In 2005, Joseph Colomer looked at 219 elections in 87 countries from 1874 on and found that the trend over time was clearly towards proportional representation. He writes that today,
“more than four-fifths of today’s democracies in countries with more than one million inhabitants use electoral systems with proportional representation rules (80.5 percent), while less than one fifth use majoritarian rule systems (19.5 percent).” 1
Over 80% of OECD countries use proportional systems.
According to the Ace Electoral Knowledge Network (Table 1), of 31 countries which have changed their electoral systems in the past 20 years, 27 increased the proportionality in their electoral system and only one moved in the opposite direction.
Colomer notes that the number of parties in a country is not something brought about by the introduction of PR. The causality runs the other way, with evolution to PR following the emergence of a diverse, multi-party system. The higher the “effective number of parties” (ENP) a country has – a term defined by Lijphart which classifies the number of parties in a legislature by their effective power – the higher the probability that country will switch to proportional representation. Colomer notes:
“The average ENP in the last election held by majoritarian rules before the change of the electoral system is 3.9.” and that the likelihood that a country will switch to a proportional system rises to 61% when a country reaches 4 effective parties.”
Canada’s last Parliament had 3.43 “effective parties”, however, we have been close to 4 effective parties since 1997.
Alan Renwick and Jean-Benoit Pilet note that countries already using proportional representation are moving towards candidate-centered systems – “personalization.” This refers to designs which allow voters to vote for individuals instead of only parties.2
1 Colomer, Joseph (2005) It’s Parties That Choose Electoral Systems (or, Duverger’s Laws Upside Down), Political Studies: VOL 53, pp. 1–21.
2 Renwick Alan and Pilet Jean-Benoit (2016). Faces on the Ballot. The Personalization of Electoral Systems in Europe, Oxford: OUP.