Introduction: The Role of Theory in Research on Common Security and Defence Policy

Research on European Security and Defence Policy (ESDP), which has become Common Security and Defence Policy (CSDP)1 with the entry into force of the Lisbon Treaty, is said to be notoriously undertheorised. The first wave of literature on the subject resembles diplomatic history, being based on journalistic accounts of key events. It tends to cite official documents about institutional development, together with anecdotal, politically loaded or otherwise speculative evidence about the motivational factors (Forberg 2006). Subsequent works either deliberately avoid over-theoretical explanations (Howorth 2007), apply one distinct theoretical lens — as is the case of research on the socialisation of Brusselsbased elites — or are concerned with policy description, where theory allegedly obscures the understanding of political reality. The present volume seeks to address this charge of undertheorisation. It brings together scholars in the field who map their respective theoretical apparatuses, reflect on their purchase and illustrate how they have informed their empirical explorations. Diversity of theoretical assumptions has pervaded the literature on the subject from the outset. The available work on CSDP builds its explanations on distinct — if implicit — premises, which inform its prescriptions for how policy should develop. In this respect, it illustrates the notion that all theories intertwine empirical and normative ingredients (Reus-Smit and Snidal 2009), sometimes in denial, sometimes subconsciously, sometimes overtly.