Electoral System Design

The Major Electoral Families

Electoral systems fall into three broad families. Plurality/majoritarian systems award seats to whoever gets the most votes in a district. The UK's first-past-the-post (FPTP) system is the simplest version: whoever gets the most votes wins, even if that is only 30% in a multi-candidate race. France uses a two-round system: if no candidate wins a majority in the first round, the top two face a runoff.

Proportional representation (PR) systems allocate seats in proportion to vote share. If a party wins 30% of the vote, it gets roughly 30% of the seats. The Netherlands, Sweden, and South Africa use full PR. Mixed systems combine both: Germany's Mixed-Member Proportional (MMP) system gives each voter two votes — one for a district candidate (FPTP) and one for a party list (PR). Japan and New Zealand use similar mixed systems.

Duverger's Law and Party Systems

French political scientist Maurice Duverger observed that electoral systems shape party systems with remarkable predictability. First-past-the-post tends to produce two dominant parties (Duverger's Law), because voters do not want to 'waste' their vote on a third party that cannot win. Proportional representation tends to produce multi-party systems (Duverger's Hypothesis), because even small parties can win seats.

The US and UK (both FPTP) have two dominant parties. Germany, Sweden, and the Netherlands (all PR or mixed) have four to seven significant parties. This is not coincidence — it is a direct consequence of institutional design. Constitutional framers choosing an electoral system are, whether they realize it or not, also choosing a party system — and by extension, the kind of government (single-party majority vs. coalition) their country will have.

District Design and Gerrymandering

In district-based systems, who draws the district boundaries determines who wins. Gerrymandering — drawing districts to advantage a particular party — is as old as the American republic (the term dates to 1812). Modern gerrymandering uses sophisticated software to produce districts that look bizarre but are mathematically optimized for partisan advantage.

The solution varies by country. The UK uses an independent Boundary Commission. Australia uses the Australian Electoral Commission. Canada uses independent commissions appointed by the judiciary. In the US, most state legislatures draw their own districts — a textbook case of the fox guarding the henhouse. Some states (California, Arizona, Michigan) have adopted independent redistricting commissions through ballot initiatives, but the practice remains the exception rather than the rule.

Electoral System Families

As Duverger observed, choosing an electoral system is also, in effect, choosing a party system, and by extension whether governments will be single-party majorities or coalitions.