 Skepticism about the existence of artifacts goes back at least to Aristotle. For him, the primary existents are substances—independent things on which all other things depend. Individual things, such as horses or houses, are compounds of matter and form, but it is not entirely clear whether the substance of the thing is the form, the matter, or the compound (Shields 2022). That said, Aristotle is clearly ambivalent as to whether artifacts have what it takes. In the Physics (192b8–39), for instance, he says that some things, such as chipmunks or geraniums, exist by nature and that each such thing is a substance. He follows this up in the Metaphysics (1043b15–25), saying that perhaps only such things as exist by nature are substances, thus implying that things made by art, such as pots or pincushions, are not. Exactly why Aristotle thinks artifacts are not substances is not entirely clear—he suggests different reasons in different places (Katayama 1999, 18–19). But it is clear that he doubts that they really exist in the full sense enjoyed by things that exist by nature.