One way of developing a sceptical position is to take some hypothesis (H) which entails the sceptical thesis (T) that nothing is known, and argue that since H is not known to be false, T cannot be known to be false either. That is, since His not known to be false, it is not known that anything is known. One may then argue convincingly that no one knows anything at all (T) on the grounds that it is not known that anything is known is virtually equivalent to nothing is known (sc. that knowing is virtually equivalent to knowing that one knows). Take, for example, the Cartesian sceptical hypothesis that there is an evil demon systematically deceiving everyone all of the time about everything. Instead of arguing that the hypothesis is true and that there actually is such a creature, it is much more plausible to suggest that no one knows for certain that there is not, so that in this sense it is possible that there is. What follows is not that no one knows anything, but that it is not known that anything is known.