Does center equal middle? Towards a conceptual delineation, with application to west European party systems

The concept of center parties has been stretched so far that it can no longer serve as a defining characteristic. The multiplication of center parties, and the migration of other parties towards the center, has left the academic literature without the proper methodological tools to identify, define and classify an increasing number of the parties in most party systems today. I propose a delineation of the concept, differentiating between ideological center parties and spatial middle parties. Related terms such as center label parties, median parties and pivotal parties are addressed in presenting a new conceptualization and classification of the center and center parties. Examples of each type are subsequently presented and elaborated in the context of the Italian and Dutch party systems. The new concepts are then analyzed and discussed within a comparative perspective of West European parties and party systems.