本文藉由對拉克勞與慕芙基進民主理論的探究，闡釋左翼民粹主義在其理論建構中，兩個特有的環節。一方面，作為政治本體論預設的對抗關係，無法轉化成任何具體的敵人形象，另一方面，在實體政治動態上的霸權形構，其效應是通過個殊元素對普遍性的佔位，而以競逐空位的方式來展現。這些理論構思同時也是對於當前自由民主現狀和左翼政治戰略的深刻反思，而分別在本體與實體層次上雙生的間隙，以及兩者之間立即的相互指涉，則讓左翼民粹主義有別於右翼民粹主義，這也回應了部分左翼民粹主義所引起的爭議。

The present article investigates the theory of radical democracy developed by Ernest Laclau and Chantal Mouffe, in hopes of elucidating two theoretical moments in left populism: antagonism and hegemonic formation. On one hand, as a political ontological assumption, antagonism as “the political” cannot be embodied by any concrete enemy. On the other hand, the effect of hegemonic formation in ontic political dynamics is represented by the taking up of universality by particular elements, in which various political forces compete in their efforts to present their particular objectives as those which carry out this filling function. In the theoretical conceptions of radical democracy, the double gaps emerging in ontological and ontic aspects and their immediate mutual reference make left populism totally different from right-wing populism.