中文：當代有關於外在世界的激進懷疑論者常利用知識封閉性原則去論證他們的立場。為了反駁這樣的懷疑論，有些學者主張我們應該重新檢視知識的標準，以便發現上述懷疑論論證中的問題，特別是知識封閉性原則是否成立的問題。這些學者中有兩類極為受到重視：一類是主張知識的成立與否只涉及「相關的」可能性的相關選擇理論學者，如D. Lewis、F. Dretske、和M. Heller，另一類則是主張知識的成立與否與某些虛擬條件有關的虛擬論者，如R. Nozic、E. Sosa、和K. DeRose。不幸的是，對於這兩類理論的討論往往流於直覺層面而缺乏邏輯的嚴謹性。為了彌補這個缺點，W. Holliday最近利用了兩種新的形式化語意論去重新模塑了上述兩類理論，並嚴格證明了每個理論在知識封閉性問題上的結果，他的形式化工作和證明帶來了極為嚴格而又豐碩的成果。本課程的主要目的便在對從Dretske以降的這一序列知識論討論做出充分的掌握。


英文：Contemporary skeptics about our knowledge of the external world typically argue for their position by appeal to the principle of knowledge closure. To respond to the skeptical challenge, some epistemologists propose that we need to re-examine our criterion of knowledge so as to expose problems of skepticism. This maneuver, in particular, has to do with whether the principle of knowledge closure is plausible or not. One approach concerns with the "relevant alternatives" proposal. Dretske, Lewis, and Heller are the main advocators. Another approach, advocated by Nozick, Sosa, and DeRose, concerns with whether and how the interpretation in terms of subjunctive conditionals is relevant to our theory of human knowledge. Unfortunately, the two approaches are typically based on mere intuitions and lack logical rigor. To remedy this, recently W. Holliday employs two new versions of formal semantics to re-shape the above two approaches. His work on the formalization and rigorous proofs provide us rich results. This course is to introduce and explain the development beginning from Dretske and up to Holiday.