 (iii) Action. If skeptics suspend judgment, argues their dogmatic opponent, they are not able to act. Stoic philosophy conceives of three movements of the mind: impression, assent, and impulse (Plutarch, Col. 1122a-d). All three figure in action. The agent assents to the impression that A is to be done; their assent is an impulse for the action A; if there is no external impediment, the impulse sets off the action (Inwood 1985). It is a cornerstone of Stoic philosophy that there can be no action without assent, and so without the belief that the action done is to be done. The Stoics aim to avoid the kind of determinism according to which actions are not ‘up to’ the agent (Bobzien 1998); for them, assent, but not impression, is up to the agent. In response to the Apraxia Charge, Arcesilaus seems to have argued that the skeptic can act without having assented (Plutarch, Col. 1122A-d), and so without believing that the action done is to be done. However, this is not his complete response. From the point of view of the Stoics, skeptical action, if performed without the relevant kind of assent (that is, assent that it is up to the agent to give, and that is a rational acceptance of the impression), is like the action of a non-rational animal, or like the automatic movement of plants when they grow and flourish. Arcesilaus is robbing people of their minds (Cicero Acad. 2.37–9; Obdrzalek 2013). But Arcesilaus need not and does not go so far as to compare human agents with non-rational agents. As human beings, skeptics have rational impressions. They perceive the world conceptually, and think about it. Arcesilaus does not suggest that skeptical action is causally set off by impressions, or in the way, whatever that is, that animal actions are set off. This would be a problematic proposal, for it would disregard that the skeptic has a human mind. Given the complexity of human thought, the skeptic is likely to have several, and often competing impressions. If all impressions triggered impulses, the skeptic would be inactive due to a kind of paralysis. The second component of Arcesilaus’ reply, thus, is that the skeptic, in acting without assenting, adheres to the reasonable (eulogon) (SE M 7.158; 7.150; Striker 2010). That is, Arcesilaus aims to explain skeptic action as rational agency (Cooper 2004b). Arcesilaus disputes the dogmatic claim that some impressions can be identified as true, and the related claim that one can only act on the belief that some impression is true. But he does not argue that there are no differences between impressions which agents could take into account. His agents are rational: they think about their options, and go with what looks, in one way or another, more plausible.