Introduction

The Duvergerian theories have largely been the frame of reference upon which parties' and voters' strategic decisions have been explained. This chapter identifies the determinants of party entry decisions in Duvergerian contexts and explains how the overlap of electoral arenas can undermine this logic. It deals with the benefits and the costs of competing and summarises how party-entry decisions are expected to be taken under the Duvergerian assumptions. The Duvergerian theories are built upon the mechanical and the psychological effects of electoral laws. The chapter argues that the assumption of the independence of electoral arenas that the literature has purported up to now is false, thus enabling the emergence of contamination effects between different arenas. The contamination effects are supposed to deactivate the functioning of the Duvergerian gravity. Under the Duvergerian assumptions, political parties are expected to run for elections when they expect to achieve representation.