About

Tad Brennan is a Professor in the Department of Classics at Cornell University. His academic interests focus on Greek Literature and Ancient Philosophy, with a primary emphasis on Plato and Aristotle. He also studies the Stoics, Skeptics, Epicureans, Pre-Socratics, and late Platonists. Brennan's research involves exploring various aspects of Ancient Greek philosophical thought, including ethics, epistemology, and the interpretation of classical texts. He has authored several publications, including books such as 'The Stoic Life: Emotions, Duties, and Fate' and 'Ethics and Epistemology in Sextus Empiricus.' Brennan has contributed chapters to scholarly collections on Stoic moral psychology and the emotions in Hellenistic philosophy, and has written articles on topics like Sextus Empiricus, Anaxagoras, and Pyrrho. His work is accessible through his Academia.edu profile, where he shares papers, chapters, and reviews. Brennan teaches courses on Greek and Roman Philosophy, Hellenistic Philosophy, and Greek Philosophical Texts at Cornell University. His academic career is dedicated to the study and teaching of classical philosophy, with a focus on understanding the ethical, metaphysical, and epistemological ideas of ancient Greek philosophers.

Research topics

• Philosophy
• Epistemology
• Computer Science
• Physics
• Psychology
• Art
• Psychoanalysis
• Mathematics
• Literature
• Linguistics

Selected publications

• 1 Cephalus, patêr tou logou

  Edinburgh University Press eBooks · 2025-05-04

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• The Role of Magnitude in Stoic Emotions

  Cambridge University Press eBooks · 2025-09-11

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• Cephalus, patêr tou logou

  Phronesis · 2022

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  • Philosophy
  • Epistemology

  Abstract I argue that Cephalus introduces the argumentative paradigm of the entire Republic , the Challenge of Glaucon and Adeimantus, through his comments on wealth and his story about Themistocles.

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• Reading Plato’s Mind

  Oxford University Press eBooks · 2020

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  • Computer Science
  • Epistemology
  • Psychology

  Abstract This chapter distinguishes two Platonic interests in self-knowledge: the ‘thin’ self-knowledge that a human being is a rational soul using its body as a tool (the Delphic self-knowledge made prominent in the Phaedrus, First Alcibiades, and elsewhere), and the ‘thick’ self-knowledge of the particular accidental psychological profile of an individual. The two are contrasted in four ways: the thin applies to the entire species, makes no reference to irrational parts, offers no etiology of contingencies, and makes no special use of first-personal knowledge; the thick applies to individuals, incorporates details about the irrational soul, explains the individual through a narrative of the events that shaped them, and is first-personal in making the object of self-knowledge identical with the subject of that self-knowledge. This richer, thicker form of self-knowledge is illustrated with extensive examples from the Republic and Seventh Letter.

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• Forms, Platonic

  2018-09-11

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  Plato thought that in addition to the changeable, extended bodies we perceive around us, there are also unchangeable, extensionless entities, not perceptible by the senses, that structure the world and our knowledge of it. He called such an entity a ‘Form’ (eidos) or ‘Idea’ (idea), or referred to it by such phrases as ‘the such-and-such itself’. Thus in addition to individual beautiful people and things, there is also the Form of Beauty, or the Beautiful Itself. It may be speculated that Plato’s Presocratic predecessors gave some impetus to this theory. It is a certainty that Socrates was the major influence on it, through his search for the definitions of ethical terms. The features that a definition must have in order to satisfy Socrates’ criteria of adequacy foreshadow the features that Forms have in Plato’s theory. Beginning with his Meno, Plato turned his attention to the presuppositions of Socrates’ investigation, and the preconditions of its possibility: what has to be true about virtue, knowledge and our souls if Socratic cross-examination is to have any hope of success? He answers these questions with a set of doctrines – the existence of Forms, the soul’s immortality and its knowledge of Forms through recollection – which are then developed and displayed in the great dialogues of his middle period, the Phaedo, Symposium, Phaedrus and Republic. Not all of Plato’s thoughts on Forms are on display in the middle-period theory, but this is the theory of Forms that has been far and away the most influential historically, and the one that is most commonly intended when people refer to ‘Plato’s Forms’. The dialogues of Plato’s later period present a number of puzzles. That his views developed will be agreed by all: in the Sophist, Statesman and Philebus Plato is clearly pushing his metaphysical investigations in new directions. What is less clear is the degree of continuity or rupture between old and new – the Parmenides has sometimes been taken to signal Plato’s wholesale rejection of the middle-period theory, whereas the Timaeus seems to confirm his endorsement of it. Further complicating matters, Aristotle reports that Plato in his last period based the Forms somehow on numbers. The reported material is obscure in itself and also hard to integrate with any of the material from Plato’s dialogues. Much of our current understanding of Plato’s middle-period theory comes from a group of arguments that advert to differences between Forms and sensible objects or properties. These arguments tend to support Aristotle’s report that the theory arose from a collision between Socrates’ views on definition and Heraclitean views on flux. The general form of the argument claims that definitions, or knowledge, require the existence of a class of entities with certain features, and that sensibles lack those features. It concludes that there exists a class of entities distinct from the familiar sensibles, namely the Forms. But as often in historical studies, the arguments themselves are silent or ambiguous on many of the points that critics most wish to determine: whether Plato thought Forms exist separately from particulars, whether he treated them as Aristotelian substances, whether it is possible to have knowledge of sensible objects, whether Plato came to reject the middle-period theory, and so on. For the second half of the twentieth century, the tendency was for interpreters to settle the remaining interpretative issues by ascribing to Plato their own philosophical preferences, justifying this by appeal to ‘interpretative charity’. The practice of basing interpretations of Plato’s Forms solely on a handful of arguments was a mistake; the increasing tendency to broaden the evidentiary base is a salutary development. Where the interpretation of an argument has left a question unresolved, the consideration of Plato’s myths and metaphors may sometimes lend strong weight to one side or the other. An example: Plato’s depictions of particulars make it highly implausible that the ‘imperfection’ in particulars to which some arguments advert is merely the compresence of opposites. Most of Plato’s successors in the early Academy kept up the Forms. Aristotle’s writing are full of references to them, and they left visible imprints on his own theory. The Hellenistic period witnessed a blanket rejection of all immaterial entities, but even here the influence of the Forms can still be discerned around the edges. The revival of Platonism at the end of the Hellenistic period saw Forms returned to philosophical respectability.

