  The RNB view opens up a more promising way to read the brief counter-arguments in Plutarch and Sextus as a positive theory of Arcesilaus. His counter in Plutarch is that action isn’t always caused by occurrent beliefs—we sometimes act through habit, or by instinct. By itself, this doesn’t go very far, however, since the Stoics will have objected that, even if this were possible, this account couldn’t describe the voluntary and responsible actions of a rational agent. (The Stoics defined responsible or voluntary action in terms of assent, since this was the mechanism through which our rationality acts on the world.) But one can read the counter-argument in Sextus as supplementing that response: there is space for rationality and responsibility, on this view, in the production of the impressions or thoughts motivating us when we act. We can act in accordance with what strikes us as the reasonable thing to do upon reflection, but still refrain from assent, i.e., refrain from forming the belief that this is the right thing to do.