Americans for some reason have fixated on FPTP as the cause of the two-party system and hope RCV/IRV will extract them from it.
The basis of a two-party system is actually single-member electorates. Because each seat can only have one representative and the economics of campaigning and organising make it hard for a third party to make appreciable inroads.
Australia's Parliament demonstrates the differences: the House of Representatives is composed of single-member electorates and is dominated by the two major political organisations (and this is for the good, as the government is formed in the House and a two-party system almost guarantees that a government can be formed and sustained easily after each election). The Senate, by contrast, is composed of multi-member electorates, one for each state, elected on a proportional basis. While the major parties typically have the largest share between them, the nature of a proportional multi-member electorate is that it creates more room for minor parties to obtain one or two seats.
Thanks for the thoughtful response. I agree that there are other structural challenges in the way of making additional parties really viable. My theory is that changing from FPTP would sort of break the ice and allow other parties to gain momentum, normalize the idea of other parties not being totally fringe, and maybe pave the way for some other enabling changes once it’s no longer strategically a terrible idea to vote for the candidates you prefer but almost certainly won’t win. It’s not the only change that would help, to be sure.
The basis of a two-party system is actually single-member electorates. Because each seat can only have one representative and the economics of campaigning and organising make it hard for a third party to make appreciable inroads.
Australia's Parliament demonstrates the differences: the House of Representatives is composed of single-member electorates and is dominated by the two major political organisations (and this is for the good, as the government is formed in the House and a two-party system almost guarantees that a government can be formed and sustained easily after each election). The Senate, by contrast, is composed of multi-member electorates, one for each state, elected on a proportional basis. While the major parties typically have the largest share between them, the nature of a proportional multi-member electorate is that it creates more room for minor parties to obtain one or two seats.