RCV actually literally has the exact same problem you're describing with voting strategically, it's just subtler and harder to understand. The problem is, if you rank A > B > C, then your subsequent preferences after A only matter if A gets eliminated. If A comes in second place, then your "B > C" preference has no impact, and C may be elected whereas if you "dishonestly" voted for B first you might have allowed B to win.
The point of ranking is not to have your vote redistributed many times, but rather for your #1 preference to go to your preferred candidate.
If your preferred candidate does not win, your vote gets a second chance (or more!) to get counted.
In the case your describing here, the only way that C wins, is that he gets more votes than A or B.
But that's not always the case; this is exactly the point I'm trying to make. The whole problem is that your vote only gets a second chance to be counted if your preferred candidate gets eliminated. If your preferred candidate loses because somebody else wins before your preferred candidate gets eliminated, then none of your later rankings affect the outcome whatsoever. This is why you can't actually vote honestly in IRV if you want your vote to count.
Let me try to illustrate this with an example:
Let’s imagine the US switched to RCV before the 2020 election, and Mitt Romney decides to run as an independent. Now let’s look at, say, West Virgina, which is a pretty red state, and went about 70% Trump 30% Biden in the 2020 election in real life
WV Democrats are still going to vote for Biden, and they’d probably prefer Romney over Trump, so let’s say they all vote in that order, but imagine roughly a third of Republican voters in West Virgina like Romney better than Trump, so we end up with this:
45% vote Trump, Romney, Biden; 25% vote Romney, Trump, Biden; 30% vote Biden, Romney, Trump
Romney gets eliminated first, his voters fall back to Trump, and Trump wins. The Democrats all wanted Romney over Trump, but Biden was never eliminated, so their second choice of Romney had no bearing on the outcome. But, what if they’d strategically voted for the “lesser of two evils”?
now we have: 45% vote Trump, Romney, Biden; 25% vote Romney, Trump, Biden; 30% vote Romney, Biden, Trump
Now Romney is a clear winner, he has the majority of first choice votes, so nobody’s second or third choice even matters. So basically in this example, Biden was a spoiler candidate for Romney, and all those Democrats are going to be super disillusioned when they realize that the “it fixes the spoiler effect" and "you can vote honestly” lines are both wrong, and they could’ve had a better outcome if they’d voted strategically, just like in the old system.
Take the German system: there are district level elections, so that there is one person elected in each electoral district. These get half the nominal seats. Then the other half of parliament is filled up with candidates to match the proportional vote. The fill up is a bit complicated, especially if a party has a lot more directly elected folks than proportionally mandated, which leads to growth of parliament and discussions how that growth can be avoided. (Larger districts and only 1/3 directly elected or not every directly elected candidate really making it or not holding up the exact proportionality or whatever) But it combines the factors mostly fine and avoids many of the problems of the pure systems.
If you elect, oh, 5 people in each district then your proportionality is still granular to about 17% of the vote in the district (for single member districts it's granular to about 50%, of course). And your districts are 5x as large as single member districts are for the same number of representatives. What it does give you though is better electability for local independents.
With mixed-member proportional you can easily get down to couple-percent granularity while maintaining medium-size districts (typically twice as large as single-member).
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.
Approval doesn't have these problems; it's a clear win.
I'd argue that the algorithm is far more complex. It is `while no winner: pop(min(candidates)); reallocate(min(candidates))`. This while loop is quite a problem. Cardinal systems (except STAR) are `argmax(sum(candidates))`, which is actually identical to Plurality. The difference is that Plurality requires a one-hot vector. This algorithm is trivially parallelizable too. STAR doesn't require a while loop but is more complex because it does have 2 phases (which RCV is almost always going to be more than 2 phases given that while loop).
The trivializes of cardinal systems tallying algorithm makes statistical audits also trivial. I just can't imagine the mess we'd be in if what happened in Arizona happened with an ordinal method like RCV. It would be much easier to create a narrative of fraud.
I agree that proportional representation is a huge deal, but I suspect we can do better than STV by changing what the election results mean. Currently in every system I know of we treat it as a binary choice; a candidate is either a member of the set of candidates who won, or they aren't.
A different way to do it is to allow every candidate who receives some minimum threshold level of support to be elected, but when voting on issues each elected person's influence is weighted by the level of support they received in the election.
This sort of system is compatible with FTPT, RCV, or approval-voting style ballots, but the differences matter less as long as you can say of the vast majority of voters (assuming an omniscient view -- privacy of votes would obscure the actual data) that that voter clearly has a representative in congress, and that voter delegated the same amount of influence to that representative as any other voter. (People who only voted for fringe candidates that don't meet the minimum threshold lose out, but that would probably be rare among people who actually pay attention to politics and aren't casting a protest vote.)
If this were enacted for the U.S. House of Representatives for example, the likely outcome would be that each state would have at least one Republican and at least one Democrat who would wield different amounts of power depending on how popular Republicans and Democrats are in that state. You'd also have Libertarians and Greens and Independents and whatever else. A state might have two representatives after one election and ten after another, and it wouldn't be a problem because influence is the same.
STAR and Approval both have their own tactical voting problems. If you really like A, are meh about B, and dislike C, it’s clear you should rate A high / give A your approval and rate C low / do not give C your approval. But what about B? It has nothing to do with what you actually think about them, it has to do with what you think their odds of beating C and A are. You want B to do well enough to beat C, but not well enough to beat A. This adds too much distortion to people wanting to express their sincere preferences, which they can easily do in RCV: A > B > C
And, more importantly, RCV is a stepping stone to multi-member district STV proportional voting (plug for https://www.fixourhouse.org/), which is the golden goose; way more important to implement proportional representation than squabble about STAR vs RCV, and RCV gets us closer to proportional representation.