公共哲學是一個晚近學界討論的關鍵字，本篇論文考察出它可能蘊含的三種概念，分別是公共事務的哲學、大眾哲學，以及理性的公開運用。這三個概念雖然有所區分，但是在現實的使用中經常是混雜與並存的，並非全然互斥。本論文接著從理性的公開運用切入，探討臺灣的公共哲學的實踐，尤其是近二十年的沙龍文化，並以「哲學星期五」此一公共論壇為考察的個案。本論文認為，在現今社群媒體的時代下，激情衝突與冷漠無感會促進政治極化的危機，進而造成民主內部的自我崩解，因此，公共哲學更顯現其實踐的重要性。

In this paper, I investigate three distinct concepts of public philosophy: philosophy of public affairs, popular philosophy, and the idea of public use of reason. These three concepts are partially related and not mutually excluded. I focus on the idea of public use of reason and investigate its practice in Taiwan’s recent social context. In the past twenty years, a public forum (salon) called “Philosophy on Friday” is gaining traction, which I argue, is an example par excellence of the idea. I also argue that in the age of democratic infighting and polarization, public philosophy may be part of the solution to the crisis.