You don't think normal people can understand: "Rate this candidate from 0 to 5 stars?" If so, we really need to rethink a lot of how we ask for people's opinions, because this is probably the most common way.
In RCV it's safe to put your first choice first if either they're an overwhelming favorite to win, or they're so weak they're sure to get eliminated right away. If it's a close three-way election, you might cause your favorite candidate to lose by ranking them first. It's hard to develop any kind of intuition around how your vote will impact the race in these situations -- I think in the long run voters tend to learn that voting for third parties isn't safe, so two parties continue to dominate.
Could you explain that? I can't think of a situation where putting the candidate I want to win as #1 would cause them to lose. Ranking other close candidates as #2/#3 could cause my #1 to lose, but I don't think voting for someone as #1 alone would possibly harm them.
(strategies exist for ALL voting systems. But not all strategies are equally as bad)
That's an important point. Also, just because a strategy exists in theory, doesn't mean that in practice any voter can confidently find that strategy (since they lack perfect information about how all the other voters intend to vote).
A is left, B is center, C is right leaning.
Polling shows that voters are leaning:
- 15% BAC
- 15% BCA
- 25% ABC
- 45% CBA
If everyone voted as they desired, then the instant runoff would be between B and C, with B winning with 55% of votes.
If a subset of C voters instead strategically vote ACB (6%), this would change the runoff to be between A & C, with C winning 60%.
These are post facto strategies though. You can only implement that strategy if you can guarantee all of that information. Which you can only do after the election.
The first problem is that polling is an estimate. If you are wrong by a couple of percentage points, the strategy fails. If the results come back 16 (BAC), 16 (BCA), 23 (ABC), 39 (CBA), 6 (ACB), B now has 32 first votes and A only has 29.
Next is getting the right number of people to comply. You could easily just mess it up and have either not enough or too many people cast the strategic ballot. If only 4% or less vote ACB, the plan doesn't work. If 11% or more vote ACB, A wins.
In the end, strategic voting is a bit like voter fraud, talked about way more than is actually done. And implied to be a much bigger problem than it ever could be.
Because the relevant fact here isn't that some CBA voters put A at the front (ACB). It's that they moved B from 2nd to 3rd. So of course, that lessens support for B, so B no longer wins.
People seem to present this as a flaw, when it's reflecting actual changes in voting. And this is basically impossible to do so strategically, because nobody has this level of accurate detail prior to the election.
The empiricval evidence in countries with long term ranked voting (Australia, say) is that bicameral party systems (only Democrats or Republicans have any realistic chance) wither and die, and smaller blocs have a better chance of survival and impact | influence in the House and Senate ..
Two parties "dominate" in Australia (or rather three parties, which are effectively two - the Nat-Liberals being an Rural-Urban conservative coalition of long standing) but nowhere near the degree to which two parties dominate in the USofA; more importantly minority opinions have gravitas and can sway the major vote - none of this bipolar US Dem-Rep deadlock.
That's a flawed characterization that keeps getting repeated.
As I explain in another comment below, in theory you could get your favorite candidate to win by further downranking the candidate who would otherwise win. One way of accomplishing that is to move other candidates up higher above your actual preferred candidate.
But in reality, there's no way to know what the exact precise vote breakdowns will be, so voting strategically (lying about your preferences) is impossible in a practical sense. There's no intuition to develop -- just vote your preferences.
To claim it is impossible in practice is to deny history.
[0] https://electowiki.org/wiki/Favorite_betrayal_criterion
And if it is not as simple as "Bob got the most votes, Bob won" it's going to get harder and harder to explain exactly what is going on, which is going to get people annoyed and angry.
As long as the result is the same as would have come from first past the post, nobody will care.
I'm not understanding your point. In cardinal systems a non rating is equivalent to a rating of zero. Just like in ordinal systems a non ranking is equivalent to ranking last place.
> And if it is not as simple as "Bob got the most votes, Bob won" it's going to get harder and harder to explain exactly what is going on
This makes it seem like you're in favor of cardinal methods actually. Tallying their votes is pretty trivial. You sum the scores of all candidates and then argmax the totals. I don't think people have a hard time understanding this. It is essentially the same as what happens with FPTP! I mean this is objectively a simpler algorithm than those used by even the simplest ordinal methods.