Radical scepticism is the view that knowledge — most of it at any rate — is impossible. Strictly speaking it is not really a view, in that while there have historically been some people who have proposed such a position, its philosophical interest does not rest on whether there are any actual sceptics. The reason for this is that, properly expressed, radical scepticism is meant to be a paradox, in that it exposes a deep tension in our own epistemological concepts. Like all paradoxes, radical scepticism proceeds by identifying a series of claims that we would individually take to be highly intuitive, but which are shown to collectively entail an intellectually unacceptable conclusion — in this instance that knowledge is impossible. Since paradoxes are generated by our own concepts — in this case our epistemological concepts — it clearly doesn’t matter whether there is anyone out there who actually argues for the sceptical conclusion since it would still constitute a serious philosophical problem that we would need to deal with even if this were not the case.