Some contemporary philosophers in the Aristotelian tradition contend that agents differ from non-agents in that the former possess and exercise two-way causal powers.1 According to this distinction, non-agents possess powers that have only one type of manifestation. The powers of agents, by contrast, are manifested in two distinct and opposed ways.2 In developing this account, two-way powers theorists explicitly draw on Aristotle’s distinction between rational and non-rational powers in Metaphysics Θ.2 and 5 (see, e.g., Alvarez, 2009, p. 72, n. 16, 2013, p. 109; Steward, 2020, pp. 352–4; Frost, 2020, pp. 1148–1151). Proponents of this approach disagree about the nature of the two ‘ways’ in which agents manifest their agency (see especially Frost, 2020, and Steward, 2020). There is accordingly disagreement about how we should understand the Aristotelian ideas that anticipate the relevant notion of a two-way power (§§2–3). Nevertheless, all parties seem to agree on this much: a two-way causal power is a single power that directly relates to two distinct and opposed ways in which matters might proceed (see Alvarez, 2013, p. 102; Steward, 2012, p. 155; Lowe, 2013, p. 177; Frost, 2020, p. 1148).