Does the Iron Curtain Still Exist? Trends and Sources of Electoral Volatility between Eastern and Western Europe (1990-2016)

The literature on party system change and electoral volatility in post-communist Europe tends to distinguish the countries of the region from those of the Western area. The basic assumption is that Central and Eastern European party systems have been characterized by a high degree of unpredictability, reflecting both supply and demand. Beyond the differences in terms of volatility (as an output), the literature lays emphasis on the specific “sources” of volatility. More specifically, while Western party systems’ volatility has regularly been associated with electoral shifts among existing parties, Eastern party systems’ volatility has been mainly connected with the continuous emergence of new political parties. This specific assumption raises numerous methodological and empirical doubts. On the methodological dimension, there is the absence of a comprehensive dataset of electoral volatility that brings together Eastern and Western European countries in line with consistent criteria for the calculation of the Pedersen index (e.g. cases of splits and mergers) and its internal components (regeneration, i.e., volatility caused by the entry of new parties and the demise of old ones; and alteration, i.e., volatility among existing parties). From an empirical point of view, the most recent electoral trends indicate that Western European party systems are facing unprecedented levels of volatility directly connected with the emergence of new political parties. Meanwhile, different post-communist countries have been demonstrating a progressive stabilization of their political offer. Considering the above, this contribution asks whether the historical division line between Eastern and Western party systems has been levelled in terms of trends of volatility and if the sources of the volatility also converge. In doing so, we proceed as follows. We present an original dataset of electoral volatility in Western and Eastern Europe since 1990 by taking into account the internal components of regeneration and alteration and we compare trends and across the 30 European party systems; then, we look at the determinants of volatility and its internal components, with the purpose of understanding which factors are able to explain the convergence in the two regions.