Lee Klein

This chapter examines Plato’s Theaetetus, the dialogue most explicitly devoted to the question “What is knowledge?” Despite this central focus, the dialogue ends aporetically without a definitive answer. The analysis centers on key arguments that shape the role of δόξα in it: The Contradiction Argument (161d–162a, 168c–171c) and The Reasoning Argument (184d–187a), both targeting Theaetetus’ first definition of knowledge as perception; The Puzzles of False Belief (188a–200a), which reveal how differing premises affect outcomes; The Judges Example (200a–201c), refuting the second definition of knowledge as true belief; and The Dream Theory (201e–202c), testing but ultimately rejecting the third definition of knowledge as true belief with λόγος. The discussion highlights how these refutations shape the distinction between belief and knowledge and concludes by assessing the philosophical value of belief within the dialogue.

In this chapter, I draw together the results of the study by characterizing the epistemic value of belief in Plato’s philosophy. The analysis has shown that belief is a versatile concept, capable of being true or false. Its value lies in enabling correct judgments about the sensible world, in providing an indispensable basis for inquiry into the intelligible, and in its potential to develop into knowledge. However, it likewise remains precarious, given belief’s vulnerability to lapse into ignorance. The study has established truth as the essential criterion of any valuable belief: only true beliefs can be evaluated in terms of their accuracy, clarity, usefulness, and stability, each of which admits of degrees. On this basis, epistemic progress can be understood as a movement from unstable and unclear true beliefs toward more accurate, clarified, and stabilized ones through investigation into their causes. In light of this account, the guiding questions of the study are here answered by drawing on the results of the entire investigation.

This chapter offers a close analysis of five arguments from Plato’s Republic that are central to the dialogue’s treatment of δόξα and its relation to knowledge. The first, The Departure Argument (Book III, 412e–413c), though often overlooked in research, provides a valuable link to the Meno by addressing the (in)stability of belief and showing the continued significance of the notion of δόξα as presented in the earlier dialogue in the Republic. The Dreaming Argument (Book V, 475e–476d) and The Objects Argument (Book V, 476e–479d), embedded within the rich passage 474b–480a, are then examined. While the former presupposes acceptance of the theory of Forms, the latter proceeds from more widely accepted premises. The fourth and fifth arguments, The Divided Line (Book VI, 509d–511e) and The Allegory of the Cave (Book VI, 514a–521b), further develop the epistemological framework by illustrating the correlation between the ontological and epistemic realms and by metaphorically describing the ascent to knowledge.

This chapter examines Plato’s Philebus as a valuable, though often overlooked, source for understanding the relation between knowledge and belief. Focusing on Socrates’ evaluation of different forms of knowledge, it reconstructs four central arguments concerning the status of belief in the dialogue. The Kinship Premise (11b–c) establishes the epistemic relevance of belief; The Double Ignorance Premise (48c–49a) highlights the danger of false knowledge claims; The τέχναι Argument (55c–59c) explores the variety of knowledge, including practical expertise; and The Price-Giving Argument (59e–66c) demonstrates the breadth of the concept of knowledge, extending even to certain forms of belief. The analysis concludes by addressing the four guiding questions of this study by drawing on the epistemological significance of δόξα in the Philebus.

In this chapter, three passages from the Meno that contain especially rich arguments about the nature of belief and its relation to knowledge are examined: The Slave Boy Argument (85b–86b), The Road to Larissa Argument (96e–97d), and The Tethering Argument (97e–98a). Each argument is discussed in its own subsection, following a brief introduction situating it within the dialogue. The chapter concludes by synthesizing these analyses and addressing the four guiding questions of this study in light of the findings from the Meno.

This chapter investigates the status of δόξα in Plato’s Timaeus, where the interplay between myth and philosophy complicates epistemological analysis. Four arguments are examined: The Ontological Premise (27e–28a), which grounds the cosmological account in distinctions necessary for later inquiry; The World Soul Argument (36e–37c), which expands the epistemological framework; The Human Soul Argument (44b–47b; 86b–87b), combining two complementary accounts of human genesis; and The Receptacle Argument (49d–51e), which further refines the distinction between νοῦς and δόξα through an ontological partition. The chapter concludes by addressing the guiding questions of the study in light of these analyses, highlighting the hybrid nature of knowledge and belief in the Timaeus.

Although the topic of this study is ancient, the question of the value of belief and its distinction from knowledge remains both relevant and difficult to answer. Plato’s notion of δόξα cannot be straightforwardly equated with a modern understanding of belief, nor can the distinction between belief and knowledge be resolved through a single framework applicable to both ancient and modern theories. Nevertheless, engaging with Plato’s epistemological reflections not only contributes to scholarship but also fosters critical thinking about the validity of belief and the processes by which belief and knowledge are formed. The Introduction to this study outlines its four guiding questions and explains the selection of dialogues to be examined, together with an overview of prior research on δόξα in Plato. It also sets out the methodological approach and structure of the study. By means of a comparative, systematic, and exegetical analysis of key arguments, this work aims to offer a fresh appraisal of δόξα in Plato, with particular attention to the positive role that belief plays in his epistemological conceptions.

As the first monograph to specifically focus on the positive evaluation of belief (doxa) as a crucial concept in Plato’s epistemology, this work contributes significantly to scholarly research by offering a fresh perspective that deepens our understanding of Plato’s theory of knowledge. It shows that doxa is indispensable to the acquisition of knowledge in the human life, thus disproving the long-held notion that Plato was a mere idealist in this respect. The author examines the nuanced, multifaceted role of belief in a well-chosen selection of Platonic dialogues (Meno, Republic, Theaetetus, Philebus, and Timaeus), challenging traditional as well as modern interpretations by letting belief step out of the shadow of knowledge. By offering detailed analyses of relevant arguments, engaging with previous research and providing an innovative interpretation, it is shown that doxa is not only a central but a highly versatile concept in Plato. This study appeals especially to scholars of ancient philosophy and epistemology as well as to all students of philosophy interested in Plato and epistemology.

Scholarship on the Republic has tended to stress the centrality of the tripartite soul to the Republic’s conception of justice. Yet since Socrates’s task in the dialogue is to show the desirability of justice in the ordinary Athenian sense, any emphasis on idiosyncratic psychology would render his account of justice fundamentally beside the point. This paper suggests a way out of this dilemma. It argues that Platonic justice in the Republic represents a shrewd twist on the entirely conventional, distributive Athenian notion of justice as refraining from seizing for oneself what belongs to another. Plato’s twist is to substitute the performance of one’s own activity (πρᾶξις τα ἑαυτοῦ) for the possession of one’s household goods (ἕξις τα ἑαυτοῦ) as the proper object of justice. The paper then shows how this account of Platonic justice makes sense both textually and contextually, before concluding.