Giles works on ancient philosophy (especially Plato and Aristotle), the philosophy of mind (esp. the emotions) and metaethics. His published work thus far has primarily focused on Aristotle's moral philosophy and philosophical psychology, although he has also published on Plato and contemporary metaethics.  He has published three books: two monographs, Aristotle on What Emotions Are, with Oxford University Press (2024), and Aristotle on Desire, with Cambridge University Press (2012); and an edited book (co-edited with Michael Pakaluk), Moral Psychology and Human Action in Aristotle, with Oxford University Press (2011).

Giles teaches undergraduate courses on Plato, Aristotle, aesthetics, and the emotions. At the graduate level, he has often taught an MA course on Value Theory and has supervised PhD work on metaethics. He is also available to supervise dissertations on ancient philosophy.