What is an action? What do I mean when I say “I do something”? These are not questions that “philosophical” reasoning asks solely to satisfy its own curiosity; we come across them in our daily life. Imagine an utterly banal case: you are obliged to locate the source of a failure in the office; if you should say, “Well, regardless, you’re the one who did it,” you have made a judgment on these “philosophical” questions without intending to do so. In The World of the Middle Voice, published in Japan in 2017, Koichiro Kokubun endeavored to respond to these questions by means of an investigation into an ancient grammatical category of Indo-European languages: the middle voice. Proper names he referenced are Émile Benveniste, Aristotle, Dionysius Thrax, Jacques Derrida, Hannah Arendt, Spinoza, and Herman Melville, among others.