 It is necessary to separate some different threads in his argument here. First, there is something unnatural about the Cartesian strategy. Inquiries normally occur within a context: we address particular questions or problems, relying on background certainties that it does not occur to us to doubt. The Cartesian suggestion that we should begin by trying to doubt everything appears to be an attempt to step outside of this. Second, the Cartesian strategy requires us to reflect upon each of our beliefs and ask what reason we have for holding it; skeptical challenges are then used to question the adequacy of these reasons. This is again at odds with normal practice. Many of our familiar certainties are such that we cannot offer any concrete or convincing reason for believing them. We tend to treat our established beliefs as innocent until ‘proven guilty’. The mere lack of a conclusive reason for belief does not itself provide us with a reason for doubt.