Pyrrhonian scepticism and epistemic relativism have both been attacked as self-undermining positions. This charge can be spelled out by presenting sceptics and relativists with the following dilemma: if your conclusion is true, then it cannot be defended, and if it is false, then it is not worth defending. In the sceptic's case, if it is true that we cannot possess knowledge, then we cannot know that this is the case, and if it is false, then we should reject scepticism. In the relativist's case, if it is true that no knowledge claims admit of absolute justification, then we cannot be absolutely justified in knowing this to be so, and if it is false, then we should reject epistemic relativism. The aim of this chapter is to show that sceptics and relativists can accept the first horn of the dilemma without rendering their conclusions indefensible or their positions incoherent.