Marcelo D. Boeri Empiricist Platonic epistemology and the internalist-externalist debate in the Theaetetus Introduction: The Theaetetus as an “epistemological” dialogue It is tempting to suggest that Plato’s Theaetetus is the founding text for epistemol- ogy as an autonomous domain of philosophical inquiry.1 Indeed, it provides sev- eral remarkable discussions about issues that have become classical themes in the epistemological explorations (within and beyond Greek philosophy). If the Theaetetus is to be claimed as the work to take epistemology as an autonomous domain of philosophical investigation, this assertion should be nuanced. In fact, it is arguable that Plato’s epistemology cannot be understood independently of other disciplines (such as metaphysics and philosophy of language, for example) to which we also tend to give certain autonomy. Even accepting that the The- aetetus deals with issues that go beyond epistemology, there has been a patent tendency in the literature to consider this dialogue as a work fundamentally epis- temological;2 to be sure, the Theaetetus explores the necessary and sufficient con- ditions of knowledge, tries to determine what knowledge is and (probably follow- ing and developing the project of the Meno)3 how it differs from, and is more valuable than, true opinion (thus significantly advancing the problem of the value of knowledge, an issue that has recently moved to center stage in contem- porary epistemological investigations).4 Now if epistemology can be characterized as the theory of knowledge and its justification, and if it is certain that (as I intend to argue) the Platonic remarks against the perceptual definition of knowledge go beyond what usually is taken to be epistemology in the sense of the discipline that is concerned with the sources of knowledge, its necessary and sufficient conditions, when one is justi- fied in claiming to know something, etc., Plato’s epistemology in Theaetetus does 1 This chapter is a partial result of the Fondecyt Project 1150067 (Chile). 2 Polansky 1992, 11–15. Sedley 2004, 18. Ferrari 2011, 10–11. 3 On this see Kahn 2013, 48. 4 Haddock, Millar, Pritchard 2009, 1–2; 14–15; Goldman and Olsson 2009, esp. 21–23. Weiner 2009. https://doi.org/10.1515/[eISBN_pdf] Marcelo D. Boeri not look very epistemological from a contemporary perspective.5 However several arguments provided by the character Socrates in the Theaetetus are aimed at showing that knowledge cannot be perception (αἴσθησις) and at highlighting the necessity proceeding to the level of (true) belief/opinion (δόξα), and even to true belief/opinion plus a logos. Although all these definitions of ἐπιστήμη are sys- tematically demolished, Plato (through his spokesman Socrates) continues to think that, even in the rejected definitions, there are some ingredients that are significant in the pursuit for knowledge. For instance, knowledge is not percep- tion, but perception, Plato appears to contend, is a necessary condition for opin- ion (see Tht. 161d3–4). Thus, given that opinion seems to be a decisive ingredient 5 Even though Plato is taken to be a forerunner for the view that knowledge is a justified true belief (Tht. 201c8–d1); this definition of knowledge is widely accepted in contemporary episte- mology (i.e. if one has a true belief, and such belief is justified, then that belief counts as knowledge; otherwise, it does not). See Davidson 1986, 308, and 2004, 4. Cf. also Fumerton 2002, 206–207, who notes that one should distinguish beliefs about experience (that are justified by the very experience, like in the belief that I am in pain, which is justified by the pain itself) from beliefs of facts, which cannot be justified by perceptual experience. Plato apparently does not make explicitly this distinction, but he arguably should have presupposed it. On this issue see Reeve 1989, 43; Benson 2000, 15. Plato (sadly for many people) also demolishes the definition of knowledge as true belief plus logos; a Platonic scholar might argue that it is always hard to know if by logos Plato is saying exactly the same thing as ‘justification’, such as this word is used in contemporary epistemology. However, in so far as in contemporary philosophy it is assumed that an epistemic justification is the reason (or line of reasoning) which warrants the veracity of one’s belief or assertion, it seems that Plato is not too far from what contemporary philosophers suppose about this matter. Plato defines knowledge as ‘true doxa plus a logos’ in other dialogues, too (Men. 98a2; Prt. 336b9–c1-2; Phd. 76b5–6; 97d–99d2; Smp. 202a5–9; Resp. 534b3–7). In the Ti. 51e5, a dialogue that is supposed to be later than Theaetetus, that characterization of ἐπι- στήμη reappears. Empiricist Platonic epistemology and the internalist-externalist debate in the Theaetetus of knowledge (otherwise it would not be possible to think of knowledge in prop- ositional terms)6 and that opinion somehow stems from perception,7 there is a way in which one should assume that perception is involved in knowledge. In the Phaedo this is quite clear: we do not get the knowledge of the Equal Itself from seeing sticks or stones that are equal, and despite the Equal Itself and perceptible things that are equal are different, it is from the equal things that one has con- ceived of and grasped the knowledge of the Equal Itself (Phd. 74c7–9). This being so, perceptual items seem to ‘trigger’, as it were, our recollection of Forms. But the relevance of perception is not less important in the Theaetetus,8 where it is 6 Against the possibility that Plato is willing to endorse the view that there is propositional knowledge, see Gerson 2003, 37. Gerson’s argument (as far as I understand it) depends on the contrast between knowledge and belief (as argued by Plato in Resp. 5); such contrast, he claims, suggests that knowledge is non-representational, but belief (δόξα) involves some kind of repre- sentation. As long as propositions represent facts or states of affairs and knowledge is non-rep- resentational, then knowledge is non-propositional (Gerson, 2003, 160-161). Now the thesis that ἐπιστήμη and δόξα are mutually exclusive does not appear manifestly in the Tht. where, on the contrary, Plato regards true δόξα and true δόξα plus a λόγος as two plausible definitions of ἐπιστήμη (202c7–8). It is true that these definitions are turned down, but it is arguable that they contain some valuable ingredients that, within the dialogue, are sound in the continuous pursuit of knowledge. In fact, it seems reasonable that, whatever knowledge may finally be, it must be true and since for Plato the primary locus of the truth (propositionally, not ontologically under- stood) is λόγος (Sph. 263a–d), and λόγος is tantamount to δόξα, it does follow that knowledge somehow should be related to δόξα. 7 This is almost explicitly said in the text (Tht. 179c2–4). 8 Where the presence of Forms is at least debatable; for a defense of the view that regards ‘the commons’ not to be Forms, see the balanced discussion by Ferrari 2002, 160–164. At Tht. 185a– e it is clear that the common features oppose to the proper or specific ones, that is, the percepti- ble contents which are specific to a sense organ (see Tht. 185d9–e2: ὄργανον ἴδιον … αὐτὴ δι᾽ αὑτῆς ἡ ψυχὴ τὰ κοινά … ἐπισκοπεῖν). Thus what Plato must be pointing out is simply that there is a set of predicates (being, same, other, like, unlike, honorable, dishonorable, good, bad) to which we have access independently of our sense organs, i.e. properties that are not accessible through the body (see Sedley 2004, 106–107; Ferrari 2011, 82–84; Kahn 2013, 63–64). There are several passages in the Theaetetus where Plato appears to refer to the transcendent Forms (alt- hough those passages do not refer to the ‘commons’); the allusion to ‘paradigms’ (παραδείγματα) in 176e3 has been seen by some scholars as an unequivocal reference to the Forms (McDowell 1996, 176). As is well known, ‘paradigm’ is a term frequently employed by Plato to refer to the transcendent Forms in the middle and later dialogues (Resp. 472c–e; 484c; 500e; Ti. 27d5–29d3). However, as suggested by Sedley, in the context of the Tht. it is quite clear that Plato is not inter- ested in introducing the doctrine of Forms, but in emphasizing his faith in the absolute goodness of god (Sedley 2004, 79). At any rate, that Plato is not alluding to the Forms throughout the The- aetetus is inconclusive; there are some passages where Forms appear to be in the background (‘encapsulated’, as it were); see, for example, 176a8–b1, where the ‘two world metaphysics’ is implicitly suggested. The wording ‘from here to there’ also evokes the famous allegory of the Marcelo D. Boeri particularly emphasized that sense perception is the way through which human beings come into contact with the external world from the very moment they are born, thus suggesting that αἴσθησις is the first source of knowledge (sensible knowledge) and that human beings perceive all those affective states that, through the body, reach the soul (Tht. 186b11–c2). If this is so, sense perception should play a relevant role in knowledge; besides, the epistemological arguments supplied in the Tht. when exploring what knowledge is (and when focusing on the three main definitions of knowledge that, at any rate, are turned down) show that Plato was certainly interested in debating the matter of knowledge (which in a sense is a truism) and thereby good reasons exist for stating that the core of the dialogue is epistemological in character. But it is Plato himself who extends this “theoretical” discussion to the relevance that it has at the practical domain.