In Metaphysics Γ 4-6 Aristotle argues that Protagoras is committed not just to denying the PNC, but also to asserting its contrary. In this paper, I offer an analysis of this commitment. I try to show that Aristotle is working with a specific idea in mind: a Protagoreanism ontologically linked to the flux doctrine, as Plato suggested in Theaetetus 152-160.

We examine the discussion about the definition of knowledge as true judgment accompanied by logos in Theaetetus 201c-210c, in order to ascertain which of the recent alternative interpretations is more consistent with the text. To accomplish this, we intend to analyze the text and explore in detail the secondary literature about it.

Há muita discussão sobre como interpretar o papel do argumento ‘Saber ou não Saber’ em Teeteto 188a-c. Alguns intérpretes supõem que esse papel é dialético e Platão não está comprometido com sua verdade. Outros pensam que o argumento revela a confusão de Platão sobre o tema da opinião falsa à época do Teeteto. Em minha análise, há uma terceira via que faz mais justiça ao que Platão está desenvolvendo em 188a-c. Penso que em 188a-c temos uma versão do princípio platônico (...) da infalibilidade. (shrink)

The paper offers an interpretation of a disputed portion of Plato’s Theaetetus that is often called the Secret Doctrine. It is presented as a process ontology that takes two types of processes, swift and slow motions, as fundamental building blocks for ordinary material objects. Slow motions are powers which, when realized, generate swift motions, which, in turn, are subjectively bundled to compose sensible objects and perceivers. Although the reading of the Secret Doctrine offered here—a new version of the “Causal Theory (...) interpretation”—is not without problems, these problems are acknowledged in Plato’s text, confirming that this interpretation is correct. (shrink)

This paper examines a passage in the Theaetetus where Plato distinguishes knowledge from true belief by appealing to the example of a jury hearing a case. While the jurors may have true belief, Socrates puts forward two reasons why they cannot achieve knowledge. The reasons for this nescience have typically been taken to be in tension with each other . This paper proposes a solution to the putative difficulty by arguing that what links the two cases of nescience is that (...) in neither case do the jurors act from an epistemic virtue and that doing so is a necessary condition of knowledge. Appreciating that it is a necessary condition of knowledge that it be the result of an epistemic agent's agency in a distinctive way provides a satisfying solution to the difficulty Burnyeat detected and also does justice to an otherwise neglected aspect of Plato's epistemology: his talk of cognitive capacities and virtues and his focus on what it is that is active and passive in epistemic processes. (shrink)

Any comprehensive interpretation of the "Theaetetus" has to provide answers to, among others, two very general questions concerning that dialogue: "What is Plato's relation to the problems faced in the "Theaetetus"?" and "What is the significance of the absence of the Forms from the discussion of the "Theaetetus", given their undoubted relevance to the topic of the dialogue, i.e. knowledge?" Predominantly, the answer given to the first question in the literature has been that the problems are those that Plato is (...) trying to tackle and the one to the second question, when it has been addressed at all, that the Forms are left out of the discussion because Plato no longer thought them relevant, either for having abandoned or seriously revised them, by the time of writing the "Theaetetus". In this study of the Wax Block and the Aviary models of judgment that occur in the second part of the "Theaetetus" as part of its discussion of the problem of false judgment, I argue that the problems faced there actually arise because of the neglect of Forms. The discussion of the second part is, I contend, carried out on a materialist ontology, an ontology assumed because it suits the definition of knowledge as true judgment which inaugurates that part of the dialogue, an ontology in no way subscribed to by Plato. The Wax Block is, I explain, a materialist model and fails in the case of judgments about numbers for treating them on a par with material subjects, ignoring their intelligible status. In particular, it fails to distinguish judging 5 and 7 to be 11 from judging 12 to be 11 because of its neglect of Forms; Plato would distinguish those judgments by distinguishing 5 and 7 from 12 with help from his part-whole analysis, to which the Forms are essential. (shrink)

This article aims at reconstructing the logic and assessing the force of Socrates' argument against Protagoras' 'Measure Doctrine' at Theaetetus 171a–c. I examine and criticise some influential interpretations of the passage, according to which, e.g., Socrates is guilty of ignoratio elenchi by dropping the essential Protagorean qualifiers or successfully proves that md is self-refuting provided the missing qualifiers are restored by the attentive reader. Having clarified the meaning of MD, I analyse in detail the broader section 170a–171d and argue, against (...) an extensive scholarly consensus, that it contains two slightly different formulations of the same argument, and not two distinct arguments, that Socrates does not highlight his own strategy at 171a–c as especially clever, and that his argument successfully shows that md turns out to be untenable for Protagoras himself when submitted to scrutiny in dialectical contexts, without aiming at proving its absolute falsehood. Finally, I clarify the philosophical import of the final image of Protagoras' momentary return from the underworld. (shrink)

