The "democratic peace" theory is based on the observation that democracies hardly ever wage wars against one another. It is argued that this is due to the calculation of interests and the value orientation of the citizens of these states, and to the effects of democratic institutions. PRIF's former research program is committed to the democratic form of governance and accepts the basic premises of this theory. When one looks more closely at the evidence, however, contradictions start to appear which need to be examined and explained in more detail. It is true that democracies do not wage wars against each other, but they do engage in wars against undemocratic regimes, and they sometimes do this in particularly aggressive ways. In addition, democratization, the path leading to democratic peace, is often an especially violent process. And while international organizations can function as the institutional basis for peaceful cooperation, they also involve the risk of a loss of democratic control.
These and other contradictions which had attracted very little attention in the past have been the central concerns both of PRIF's basic research work and of the institute's policy advisory activities in the 2000. For more information, see this central conceptual text.
„[T]he ‘Antinomies of Democratic Peace‘ project, an initiative undertaken by the Peace Research Institute Frankfurt (PRIF) and led by Harald Müller […], represents the most sustained contribution to the development of a critical research programme through exploring the tensions, contradictions and ‘dark sides’ of the democratic peace. The PRIF project has resulted in a series of publications, including two important edited books: Democratic Wars: Looking at the Dark Side of Democratic Peace (Geis et al. 2006) and The Militant Face of Democracy: Liberal Forces for Good (Geis et al. 2013), which explore the relationship between democracy and war ‘as the flipside of democratic peace’.”
Source: Christopher Hobson, The Rise of Democracy. Revolution, War and Transformations in International Politics since 1776, Edinburgh: Edinburg University Press, pp. 24-25.