Chapter 2 addresses Aristotle’s use of artefacts as counterexamples or central elements in counter-arguments against Plato and the Academy. The common opinion, within the Academy, that there cannot exist Ideas of artefacts is used by Aristotle to highlight the internal incoherence of the Platonic theory (Met. A 9, 990b8–15; Met. B 4, 999b15–20; Met. K 2, 1060b23–8). Moreover, the case of artefacts offers evidence that Ideas are either inert thus superflous (Met. A 9, 991b1–7; GC 2.9, 335b18–24), or even in contradiction with the coming-to-be of individual substances (Met. Z 8, 1033b19–24). The chapter shows that in these passages Aristotle is using artefacts dialectically against Plato’s separation of Ideas and concludes with a reflection on the notions of separation and substantiality.