Comment by cyphar

The UK has two major parties. The fact that the LibDems were in a coalition government once due to a hung parliament (and the last hung parliament was in 1974) isn't really evidence that the UK has more than two major parties. A major party actually has a chance to have a plurality. I also hasten to point out that the LibDems currently have 11 seats (the SNP has four times as many).

Many European countries with non-FPTP systems have coalition governments all the time and there really are several viable major parties.

To be fair, preferential voting isn't a panacea (and arguably should be paired with multiple-representative electorates). Here in Australia we have instant run-off voting and there are still two major parties with even less crossbenchers than the UK parliament -- though our Senate does have a fair few independent and third-party candidates, likely because Senate seats aren't winner-takes-all (like electorate seats are for the House of Representatives). I think voter education is also partially to blame -- many Australians seem to not be aware of how preferential voting works.