Defractionalisation in Different Electoral Systems

Electoral systems face two competing aims: firstly to ensure that the transmission of citizens’ votes into parliamentary seats is proportional and secondly, that the legislative body has a stable majority to back up a government.

As a result, there tend to be major differences between national electoral systems in terms of their respective history and depending on whether proportionality or the capacity to govern is considered as more important. While the aim of proportionality demands that the legislative body should be as fractionalised as the electorate body, the aim of building enough capacity to govern demands at least some degree of defractionalisation.

In this article a measure used to quantify the degree of defractionalisation is discussed and applied to legislative bodies in different European countries.