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• Technē

  2018-09-11 · 2 citations

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  Technē (plural technai) is the ancient Greek term for an art or craft; examples include carpentry, sculpting and medicine. Philosophical interest in the technai stems from their use as a model and metaphor for all aspects of practical rationality, including its perfection in philosophy (the ‘art of living’). From Socrates onwards, the notion of technē is employed for thinking about the connections between reason, ends and action. Technai are held to possess epistemological virtues (such as coherence and explanatory power) and practical virtues (their delivering of detailed instructions for action) against which other bodies of belief or practical systems can be studied and judged.

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• Immortality in ancient philosophy

  2018-09-11 · 1 citations

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  In Greco-Roman philosophy immortality is discussed in two contexts: as an uncontroversial attribute of the gods and as a highly controversial attribute of human souls. Subdividing this latter topic, one may discern a more metaphysical question about whether every human soul as such is immortal in virtue of its nature or essence, and a more ethical topic about whether certain souls may enjoy a greater degree or share of immortality through adopting a certain mode of life. (This sub-topic is joined to the first main topic, to the extent that the virtuous agent’s approximation to immortality is part of their imitation of god or homoiōsis theōi). Several Presocratic philosophers held that human souls are immortal, but it is Plato who first offers extensive arguments for this claim, as well as extensive reflections on the ethical import of personal immortality. Aristotle’s psychology leaves little room for the soul’s immortality, and it remains controversial whether he wished to leave any whatsoever. Discussions of immortality and its ethical consequences are similarly downplayed in surviving Stoic sources. The Epicureans gleefully argued the contrary view that a virtuous outlook depends on our conviction that we are irredeemably mortal. Only with the resurgence of Platonism in the Common Era does the soul’s immortality become once again a commonplace among philosophers. The connection between this and the Christian belief in resurrection is complicated. It is presumably due to the ascendancy of this double legacy that current popular usage counts it as nearly tautological that souls are immortal, but acknowledges a real question of whether human beings have souls, where ancient usage accepted as a near tautology that all living beings have souls, but admitted wide dispute over whether souls are immortal or not.

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• Telos

  2018-09-11

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  Telos is the ancient Greek term for an end, fulfilment, completion, goal or aim; it is the source of the modern word ‘teleology’. In Greek philosophy the term plays two important and interrelated roles, in ethics and in natural science; both are connected to the most common definitional account of the telos, according to which a telos is that for the sake of which something is done or occurs. In ethical theory, each human action is taken to be directed towards some telos (i.e. end), and practical deliberation involves specifying the concrete steps needed to attain that telos. An agent’s life as a whole can also be understood as aimed at the attainment of the agent’s overall telos, here in the sense of their final end or summum bonum (‘highest good’), generally identified in antiquity as eudaimonia (happiness). Rival ancient ethical theories are distinguished primarily by their rival specifications of the end; the Epicurean telos is pleasure, the Stoic telos is life according to nature, and so on. In the natural science of Aristotle, the telos of a member of a species is the complete and perfect state of that entity in which it can reproduce itself (so, insects reach their telos when they become adults). The telos of an organ or capacity is the function it plays in the organism as a whole, or what it is for the sake of; the telos of the eye is seeing. Carrying on the tradition of Anaxagoras and Plato, Aristotle centres his scientific methodology around the claim that there are ends in nature, i.e. that some natural phenomena occur for the sake of something; Galen and the Stoics enthusiastically second this; Epicurus rejects it.

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• The Psychological Import of the First Wave in <i>Republic</i> 5

  Cambridge University Press eBooks · 2017-12-12 · 1 citations

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  A summary is not available for this content so a preview has been provided. Please use the Get access link above for information on how to access this content.

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• A MILD REMEDY FOR A MILD DISEASE: THE TEXT OF <i>REPUBLIC</i> 459B

  The Classical Quarterly · 2016-07-29

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  Here's a fine argument for you! 1) Anyone who plans to prescribe medicines will need to be a skilled doctor ; 2) These people plan to prescribe medicines ; 3) Therefore, these people will need to be skilled rulers . If you expected the last word of the conclusion to be ‘doctors’ instead of ‘rulers’, then you will find the rest of this note plain sailing.

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Frequent coauthors

• Charles Brittain

  8 shared

• Keimpe Algra

  Utrecht University

  4 shared

• Brad Inwood

  3 shared

• R. J. Hankinson

  The University of Texas at Austin

  3 shared

• Rachel Barney

  University of Toronto

  3 shared

• Susanne Bobzien

  University of Oxford

  2 shared

• G. F. Woods

  1 shared

• Paul Oskar Kristeller

  Columbia University

  1 shared