Daniel C. Thomas is Professor of International Relations at the Institute of Political Science at Leiden University.

More information about Daniel Thomas

Short CV

Daniel C. Thomas is Professor of International Relations at the Institute of Political Science at Leiden University.

He served as head (‘scientific director’) of the Institute of Political Science in 2017-2020. He is co-founding director of the Leiden University Centre for International Relations (LUCIR), serves on the Steering Committee of the university’s Europe Hub and co-founded the university’s programme on Global Transformation and Governance Challenges (GTGC).

He was trained in political science at Brandeis University (BA) and Cornell University (MA, PhD). Before coming to Leiden, he held research and teaching positions at the European University Institute, Harvard University, Stanford University, University College Dublin, the University of Illinois at Chicago, the University of Pittsburgh, and Williams College.

He also worked on international human rights issues at the European Commission’s Directorate General for External Relations (precursor to the European External Action Service) in 2002-2003.

Research

His research focuses on international norms, international order, and EU decision-making regarding foreign policy and enlargement.

Among his current projects, he and Karolina Pomorska (Leiden University) are co-editing a Special Issue of Comparative European Politics (forthcoming 2025) on the protean power of Europe—how the EU responds to unforeseen external developments through policy innovation and institutional transformation. In addition, he and Matthew D. Stephen (Helmut Schmidt University) are leading a multi-author project on how shared understandings of the aims or purpose of governance shape international cooperation and the evolution of international order.

His latest book—The Limits of Europe: Membership Norms and the Contestation of Regional Integration (Oxford)—uses normative genealogy, statistical regression, qualitative comparative analysis, and process-tracing methods to demonstrate how evolving normative definitions of Europe as a political community shaped EU decision-making on enlargement from the late 1950s to the present, with a detailed focus on policies toward Greece, Spain, Turkey and Ukraine.

Based on his experience in Brussels, his book Making EU Foreign Policy: National Preferences, European Norms and Common Policies (Palgrave) explains how and under what conditions shared substantive and procedural commitments enable EU member states to adopt common policies despite divergent preferences.

His first monograph—The Helsinki Effect: International Norms, Human Rights and the Demise of Communism (Princeton)—demonstrated how civil society groups in Eastern Europe and the Soviet Union built coalitions, mobilized foreign support and promoted political change by leveraging international norms in their confrontations with Communist regimes. It also appeared in Czech translation as Helsinský efekt: Mezinárodní zásady, lidská práva, a zánik komunismu (Academia).

He has also published Negotiation Theory and the EU: The State of the Art (Routledge), two editions of World Security (St. Martin’s), and Peace and World Order Studies (Westview), plus journal articles and book chapters.

Teaching

He teaches courses on theories of international relations and the dynamics of international organisation, and supervises research students in these and related fields.

PhD supervision

Daniel Thomas is available to supervise PhD students and invites PhD research proposals in the areas of:

• international relations
• international organisation
• European integration
• politics of human rights

See for more information on PhD positions:

› Institute of Political Science: PhD

Publications

Activities