[noizejoy]

> single ballot, winner take all systems inevitably tend toward a two party equilibrium.

I'm not convinced it's quite that simple.

For example, Canada also has a first-past-the-post electoral system - yet political parties here have come and gone. And continue to do so.

[tialaramex]

Parties come and go, but there will be two major parties. In fact under such as system if you're in one of those two big parties and you see a third party rising you need to figure out whether it's you or the other guys getting replaced, 'cos it won't stay a three party system for long.

For example in the UK, the Tories ("Conservative and Unionist Party") and Labour are currently the biggest parties, but a hundred years ago this was a novel situation, Labour were seen as a third party, while the Liberal party (which was eventually absorbed into what is today "Liberal Democrats") had seen success over decades and were often in government prior to that point.

[saalweachter]

A lot of it depends on whether your governing coalitions are formed before or after the election.

The US parties are just coalitions of disparate interests joining together until they (maybe) represent enough people to have a majority and be able to enact their collective interests.

[emodendroket]

I mean we're on the sixth "party system" in the US too, if that's your standard (it's a new "party system" when there's a significant realignment of which interests find themselves in which parties, either by a reshuffle among existing parties, or by new parties rising and old ones falling). Have you heard much about the Federalists or Whigs lately?

[AmericanChopper]

The voting demographics change frequently as well. California has voted to elect more republican presidents than it has democrat ones. It’s voted democrat in the previous 8 elections. In the 10 elections prior to that, 9 times it voted for republican candidates. Texas has also voted for more democrat presidential candidates than republican ones. People who think the US democracy is a rigid and highly predictable system simply have a recency bias.