Arrow's Impossibility Theorem [video]

I live in Ontario, Canada, where there was a referendum on switching our voting system from first past the post. What ended up happening is that everyone starts to bicker over which specific voting system to switch to, proportional representation, run-off, this system, that system... so how do you vote for which alternative voting system to use?

While most people agree first past the post is a terrible system, not enough people are willing to unite to pick an alternative to replace it.

So approval voting probably is a fine system, but if you open the door to approval voting then you open the door to a host of other systems which act as spoilers and you're left with the status quo.

The score voting system satisfies IIA and can result in a situation where 50% of votes assign their highest score to Alice and lowest score to Bob, and 50% of voters assign their highest score to Bob and their second highest score to Alice. Alice would end up winning the election and there is no opportunity for the introduction of a new candidate who could act as a spoiler for Alice.

Arrow's impossibility theorem does not apply to score voting since the theorem only applies to voting systems where you rank your choices, it does not apply to systems where you rate your choices.

https://en.wikipedia.org/wiki/Score_voting