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PhD defence

Hawks and Doves: Democratic Peace Theory Revisited

Tuesday 15 May 2018
Academy Building
Rapenburg 73
2311 GJ Leiden

Short summary

‘Democracies do not attack each other’. President Clinton voiced during the State of the Union in 1994 the belief in the so-called democratic peace, basically a not yet thoroughly explained empirical regularity. This regularity is considered to be an ‘iron law’ by many Western policymakers and political scientists, despite some flaws in the theory that aims to explain this particular peace.

This study investigates the micro-level assumption on which democratic peace theory rests. It aims to detect if there is a causal mechanism underlying the decision to attack another country when on the brink of war, and whether or not this mechanism differs between regime-types. It investigates whether or not regime-type, the nature of the conflict, the power used, and hawkish beliefs of decision-makers matter in this decision.

From a political psychological and comparative perspective, it tests simultaneously alternative theories of decision-making during conflict resolution. The core analytical instrument is a decision-making experiment, executed in the US, Russia, and China, which is subsequently supported by a large N study, and a case study.

The overall results show that although the democratic peace as an empirical regularity might still be valid, the theoretical arguments to explain why democracies do not fight with each other turn out to have been built on empirically unsupported foundations. This study argues that an actor-based approach towards decision-making processes within international relations offers important insights into the more structured-based theories of international relations. It thereby convincingly shows that the individual matters, also in international relations.


  • Leiden University Fund/van Steeden
  • International Peace Research Association Foundation (IPRAF)
  • Laboratory for Comparative Social Research (LCSR)


  • Prof. P. Kopecký


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PhD dissertations

PhD dissertations by Leiden PhD students are available digitally after the defence through the Leiden Repository, that offers free access to these PhD dissertations. Please note that in some cases a dissertation may be under embargo temporarily and access to its full-text version will only be granted later.

Press contact

Maarten Muns, Scientific Communications Adviser, Leiden University
+31 71 527 3282

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