The thesis of this paper is that the capacity to think of one’s perceptions as cross-modally integrated is incompatible with a reductionist account of the self. In §2 I distinguish three versions of the argument from cross-modality. According to the ‘unification’ version of the argument, what needs to be explained is one’s capacity to identify an object touched as the same as an object simultaneously seen. According to the ‘recognition’ version, what needs to be explained is one’s capacity, having once (...) seen an object, to reidentify that same object by touch alone. According to the ‘objectivity’ version, what needs to be explained is one’s capacity to think of one’s perceptions in different modalities as perceptions of one and the same object. The third version seems to establish that one must conceive of oneself substantially, as the numerically identical owner of one’s experiences, a conclusion in agreement with recent work in developmental psychology claiming to show that an infant’s cross-modal capacities are essentially implicated in their development of a sense of self. There is further work to be done if this is to be tumed into an argument against reductionism: there is no swift route from the epistemology of self-consciousness to the metaphysics of the self. In the §3, I will claim that there is, nevertheless, an argument linking the two. What I propose is an argument derived, not from the token-reflexive rule for the first-person, but resting on its anaphoric behaviour spanning intensional operators. (shrink)

A puzzle about false judgement is raised in the Theaetetus (187d-200c), but not successfully answered there. On the proposed account, the confusion that explicitly vitiates Theaetetus’ final attempt to define knowledge is already at work implicitly in this puzzle. Theaetetus shares popular assumptions about knowledge (epistēmē), but also accepts that there are cognitive constraints on judgement (doxa): the puzzle arises because he fails to distinguish the one cognitive condition from the other.

Stoics and Sceptics distinguish belief (doxa) from a representationally and functionally similar but sub-doxastic state: passive yielding to appearance. Belief requires active assent to appearances, that is, affirmation of the appearances as true. I trace the roots of this view to Plato's accounts of doxa in the Republic and Theaetetus. In the Republic, eikasia and pistis (imaging and conviction) are distinguished by their objects, appearances versus ordinary objects; in the Theaetetus, perception and doxa are distinguished by their objects, proper perceptibles (...) versus ‘commons’, including being. But underlying these ontological distinctions is a psychological one: the lower mental states are confined to their lower objects because they are passive; the higher mental states have access to higher objects because they result from questioning appearances and making active affirmations about how things are. This doctrine of doxa anticipates both the Hellenistic one and modern accounts of belief as ‘aiming at truth’; it also shows Plato's views of doxa to have more in their favour philosophically and to cohere better with one another than generally thought. (shrink)

This paper argues for the presence in Plato’s work of a conception of thinking central to which is what I call the Transparency View. According to this view, in order for a subject to think of a given object, the subject must represent that object just as it is, without inaccuracy or distortion. I examine the ways in which this conception influences Plato’s epistemology and metaphysics and explore some ramifications for contemporary views about mental content.

Two readings of the much-discussed περιτροπή argument of "Theaetetus" 170c-171c have dominated the literature. One I call "the relativity reading". On this reading, the argument fails by ignoratio elenchi because it "carelessly" omits "the qualifications 'true for so-and-so' which [Protagoras'] theory insists on" (Bostock 1988: 90). The other reading I call "the many-worlds interpretation". On this view, Plato's argument succeeds in showing that "Protagoras' position becomes utterly self-contradictory" because "he claims that everyone lives in his own relativistic world, yet at (...) the same time he is forced by that very claim to admit that no one does" (Burnyeat 1976b: 48). I discuss and criticise both readings, and present a third, according to which the point of the argument is, very roughly, that Protagoras is committed to equating truth and truth-for, and so, further, to their intersubstitutability. This further commitment proves fatal to his argument. (shrink)

In this paper I discuss the dialogues between 'Protagoras', Theodorus and Socrates in "Theaetetus" 161-171 and emphasise the importance for this passage of a dilemma which refutation is shown to pose for relativism at 161e-162a. I argue that the two speeches delivered on Protagoras' behalf contain material that is deeply Socratic and suggest that this feature of the speeches should be interpreted as part of Plato's philosophical case against relativism, reflecting the relativist's own inability to defend his theory from attempts (...) to refute it. I then discuss Theodorus' role in the refutation of Protagoras and argue that his voice is needed to get relativism disproved in the self-refutation argument of 171a-c. I conclude with a brief discussion of the image of Protagoras at 171d. (shrink)

