If updating with E has the same result across all epistemically possible worlds, then the agent has no uncertainty as to the behavior of the update, and we may call it a transparent update. If an agent is uncertain about the behavior of an update, we may call it opaque. In order to model the uncertainty an agent has about the result of an update, the same update must behave differently across different possible worlds. In this paper, I study opaque updates using a simple system of dynamic epistemic logic suitably modified for that purpose. The paper highlights the connection between opaque updates and the dynamic-epistemic principles Perfect-Recall and No-Miracles. I argue that opaque updates are central to contemporary discussions in epistemology, in particular to externalist theories of knowledge and to the related problem of epistemic bootstrapping, or easy knowledge. Opaque updates allow us to explicitly investigate a dynamic (or diachronic) form of uncertainty, using simple and precise logical tools.

如果用E更新在所有认识上可能的世界中具有相同的结果，则该代理对更新的行为没有不确定性，我们可以称其为透明更新。如果代理不确定更新的行为，我们可以称其为不透明。为了建模代理对更新结果的不确定性，同一更新必须在不同的可能世界中表现不同。在本文中，我研究了使用针对此目的进行了适当修改的动态认知逻辑的简单系统来进行不透明更新。本文强调了不透明更新与动态流行原理“完美召回”和“无奇迹”之间的联系。我认为，不透明的更新是当代认识论讨论的核心，尤其是外在的知识论和认识论引导的相关问题，或简单的知识。不透明的更新使我们能够使用简单而精确的逻辑工具来明确地研究动态（或历时性）不确定性形式。