Law of Nations or Perpetual Peace? Two Early International Theories on the Use of Force

The law of nations (LN) and the perpetual peace projects (PPP). These two traditions emerged in the late 16th century and lasted until the Congress of Vienna, when their late developments gave rise to modern international law, on the one hand, and to international organizations and peace movements, on the other hand. Both the LN and the PPP influenced and were influenced by the emergence and growth of the modern states in Europe (and, progressively, outside the Old Continent) and tackled the question of how these new institutional entities should regulate their mutual relations. As a consequence, the main issue addressed by these two traditions was the question of war and, therefore, the achievement of peace. In considering the development of the LN and the PPP, we need to bear in mind that both these traditions arose and developed in transitional historical contexts, and often advocated changes that would take place in the following centuries.