Plato's Theaetetus is an acknowledged masterpiece, and among the most influential texts in the history of epistemology. Since antiquity it has been debated whether this dialogue was written by Plato to support his familiar metaphysical doctrines, or represents a self-distancing from these. David Sedley's book offers a via media, founded on a radical separation of the author, Plato, from his main speaker, Socrates. The dialogue, it is argued, is addressed to readers familiar with Plato's mature doctrines, and sets out to (...) show how these doctrines, far from being an abandonment of his Socratic heritage, are its natural outcome. The Socrates portrayed here is the same Socrates as already portrayed in Plato's early dialogues. While not a Platonist, he is exhibited - to put it in terms of an image made famous by this dialogue - as having been Platonism's midwife. In a comprehensive rereading of the text, Sedley tracks the ways in which Socrates is shown unwittingly preparing the ground for Plato's mature doctrines, and reinterprets the dialogue's individual arguments from this perspective. The book is addressed to all readers interested in Plato, and does not require knowledge of Greek. (shrink)

In the whole Corpus Platonicum, we find in principle only one "direct argument" (Charles Kahn) for the existence of the ideas (Tim.51d3-51e6). The purpose of the article is to analyse this argument and to answer the question of why Plato in the Timaeus again defended the existence of the ideas despite the objections in the Parmenides. He defended it again because the latent presupposition of the apories in the Parmenides, the substantial view of sensibles, is removed through the introduction of (...) space as "substantialized extension". First (I) it is shown that Plato remained in dialogues, like the Sophist and Politicus, faithful to the "theory of ideas" despite his criticism in the Parmenides. The common theme in the trilogy of the Theaetetus, Sophist and Politicus is to refute relativism by showing that any relativism presupposes something absolute that is something like the "theory of ideas". The second part of the paper (II) examines closely the logical structure of the argument for the existence of ideas in the Timaeus (51d3-52a7). The third part (III) shows how this argument can avoid the criticism of ideas in the Parmenides. In the Parmenides, sensibles are treated as substantial entities. But, as the Timaeus shows, sensibles are not substantial entities but merely qualities, namely qualities of space, which is the only substance in the sensible world. A shortened English version of the paper appeared in Proceedings of the Fourth Symposium Platonicum, Granada, Selected papers, ed. by T. Calvo/L. Brisson, Academia Verlag, St. Augustin, 1997, 179-186. -/- But the only "direct argument" (Tim.51d3-51e6) seems to be interestingly flawed. Cf. Ferber, Rafael; Hiltbrunner, Thomas, (2005). (shrink)

In the first part of Plato's "Theaetetus" Socrates examines the definition "knowledge is perception". The long and arduous discussion begins with the assumption that knowing and perceiving are the same thing, and it ends with the conclusion that knowing is something completely different from perceiving. In making explicit the implications of Theaetetus' 'first child' Socrates first introduces an account of both perceiving and thinking that amounts to saying that whatever we perceive or think is true. This 'infallibilist' account is true (...) in a world in which everything changes in the way described by what I call the flux-ontology. However, if this account were correct, we would not be agents of our beliefs. Our beliefs would instead be things that happen to us. Without being rational, active agents of our process of forming beliefs, we would not be able to justify, to correct, and to discuss our beliefs. In his analysis of "perceiving" and "grasping being and truth", Socrates then puts things right by showing that our capacity of perceiving in the broader sense of the word is intrinsically judgmental. The upshot of the first main part of the "Theaetetus" can be understood as Plato's discovery of the propositional nature of perceiving. (shrink)

The "Theaetetus" and the "Sophist" both stand in the shadow of the "Parmenides," to which they refer. I propose to interpret these two dialogues as Plato's first move in the project of reshaping his metaphysics with the double aim of avoiding problems raised in the "Parmenides" and applying his general theory to the philosophy of nature. The classical doctrine of Forms is subject to revision, but Plato's fundamental metaphysics is preserved in the "Philebus" as well as in the "Timaeus." The (...) most important change is the explicit enlargement of the notion of Being to include the nature of things that change. This reshaping of the metaphysics is prepared in the "Theaetetus" and "Sophist" by an analysis of sensory phenomena in the former and, in the latter, a new account of Forms as a network of mutual connections and exclusions. The division of labor between the two dialogues is symbolized by the role of Heraclitus in the former and that of Parmenides in the latter. Theaetetus asks for a discussion of Parmenides as well, but Socrates will not undertake it. For that we need the visitor from Elea. Hence the "Theaetetus" deals with becoming and flux but not with being; that topic is reserved for Eleatic treatment in the "Sophist." But the problems of falsity and Not-Being, formulated in the first dialogue, cannot be resolved without the considerations of truth and Being, reserved for the later dialogue. That is why there must be a sequel to the "Theaetetus.". (shrink)