Though sceptical arguments are very rarely judged to be persuasive, they are notoriously difficult to refute.

Perhaps the most straightforward attempt to refute philosophical scepticism is GE Moore’s appeal to common sense. Moore’s attempt begins with a simple argument: (1) Here is a hand, (2) Here is another, therefore (3) External objects exist. This argument may appear to be question-begging, but there is more to it than meets the eye.

Gilbert Ryle’s counterfeit coinage argument offers an alternative solution to the problem of scepticism. Ryle argues that scepticism, at least in its strongest forms, is incoherent. We can only make sense of the idea of false experience if there are also some true experiences to which they can be compared.

JL Austin’s linguistic argument is a response specifically to the argument from dreaming. That argument assumes that we cannot tell the difference between dreaming experiences and waking experiences. Austin argues that the fact that we use the phrase “a dream-like quality” shows that this assumption is false.

David Lewis’s contextualism makes a partial concession to scepticism. Contextualism suggests that the quality of evidence required for knowledge vary with context. Once sceptical doubts have been raised, it concedes, and the context changed, those doubts cannot be answered. This, however, doesn’t change the fact that in normal circumstances and by normal standards we do have knowledge.