Sceptics are troublemakers who can disrupt our position without having a coherent position of their own, by presenting us with considerations to which we cannot find a response that we find satisfying. If they are sick, they infect us with their sickness. Although some people have more natural immunity than others, probably few epistemologists feel no conflict at all within themselves between sceptical and anti-sceptical tendencies.

Timothy Williamson, ‘Knowledge and Scepticism’, in Frank Jackson and Michael Smith (eds.), The Oxford Handbook of Contemporary Philosophy, Oxford, 2005, p. 694