In theTreatise, Hume wrote that sceptical doubts “arise naturally” from careful philosophical investigation and claimed, albeit ironically, that “carelessness and in-attention alone can afford us any remedy.”¹ I do not believe that he was correct; and the goal of this book is to show that scepticism is implausible by carefully examining the epistemic principles upon which it is based.

Aside from the philosophically unsatisfactory “remedy” for scepticism mentioned by Hume, there are two initially attractive methods often employed in attempting to demonstrate the implausibility of scepticism. The first is to reject scepticism merely because it conflicts with the supposedly...

The task of this chapter is to examine arguments for Direct Scepticism: that is, arguments designed to show that no S can have knowledge that p, where ‘p’ stands for some empirical proposition which we normally believe is knowable. The number of these arguments is legion; and we cannot examine all of them. But one constantly re-emerges as the last-ditch stand of the Direct Sceptic—it is the Evil Genius Argument. It has been recast for modern readers in the guise of a group of godawful googols, mad scientists equipped with super-computers and vats which contain brains, or other malevolent...

It seems best to begin this chapter by reviewing the role it is to play in the proposed refutation of scepticism. Briefly, the aim here is to delineate an account of absolute certainty which both captures all the intuitively plausible features of the sceptic’s insistent claim that knowledge entails absolute certainty and is such that many “ordinary,” empirical contingent propositions are, in fact, absolutely certain.

In order to more fully understand the importance of the role of this chapter, let me restate the overall argument of this book, indicating what I believe has already been accomplished and what remains to...

This final chapter will be mercifully brief. For I merely wish to recall the goal and the general strategy of this book and show that we have, in fact, accomplished the task. Recall that the purpose was to show that three significant forms of scepticism are implausible. Those three varieties of scepticism are:

Direct Scepticism It is not the case that S can know that p.

Iterative Scepticism It is not the case that S can know that S knows that p.

Pyrrhonian Direct Scepticism There are no better reasons for believing that S can know that p than there...