This paper examines the variables determining the emergence of international organisations (IOs) as actors in their own right. Scholars of International Relations have been studying this phenomenon under the heading of actorness and have identified many variables like autonomy, authority, cohesion, opportunity, presence or resources. The added value of the actorness conception is, however, rather marginal when compared to alternative approaches like principal-agent (PA) theory or social constructivism. The reason is that actorness is remarkably undertheorised and lacks an unambiguous definition to clarify connotation and denotation. This paper argues that current research on the alleged actorness of IOs and especially of the European Union underestimates the epistemological dimension of the concept. To date, research adopts actorness not so much as an analytical but rather as an empirical concept. By not being embedded in a comprehensive theoretical framework, actorness forgoes its potential to generate new and innovative insights established approaches fail to provide, e.g. when and in which policy area is actorness likely to emerge? When do third parties perceive and recognise IOs as actors? How do IOs’ sovereigns beneficially exploit the duality in actorness in international negotiations? To elaborate on the proposed argument, the paper proceeds in three steps: First, the literature is comprehensively evaluated and synthesised to examine the anatomy of actorness. Hereby key variables are identified and different explananda are disentangled. Secondly, actorness is delimited from other institutional approaches to outline research questions where actorness can be reasonably applied. Thirdly, the concept of actorness is (re-)defined to provide an unambiguous definition and an operationalisation that can be utilised in theory-driven research. The new definition is based on the idea of corporate action and enables scholars to distinguish IO action from state action, both conceptually and empirically.
