The existing empirical studies on the effects of enlargements of the European Union on the decision-making yield contradicting results. This indicates that further theoretical work to explain under which conditions the increasing group size either decreases or increases the speed of decision-making is needed. This gap is addressed in this paper by presenting an agent-based model, which depicts the dynamics of the decision-making through networks. It is the first model in the EU context that presents decision-making in 2 stages: (1) as an evolution of certain structure based on agents’ preferences and resources and (2) as an evolution of agents’ positions on a given issues based on the structure, their preferences and resources. The results of the simulations suggest that faster decision-making is possible only if the network evolves into a network with one strong central actor and that otherwise the increasing number of actors slows down the decision-making.
