貫徹殷海光一生最大的關懷是五四傳承的「德先生」（民主）與「賽先生」（科學），他的兩大西方影響源「自由主義」和「邏輯實證論」是兩個分別支持民主和科學的系統性理論。殷海光思想一個最重要的獨特面向是他對自由主義和邏輯實證論這兩大理論的整合，可使用「實證－自由主義」這一複合名詞來稱呼殷海光的整體思想。問題是，殷海光對兩大理論的整合到什麼程度？他成功了嗎？他的「整合」又是什麼樣的型態？本文回答這些問題。本文論證殷海光倡議的「邏輯實證論」並不是原汁原味的「邏輯實證論」，而是基於他的時代脈絡、基於他的公共參與和政治批判所塑造的「批判思考」實踐，構成他的自由主義觀點的一個重要的面向――這是本文對殷海光的自由主義的一個新詮釋：以「批判思考」的態度和方法為理論基礎的自由主義，亦可稱為「批判的自由主義」。

This paper aims to reconstruct and develop Yin, Haiguang’s “critical liberalism,” which means the integration of the classical liberalism with critical thinking founded by Yin, Haiguang during the 1950s-1960s. Transplanting Western democracy and science to China is the appeal of the May-Fourth Movement in 1919, which was inherited by Yin Haiguang. The spirit of the May-Fourth Movement, realizing democracy and science in China, came into his central concerns and became his ideal throughout his life. In order to realize his ideal, Yin had to search available and useful conceptual sources from the Western tradition of philosophy. He found that liberalism, being as a systematic theory for democracy, and logical positivism for science, could serve well for his goal. He thus introduced the two theories into Taiwan and contingently turned them into a coherent system. A unique characteristic of Yin’s achievement, in my view, is just his integration of liberalism and logical positivism. Yin systematically extracted some ideas out of logical positivism and applied them into the practice of critical thinking in political protests and comments. In doing such, he transformed the characteristics of logical positivism into a methodology of liberalism and thereby interweaved the ideas out of logical positivism with those out of classical liberalism. From this point of view, his liberalism is a “practical” type of liberalism based on critical thinking and public participation. I label Yin’s liberalism based on the integration as “critical liberalism.” Yin’s critical liberalism, reconstructed in this paper, consists of the following four theses: (1) Liberty or freedom is the human nature resisting all external oppressions. It is the inalienably fundamental rights of all human individuals. (2) Liberalism contains four aspects: political, economic, thoughtful, and ethic. Political freedom protects economic and thoughtful freedom; and thoughtful freedom is the basis of political freedom. (3) Democracy is a better institution for realizing political freedom. The attitude of critical thinking is the psychological basis of democratic practices. (4) Practicing critical thinking help strive for thoughtful freedom under a society without political freedom.