The Surprise Exam Paradox is well‐known: a teacher announces that there will be a surprise exam the following week; the students argue by an intuitively sound reasoning that this is impossible; and yet they can be surprised by the teacher. We suggest that a solution can be found scattered in the literature, in part anticipated by Wright and Sudbury, informally developed by Sorensen, and more recently discussed, and dismissed, by Williamson. In a nutshell, the solution consists in realising that the teacher's announcement is a blindspot that can only be known if the week is at least 2 days long. Along the way, we criticise Williamson's own treatment of the paradox. In Williamson's view, the Surprise is similar to the Paradox of the Glimpse and, because of their similarities, both these paradoxes ought to receive a uniform treatment—one that involves locating an illicit application of the KK Principle. We argue that there's no deep analogy between the Surprise and the Glimpse and that, even if there were, the Surprise reasoning reaches a paradoxical conclusion before the KK Principle is used. Rather, in both the Surprise and the Glimpse, the blame should be put on other epistemic principles—respectively, a knowledge retention and a margin for error principle.

中文翻译：

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惊喜啊惊喜：KK是无辜的


突击考试悖论是众所周知的：一位老师宣布下周将有一场突击考试；学生们凭直觉合理地论证说这是不可能的；然而，他们可能会对老师感到惊讶。我们建议可以在文献中找到一种解决方案，部分是由赖特和萨德伯里预见的，由索伦森非正式开发的，最近由威廉姆森讨论和驳回。简而言之，解决方案在于认识到老师的公告是一个盲点，只有当一周至少有 2 天时才能知道。一路上，我们批评威廉姆森自己对悖论的处理方式。在威廉姆森看来，惊奇与一瞥悖论相似，并且由于它们的相似性，这两个悖论都应该得到统一的处理——其中包括找出 KK 原则的非法应用。我们认为，惊奇与一瞥之间没有深刻的类比，即使有，惊奇推理也会在使用 KK 原理之前得出一个矛盾的结论。相反，在“惊奇”和“一瞥”中，责任应该归咎于其他认知原则——分别是知识保留和错误裕度原则。