Choice voting is the method of proportional voting used to elect the parliament in the Republic of Ireland and to elect local assemblies in Northern Ireland (see Proportional Voting in Northern Ireland. Choice voting (also called "single transferable vote" and "preference voting") is a candidate-based system in which voters rank candidates in order of choice: 1, 2, 3 and so on. Voters in Ireland tend to vote primarily along party lines, and the result of the system is that parties win seats in close proportion to their vote in particular constituencies. Most districts have representatives from many parties, maximizing representation for the vast majority of voters.
Choice voting is quite popular in Ireland. Earlier in the century it was upheld in two national ballot measures, and the report of a recent constitutional commission commented on its popularity. The 1997 parliamentary elections were instructive -- particularly in how the system eases polarization. There are 41 constituencies in Ireland of between three and five representatives. Using choice voting in such constituencies creates "winning thresholds" (the percentages of votes a candidates needs to win a seat) of between 17% (when there are five seats) and 25% (when there are three seats).
All of these constituencies have representatives from at least two parties. Smaller parties also won a fair number of seats, but proportional voting hasn't meant the "breakdown" of a two-party system: rather, it has created a competitive two-party system, both in the sense that every constituency has healthy competition and that the major parties have enough competition from smaller parties to ensure their responsiveness to their core supporters.
Ireland certainly has done well economically in the last two decades; its economy has been the fastest-growing in Europe, to the point that its gross domestic product is higher than that of the United Kingdom on a per capita basis. The voters have kept legislators working hard, however. Incumbents face a steep uphill battle on election day.
The combination of every constituency having representatives from more than one party and both parties having a recent history of governing the country has certainly created a less polarized political environment than in the United States Congress. In the United States, in contrast to Ireland, it is very rare for a party to lose control of Congress (it has happened once in 44 years), while most districts are one-party fiefdoms.
Learning from the Irish
Ireland has been having a remarkable run, with its economy the fastest growing in Europe for the last few years. It has achieved a higher per capita gross domestic product than the United Kingdom. But there haven't been any Thatcher-esque assaults on the safety net. And while Ireland is an overwhelmingly Catholic country that frowns on divorce and abortion, women steadily have increased their power to control their lives.
Electorally, the United States may have something to learn from our Anglo-Irish cousins. Ireland has a combination of instant runoff voting for executive elections and proportional representation for legislative elections. In 1990, Mary Robinson became Ireland's first woman president when the instant runoff voting system vaulted her to victory in the runoff round. She was succeeded by Mary McAleese in 1997, when McAleese won on the second round of counting among a field where the top four candidates were women.
Elections for the more powerful national parliament are also lively. Even as the economy has boomed, voters have kept legislators honest with incumbent governments frequently losing subsequent elections, although coalitions between elections have been reasonably strong and steady. Six parties from across the political spectrum have consistently won seats in the 1990s, and each party in that decade served as part of one governing coalition or another. Every Irish resident has at least one local representative from both of the major party alliances, meaning that no part of the country is left behind when political tides change. And the choice voting ballot method used in presidential and legislative elections ensures that voters never accept a lesser of two evils; they can fearlessly vote for their favorite candidates.