  On this view, the radical skeptic has beliefs but doesn’t take them to be justified. This proposal raises problems, too (see Burnyeat 1983). It seems that a large part of being a rational agent is to exercise some control over one’s beliefs. Since this control takes the form of a responsiveness to reasons, it does not seem possible for rational agents to give up practices of justification. A related objection is to maintain that even having beliefs, which involves the use of concepts, is necessarily responsive to reasons (see Williams 2004). To have a belief, according to this view, requires making a conscious inference about the proper use of concepts, and conscious inferences are made in virtue of reasons. One may respond that the skeptic isn’t precluding herself from a responsiveness to reasons but rather lacks confidence in them, and that such rationalist theories of agency and belief are stricter even than the Stoics’, against which Arcesilaus argued (see sect. 5 below).