This paper is a test case for the claim, made famous by Myles Burnyeat, that the ancient Greeks did not recognize subjective truth or knowledge. After a brief discussion of the issue in Sextus Empiricus, I then turn to Plato's discussion of Protagorean views in the Theaetetus. In at least two passages, it seems that Plato attributes to Protagoras the view that our subjective experiences constitute truth and knowledge, without reference to any outside world of objects. I argue that these (...) passages have been misunderstood and that on the correct reading, they do not say anything about subjective knowledge. I then try out what I take to be the correct reading of the passages. The paper concludes with a brief discussion of the importance of causes in Greek epistemology. (shrink)

In this paper I explore 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 are to solve some puzzles about how it is possible to make a mistake. On my interpretation, defended here, the discussion of mistakes is no digression, but is part of the refutation of Theaetetus’s thesis that knowledge is “true doxa”. It reveals that false doxa (...) is possible only if there is a certain stock of abstract knowledge, conceptual knowledge, that is not awareness of the particular individual that is being described. The individual must be identified under some description, or seen as something of a certain kind. Error can only occur if the description applied misdescribes the situation, but then if it is to be applied falsely it must first have been known from somewhere else. So 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 on the ground. (shrink)

With the use of a particular metaphor, which appears at the end of the Cratylus and is taken up with perfect symmetry at the beginning of the Theaetetus, Plato certainly wanted to indicate the succession of Cratylus–Theaetetus as an order for reading the two dialogues, which Trasillus faithfully reproduced in structuring the second tetralogy of Platonic dialogues. The claim of the theory of ideas, with which the Cratylus ends, must therefore be considered the background in which to place not only (...) the analysis of the name carried out in the Cratylus, but also the discussion and criticism of the epistemological theories examined and refuted in the Theaetetus. The transition from the discussion of the name to that of the logos is another important theoretical element that connects the two dialogues. Another one is the theory of knowledge, already precisely elaborated in the Cratylus, and taken up and deepened in the Theaetetus. Finally, the theme of false and error is a third theoretical element common to the two dialogues, which, starting from Euthydemus, finds its solution in the Sophist. (shrink)

Two readings of the much-discussed περιτροπή argument of "Theaetetus" 170c-171c have dominated the literature. One I call "the relativity reading". On this reading, the argument fails by ignoratio elenchi because it "carelessly" omits "the qualifications 'true for so-and-so' which [Protagoras'] theory insists on" (Bostock 1988: 90). The other reading I call "the many-worlds interpretation". On this view, Plato's argument succeeds in showing that "Protagoras' position becomes utterly self-contradictory" because "he claims that everyone lives in his own relativistic world, yet at (...) the same time he is forced by that very claim to admit that no one does" (Burnyeat 1976b: 48). I discuss and criticise both readings, and present a third, according to which the point of the argument is, very roughly, that Protagoras is committed to equating truth and truth-for, and so, further, to their intersubstitutability. This further commitment proves fatal to his argument. (shrink)

Nel nostro universo, qualunque cosa, dalla più piccola particella alla più smisurata galassia, esiste in un qualche tempo e in un qualche luogo. Ma cosa significa esistere in un qualche tempo? Il fenomeno dell’esistenza temporale gioca un ruolo fondamentale nella comprensione dell’universo e di noi stessi quali creature temporali. Eppure è un fenomeno profondamente misterioso. L’esistenza temporale è da intendersi come una relazione? Che legami ha con l’esistenza dell’ontologia? L’esistenza temporale e la localizzazione spaziale sono due fenomeni essenzialmente differenti o (...) due istanze di un’unica relazione? Tutto ciò che esiste nel tempo esiste nel tempo nello stesso modo? Tutto ciò che è nel tempo è anche nello spazio? (shrink)

En su defensa del Principio de no-contradicción, Aristóteles discute con varios interlocutores, desde los presocráticos hasta el sofista Protágoras, este último ampliamente conocido en la Antigüedad por trastocar el concepto de verdad con su doctrina del “homo mensura”, declarando así la imposibilidad del discurso falso. Consideramos que una lectura atenta del Libro Γ que rescate la figura del abderita puede mostrar cómo la crítica del sofista es clave para la constitución del pensamiento aristotélico en torno al problema de la verdad. (...) En la primera sección expondré algunas consideraciones sobre el PNC que son relevantes para entender las motivaciones detrás de las críticas aristotélicas al sofista. A continuación, analizaré dos de los argumentos aristotélicos contra los adversarios que discuten de mala fe: por una parte, la “refutación” de Metaph. Γ. 4 y, por otra parte, el “argumento de las apariencias contrarias” de Metaph. Γ. 5. Mi hipótesis es que algunos elementos teóricos esbozados en Γ. 4 permiten reconstruir una crítica aristotélica seria contra Protágoras en Γ. 5. Finalmente expondré una síntesis del camino recorrido y ofreceré algunas conclusiones. (shrink)