A person who sincerely denies that the sun will rise tomorrow or that some trees are green is either a lunatic or a fool. And yet, skeptical arguments seem to show that such statements are doubtful. In this sense skeptical arguments seem to imply that we are not more rational than a lunatic or a fool. This is - in a nutshell - ‘the problem of skepticism.‘

Much of the history of philosophy may be interpreted as a series of attempts to get rid of this problem by discovering ways of justifying statements that most people take to be true as a matter of course.