Your vote can be overridden no matter what. There’s nothing saving you from that. Party platforms in any kind of system aren’t very good promises on what will happen.
I’m not sure if it was just a poor choice of words but there’s no necessity to compromise to form a coalition. A party can decide not to participate or come to the conclusion that they aren’t able to form an effective coalition (if the biggest party).
Opposition is not united in this case and can do nothing
And what, you think in two party system the opposition party can just take down the government from minority position? Of course the opposition can rally against the government and hope their lines break. Which is something that can be more likely when it’s a coalition. But it being a single or multi party doesn’t matter. If government lines hold, there’s nothing to be done other than rallying against them and waiting for the next elections.
Most likely you have like 20% and the rest are in-between to be opposed or not opposed
In my experience that is not at all the case, rather parties supporting the standing government outside of it is a rarity. Such party will most likely suffer from unpopular decisions of the government and not benefit from the possibility of being in opposition. It’s rarely a smart position to be in.
Not to mention in multi-party system, it’s not just sitting government vs opposition that are fighting, but the parties within the coalition and parties in the opposition are competing. And after elections, some government parties might end up joining the new government formed by opposition parties and so on. The whole point is that it’s not just two opposing sides, this or that, but multitude of ideologies and platforms that are competing.
I agree with that in principle, but in practice, if one party starts taking 80% of votes, the other will adjust. On top of this, this situation is no different from 80% case in multi-party system so it is not what differentiate one from another.
I’m surprised. I thought the idea that two party system meant a strong opposition was one of your main points.