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Title: Not bringing things to a standstill : Plato's Theaetetus on how (not) to speak about a world in which knowledge is perception
Author: Eelink, Guus Willem
ISNI:       0000 0004 5428 2111
Awarding Body: University of Oxford
Current Institution: University of Oxford
Date of Award: 2020
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This thesis is concerned with Theaetetus' definition of knowledge ('Knowledge is perception') and Protagoras' Measure Doctrine ('Man is the measure of all things') as discussed in Plato's Theaetetus (151e-187a). I shall argue that Protagoras' Measure Doctrine is best understood as a doctrine of infallibilism: all beliefs are true. I shall argue that Theaetetus' definition commits Theaetetus to perceptual infallibilism: all perceptual beliefs are true. Further, I shall argue that Protagoras' Secret Doctrine (152d-160c) underpins perceptual infallibilism by means of a process ontology: perceptual properties are processes involving objects and perceivers. I shall argue that this process ontology explains three key components of the Secret Doctrine: the Relationalist Thesis ('Nothing is one thing just by itself'), the Flux Thesis ('Nothing ever is, but things are always becoming') and the linguistic reforms (the rejection of 'to be' in favour of 'to become'). I shall provide a detailed analysis and criticism of the relativist interpretation, according to which the Measure Doctrine amounts to relativism about truth: each belief is true (not simpliciter, but) in relation to the believer. In particular, I shall argue that the refutation of the Measure Doctrine (170c-171c) targets infallibilism rather than relativism about truth. I shall argue that the refutation of the Radical Flux doctrine ('Everything is always changing with every kind of change in every respect'; 179d-183c) hinges on the view that Radical Flux precludes universals from being instantiated. This view explains both the incompatibility between Radical Flux and Theaetetus' definition and the incoherence of Radical Flux. Further, I shall argue that neither Theaetetus nor Protagoras is committed to Radical Flux: the refutation targets proponents of Theaetetus' definition and of the Secret Doctrine who also endorse Radical Flux. Finally, I shall argue that the refutation of Theaetetus' definition (at 184b-187a) hinges on the view that perceiving does not-and knowing does-involve making true judgements.
Supervisor: Peramatzis, Michail ; Castagnoli, Luca Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Theaetetus ; epistemology ; ancient philosophy ; relativism