Abstract

Hylomorphism is the Aristotelian theory according to which substances are composed of matter and form. If a house is a substance, then its matter would be a collection of bricks and timbers, and its form is something like the structure of those bricks and timbers. It is widely agreed that matter bears a mereological relationship to substance; the bricks and timbers are parts of the house. But with form things are more controversial. Is the structure of the bricks and timbers best conceived as a part of the house, or is it related to the house in some non‐mereological fashion? Kathrin Koslicki argues that substances have formal parts and that forms are best conceived as bearing a mereological relation to substances. This paper shows that her argument fails, given the traditional and plausible distinction between substances and accidental unities. I close with a brief suggestion for a non‐mereological construal of forms.