate on questions of this sort: Is knowledge justified true belief? How is knowledge different from true belief? More generally, what is knowledge? How many varieties of knowledge are there? What are the sources of knowledge? What is its structure, and what are its limits? Why is knowledge more valuable than true belief?

This volume looks at how ancient thinkers answered some of these questions, spanning the most influential positions held in antiquity, by Plato, Aristotle and Plotinus.

In his contribution to this volume, “Knowledge as True Belief plus Individuation in Plato”, Theodore Scaltsas examines afresh Plato’s account of knowledge and belief in Republic V, where Plato explores the idea that they are two different cognitive powers, as different between them as e.g. sight and hearing; their operation is different and their objects are different. Plato claims that knowledge, which the philosophers possess, attends to Forms, while belief, which the lovers of sights possess, attends to the many objects of our experience. But already in Republic V Plato realises that in order to understand the difference between the Forms and their participants, the philosophers must be able to discern the Forms from the many objects of experience—which is a distinction that the lovers of sights fail to make. In virtue of the fact that s/he can discern this distinction, the knower has a partial cognitive contact with the many. Scaltsas argues that Plato develops this into an account of a single cognitive power which underpins both knowledge and opinion; this cognitive power functions as knowledge or opinion under different external conditions, attending to different types of object for each of them. When operating infallibly on the Forms, the power operates as knowledge, while when operating fallibly on the sensible objects it operates as opinion. What is needed to enable this power to operate as knowledge, rather than as opinion, is the provision of the right enabling conditions. Such conditions consist in having an individuation account for the object of the cognitive power. One merit of this interpretation, Scaltsas concludes, is that the Republic V account of knowledge as a different power from belief is shown to be compatible with and develop into Plato’s account of knowledge as a type of belief in other parts of his work.

The investigation into Plato’s views on knowledge and belief continues with the papers of Deborah Modrack and Catherine Rowett, both of whom focus on the Theaetetus.

In her “On making mistakes in Plato: Theaetetus 187c–200d”, Rowett investigates anew a famous part of Plato’s Theaetetus where Socrates develops various models of the mind (picturing it first as a wax tablet and then as an aviary full of specimen birds). These models aim to solve some puzzles about how it is possible to make a mistake. Rowett offers a novel interpretation of the texts in question, arguing that the discussion of mistakes is an essential part of Plato’s refutation of Theaetetus’s thesis that knowledge is true belief. Knowledge cannot be reduced to the application of descriptions to particulars, but is to be found in the prior possession of abstract descriptions that can be deployed in identifying particular individuals. Mistakes are the proof of this. To be mistaken about p is to mis-describe p. But in order to apply falsely a description, one must first have known it from somewhere else.

In her “Meaning and Cognition in Plato’s Cratylus and Theaetetus Modrack interprets the two dialogues in question as Plato’s attempts to identify the elemental cognitions that are the foundation of language and knowledge. Modrack argues that in the Theaetetus Plato aims at an analysis of cognition such that it identifies the elemental cognitions, and accounts for knowledge in a way that does justice both to its distinctive character and to its components and mode of composition.

In the Cratylus, Modrack argues, Plato’s goal is to achieve refinement of linguistic concepts so that they truly capture what is real. But accounting for this process in a way that provides justification for claims to knowledge is not easy, since language seems to limit what can be known. Plato’s examination of these issues is thorough and brings to light the difficulty of explaining how the mind grasps what is real. She concludes that modern proponents of coherence theories of truth and relativism about meaning and truth might feel reassured in holding conclusions about the nature of knowledge and reality that Plato drew only to reject. Even so, these theorists might find Plato’s reasons for stopping short of embracing these positions instructive.

Timothy Chappell, in his “Varieties of knowledge in Plato and Aristotle”, develops the proposal that it might be fruitful for philosophers in general, and epistemologists in particular, to give attention to the existing varieties of knowledge: in addition to propositional knowledge, knowledge-how and experiential knowledge matter too. Underpinning all of them, Chappell argues, there is a fourth kind of knowledge which was actually focal for both Plato and Aristotle but has been neglected in contemporary epistemology: objectual or substantial knowledge, that is knowledge of things rather than propositions.

Understanding the primacy of objectual knowledge for the ancients will help us to grasp better a variety of positions held in antiquity and possibly puzzling us nowadays; for example, why Socrates in the Meno thinks that if we can first get a clear knowledge of virtue itself, then everything else about it, e.g. whether it can be taught, will become clear too. It is only once we have that objectual knowledge that we can expect to be able to spell out its consequences at the levels of propositional knowledge (first the definition of virtue, and then other truths about virtue), of experiential knowledge (what virtue “looks like”, how it strikes us in practice), or of knowledge-how (what kinds of pattern of action virtue leads to).

Chappell remarks on the exploratory nature of objectual knowledge. One either knows a proposition, or fails to know it. It is much more natural to speak of intellectually exploring an object of knowledge than a known proposition. In this way objectual knowledge is always and intrinsically more like understanding than propositional knowledge is.

Riccardo Chiaradonna’s contribution, “Plotinus’ account of the cognitive powers of the soul: Sense perception and discursive thought”, turns to a different set of questions and a later thinker within the Platonic tradition.

Chiaradonna focuses on perceptual experiences the justification for our epistemic states. According to direct realism, we can acquire knowledge because we can directly perceive such objects. This is Plotinus’ position, argues Chiaradonna, defending Plotinus from the charge of a seeming contradiction. The contradiction seems to stem from the fact that Plotinus holds that we make judgments regarding how the external world is by means of discursive reasoning, and what he argues elsewhere regarding our perceptual apprehension of the external world. Chiaradonna throws light on this puzzle by leaning on additional textual evidence, from which we learn that for Plotinus there exist some sense perceptions of which we are unaware.

The final contribution to this volume, by Thomas Johansen, looks at the relation between body and soul in Aristotle. In his “Capacity and Potentiality: Aristotle’s Metaphysics Θ.6–7 from the perspective of the De Anima”. Johansen argues that Aristotle’s account of the soul as the fulfillment of a body having life potentially seems a perspicacious illustration of the way in which we can think of concurrent matter as being the substance in capacity, that is, of being determinable by the substance’s form as an end.