在政治理論裡的三種不同的對於自由的理解當中，消極自由無疑居於最核心之主軸地位，但其他兩種自由觀（亦即積極自由與共和主義式自由）亦有其不容輕忽之意義。艾賽亞．伯林對消極自由的申辯固然有振聾發聵之效，但若能借助積極自由與共和主義式自由之正面元素，當能使民主社會裡之自由處境更臻善境。本文試圖指出，消極自由、積極自由以及共和主義式自由並不是存在於同一個平面或層次，而是各自指涉著不同的平面與層次。易言之，其彼此之關係並不是同一個平面或層次裡的零和關係，亦不是一者之增長必造成另一者之損失或萎縮。相反地，注重共和主義式自由，才能使消極自由更得以被有效確保；而重視個體意義下的積極自由，則更能深化消極自由之實質內涵。亦即，積極自由以及共和主義式自由實可做為消極自由之內部的及外部的輔助機制。

Liberty is without doubt one of the fundamental political values in modern political life. The lack of liberty not only threatens tremendously the legitimacy of a polity, but also diminishes the desirability of living in it. Though a good in itself, liberty is until now a concept without a precise definition that everyone agrees with. On the contrary, there are at least three major understandings of it in political theory, i.e., negative, positive and republican liberty. This article compares the distinctness of these liberties and examines the possible connections among them, with the hope of providing a better theoretical insight into finding a firmer ground upon which a more heuristic human interaction could stand. Finally, this article also endeavors to defend negative liberty in its individual sense, which Isaiah Berlin, though with good intent, has crudely and unconvincingly suppressed in his famous dichotomy of liberty.