In decent voting systems, you vote in party C.

I don't think there's any voting system that genuinely gives you three choices to lead government at every election. Even in proportional systems, you might be able to select someone who more closely represents your interests and can advocate them in parliament, but the government is probably going to be led by one of the same two parties over time. If party A and party B are both ideologically inclined to fuck up rail, getting party C elected as a junior partner probably won't change that.

And if you're just hoping to replace party A entirely with party C, FPTP is one of the better systems as long as you're not in a country where election laws are set up to ensure that the Democrats and the Republicans are going to win almost every election. But that's a question of candidacy laws and incumbent rights; changing the voting system in the US won't suddenly cause other parties to get elected.

Anyway, the fact that party A fucked it up and party B is fucking it up doesn't mean party A lacks incentives to improve it tomorrow. Perhaps they fucked it up because their leader was incompetent, and now that there's been a change in leadership they will be motivated to improve.

> but the government is probably going to be led by one of the same two parties over time.

Finland has generally had 3 major parties ducking it out usually around 15-25% for each. 1995 was last time single party got over 30% of seats. Depends a bit on time which exact ones they were.

English wikipedia doesn't have the historic list, but Finnish does https://fi.wikipedia.org/wiki/Eduskunta#Kansanedustajat_puol... Divide by 2 to get the % (there are 200 members)

Population size is a big problem. The more you scale up a democratic system, the more it becomes difficult to bootstrap and maintain a coherent political movement that can have a realistic chance to win an election, in what is probably a logarithmic scale. So the bigger the country, the more entrenched the options will be, which eventually boils down to two sides when you approach certain thresholds (one for the current government, and one against it).

France has had a million parties. Romania, too. Italy, same. If there's a will, there's a way. Most of the time there's no will.

If there was only one issue to vote on. However party C will have some other negative that I hate that party A is best on and party B is okay.

The only system that doesn't have voting negatives to me is one with a population of less than 10 where I'm sole dictator. Any population more than that and someone will get mad at me and kill me. Republics with some form of voting are the best option I know of for large populations of people who aren't "mind numbed robots" with no ideas of their own, and there is room to tweak the voting system. However they are still terrible for getting good results.