The liberal and republican traditions of political thought are commonly treated as divergent political-philosophical doctrines which existed in a state irreconcilable opposition in late eighteenth-century France and America. The present study challenges this notion through examining the concept of political neutrality as discussed and expounded in the political and constitutional writings of James Madison and Benjamin Constant. In seeking to account for not only why, but also how, both thinkers endeavoured to construct political systems geared toward securing the production of neutral laws, this thesis explores and highlights the complex interdependent relationship between the liberal and republican philosophical traditions in late eighteenth- and early nineteenth-century political theory. It is argued that in their desire to construct political-constitutional systems tailored toward guaranteeing the materialisation of neutral laws, Madison and Constant incorporated republican, or 'Real Whig', concepts into their respective constitutional strategies. Their shared objective, it is shown, was to form limited and neutral states through exploiting the diversity of public opinion in such a way that would render popular sovereignty self-neutralising. More specifically, this thesis suggests that both Madison and Constant placed considerable emphasis on de-legitimising particular justifications for legislative action, and that their respective efforts in this area were motivated by a desire to restrict the legislature to the promotion of objective, and impartially-conceived, accounts of the public good. Thus through examining Madison's and Constant's attempts to form neutral states, this thesis challenges the traditional account of the development of modern liberalism through pointing to the existence of an autonomous liberal-republican philosophy in post-revolutionary French and American political thought. It is argued that this hybrid political philosophy - which underpinned the constitutionalisms advanced by both Madison and Constant - had as its principal objective the reconciliation of the practice of popular governance with the restoration and maintenance negative individual liberty. Both thinkers, in other words, exploited republican concepts and institutions in order to realise the distinctly liberal end of forming limited and neutral states.