在都市計畫制定過程中，利益的不確定性和衝突時常阻礙了民眾參與的實踐，但即使克服該些阻礙，現行的民眾參與制度仍導向共同體成員（政府、實施者、所有權人）在追求自身最大利益下互相制衡之結果。然而，在考量都市計劃對外部環境和世代環境具備重大影響性下，實難論定該種結果能符合「公共利益」，此一議題突顯了在都市計劃中對於何謂「公共性」仍需再加探索。鑒此，本文重新檢視台灣都市計劃民眾參與之既有制度與文獻，歸納現行參與模式與理念，並識別具備公共性的民眾參與之實踐與理論的缺口；在此基礎上，本文引入康德對於「公共性」的轉向，即理性之公開運用，此有賴於公民的主動身分，在其利益和共同體利益無直接關係下，方能以普遍性法則作為行為決策所依據之法則，使其行為決策能如同「他者」作成之行為決策而具備普遍的公共性。因此，本文指出，民眾參與應納入無關共同體利益之空間和時間向度的他者之意見，此可透過隨機選擇引入參與者，並創造其需面對社會公眾之條件，以使其能夠代理他者之意見。最後，基於理論的反思和重建，為修復都市計劃的公共性及公共利益，本文對當前民眾參與制度之修正與未來公共參與模式之擘劃提供建議。

Uncertainty and conflict of interests often impede the practice of public participation in urban planning; nevertheless, even if overcoming the impediments, the current public participation institution still tends to bring about the outcome that members within the commonwealth (the government, the executor, and property owners) pursue their maximum interests with mutual restrictions. However, given the enormous impact of urban planning on the external and generational environment, the outcome should not be judged as agreeing with the “public interest.” This issue highlights that the content of “publicness” in urban planning needs further exploration. Therefore, this study reviews the existing institutions and literature of public participation in urban planning in Taiwan to deduce the current participation patterns and ideas and identifies the gap in the practice and theory of public participation with publicness. On the basis, this study introduces the Kantian shift in “publicness,” namely, the public use of reason, which relies on active citizenship without the direct relationship with commonwealth benefits, enabling decision-making to be based on universality and as others make to reach universal publicness. Thus, this study indicates that public participation should incorporate the opinions of others in spatial and temporal dimensions who are not involved in commonwealth benefits. This incorporation could be achieved by selecting participants randomly and bringing them the condition of facing the public to represent others’ opinions. Finally, through theoretical reflection and reconstruction, this study proposes suggestions on modifying the current public participation institution and rearranging the pattern of future public participation to restore publicness and public interest in urban planning.