本文以樂生院保存運動做為思考的起點，探討都市規化理論中幾個重要課題，包括規化實踐的模式、公共利益的界定以及成是發展與文化保存之關係。本文首先回顧都市規劃專業的發展，並指出全盤理性規劃預設的公共利益所遭遇的困局。其次，本文借用多元公共領域的概念，提出多元公共利益的分析架構。第三，從多元公共利益角度，辨識不同團體對樂生院這個歷史性場所提出的都市論述，分析它們所公共利益，同時也說明它們對樂生院保存運動的影響。最後，研究者主張規畫專業者應依社會正義原則提出規劃策略，並正式新規劃時建與新規化主體的浮現。

This paper aims to discuss one of the most troublesome issues of urban planning in Taiwan: Do a city's development, expansion, and construction necessarily contradict the preservation of historical environments and community cultures? Tracing the epistemological foundation of urban planning, this paper suggests that the ignorance of cultures and disadvantaged groups by Taiwan's planning institutions results from its over-simplified understanding of the concept of public interest. Next, this paper analyzes the relation between public sphere and public interest and develops the concept of multiple public interests as an analytical framework to examine the contradiction between historic preservation and urban planning. Third, looking at the preservation movement of Taiwan Provincial Leprosarium, I points out the multiple spatial imaginations of this site held by various social groups and how these imaginations include or exclude certain public interests. Finally, I suggest that radical planner should propose planning strategies that conforms to the principles of social justice, and face up to the emergence of new planning practices as well as new planning subjects.