The Illusion of Doubt shows that radical scepticism is an illusion generated by a Cartesian picture of our evidential situation—the view that my epistemic grounds in both the ‘good’ and the ‘bad’ cases must be the same. It is this picture which issues both a standing invitation to radical scepticism and ensures that there is no way of getting out of it while agreeing to the sceptic’s terms. The sceptical problem cannot, therefore, be answered ‘directly’. Rather, the assumptions that give rise to it, need to be undermined. These include the notion that radical scepticism can be motivated by the ‘closure’ principle for knowledge, that the ‘Indistinguishability Argument’ renders the Cartesian conception compulsory, that the ‘New Evil Genius Thesis’ is coherent, and the demand for a ‘global validation’ of our epistemic practices makes sense. Once these dogmas are undermined, the path is clear for a ‘realism without empiricism’ that allows us to re-establish unmediated contact with the objects and persons in our environment which an illusion of doubt had threatened to put forever beyond our cognitive grasp.

怀疑的错觉表明激进的怀疑主义是由笛卡尔对我们的证据情况的描述所产生的一种幻觉——即我在“好”和“坏”案例中的认知基础必须相同的观点。正是这张图既向激进的怀疑主义发出长期邀请，又确保在同意怀疑论者的条件的同时没有办法摆脱它。因此，怀疑问题不能“直接”回答。相反，需要破坏产生它的假设。其中包括激进的怀疑主义可以由知识的“封闭”原则激发的概念，“不可区分性论证”使笛卡尔概念成为强制性的，“新邪恶天才论点”是连贯的，以及对“全球验证”的需求'我们的认知实践是有道理的。