The democratic peace proposition has been lurking in Western thought for millennia, as Weart 1998 shows, but Kant 1991 provides its first modern formulation. The idea that global democracy would provide a solid foundation for global peace was restated in 1917 by Woodrow Wilson as a justification for American entry into World War I and then as part of his vision for a new world order. Modern political science first observed the dyadic democratic peace—that democracies tend not to fight each other—in the 1970s. The observation enjoyed greater attention in the 1980s in particular in two pathbreaking 1983 essays by Michael Doyle, reprinted in Doyle 2011 . It received fuller theoretical and empirical attention in the 1990s. Fukuyama 1992 , a famous argument that humanity had reached “the end of history,” incorporates the democratic peace proposition. Other scholars sought to develop the theory and push forward more advanced research designs in works such as Russett 1993 ; Ray 1995 ; and Rousseau, et al. 1996 . In the 2000s, proponents of the democratic peace responded to their critics and embedded the democratic peace in a broader Kantian peace ( Russett and Oneal 2001 ).