Proportional representation (PR) provides for the allocation of parliamentary seats to political parties in proportion to the votes they received in an election. As a principle of representation, the desired objective of PR is to reflect in parliament the existing political preferences and parties as accurately as possible. As a decision rule, in PR systems the share of votes candidates or parties receive determines whether they get a seat. In both aspects, PR is diametrically opposed to majority or plurality representation. Ever since the invention of PR as a decision rule during French Enlightenment and the mirror function of national assemblies during the French Revolution, majority/plurality and proportionality have built up the basic alternatives in debates on political representation. Regarding constitutional arrangements, their supposed impact ...