Sean Kelsey works on ancient philosophy, especially Plato and Aristotle. He joined the faculty in 2025, receiving his BA from Thomas Aquinas College (1992) and his PhD in Philosophy from Princeton University (1997). Before coming to Chicago he had permanent appointments at Iowa State University (1997-98), UCLA (1998-2009), and the University of Notre Dame (2009-2025).
Selected Publications
Newman on the indefectibility of certitude: prolegomena to critical appraisal. In F. Aquino and J. Milburn, Newman and Contemporary Philosophy (Routledge, forthcoming), 63-83.
On Generation and Corruption II 11. In P. Dimas, A. Falcon, and S. Kelsey (eds.), Aristotle, On Generation and Corruption Book II. Introduction, Translation, and Interpretative Essays (Cambridge, 2022), 243-57.
Mind and World in Aristotle’s De Anima (Cambridge, 2021).
Limited government in Plato’s Republic. Philosophia 47 (2017), 50-70.
Empty words. In D. Ebrey (ed.), Theory and Practice in Aristotle’s Natural Science (Cambridge 2015), 199-216.
Truth and value in Plato’s Republic. Philosophy 88 (2013), 197-218.
Physics 199a8-12. Apeiron 44 (2011), 1-12.
Hylomorphism in Aristotle’s Physics. Ancient Philosophy 30 (2010), 107-24.
The argument of Metaphysics vi 3. Ancient Philosophy 24 (2004), 119-34.
Aristotle’s definition of nature. Oxford Studies in Ancient Philosophy 25 (2003), 59-87.
Recent Courses
PHIL 21727 Plato and his Predecessors
A close reading of Plato’s Hippias Major, Protagoras, and Gorgias. (A)
PHIL 55806 Aristotle’s Metaphysics Book Theta
A close reading of Aristotle’s Metaphysics Θ, along with Jonathan Beere’s Doing and Being. (III)
PHIL 25104/35104 Aristotle’s De Anima
A careful study of Aristotle’s De Anima in its entirety. (B)
PHIL 50275 Parmenides and the Origin of Metaphysics
Plato refers to him as "Father Parmenides"; even Aristotle grudgingly admits that discussing his views "offers scope for philosophy"; Hegel says that Parmenides "began Philosophy proper"; Heidegger describes him, together with Heraclitus, as "the founder of all thinking." In this course we will work through many of the remaining fragments of his poem, taking as our guide the wonderful new book by Matt Evans from which this course takes its title, Parmenides and the Origin of Metaphysics (Oxford, 2026).
PHIL 21728 Philosophy of Socrates: The Animating Spirit of Plato’s Socratic Dialogues
This course is about the Socrates of Plato’s dialogues: about his ‘philosophy,’ and about the man (the character) himself. We will approach these as two sides of the same coin (the character as embodying philosophy); both are paradoxical and elusive; we will try, not exactly to pin them down, but to enter into and develop a feel for them.
PHIL 23115/33115 Aristotle's Physics: Matter, Form, and Motion
In a way the course is text-oriented: our focus will be much of the first three books of Aristotle’s Physics. But the topics of these texts comprise a substantial portion of most anyone’s list of ‘Aristotle essentials’: his hylomorphism, definition of nature, theory of causes, chance and luck, natural teleology, nature and necessity, definition of motion. In addition to being a good introduction to a substantial portion of Aristotle’s ‘system,’ studying these texts will help develop facility in handling some of Aristotle’s philosophical vocabulary and distinctions. (A) (III)