So go ahead Don, read below, or read the original, and respond. Explain why the centrist candidate below should lose (although he shouldn't). Explain why the example below is unrealistic (although it isn't). Explain why IRV's monotonicity violations are less of a concern that Condorcet's cyclical ties (although they aren't). Even better, provide an example that is realistic in your estimation, where Condorcet elects a bad candidate. (I bet you can't.)
Good Luck, Adam
On 12/18/2002 I wrote:
Don Davison wrote:Do you mean weak candidates like "Centrist", below?... why are you supporting Condorcet and/or Approval Voting? For, this is what these two method do, they give `crutches to weak candidates'.
10% FarRight>Right>Centrist>Left>FarLeft
10% Right>FarRight>Centrist>Left>FarLeft
15% Right>Centrist>FarRight>Left>FarLeft
16% Centrist>Right>Left>FarRight>FarLeft
15% Centrist>Left>Right>FarLeft>FarRight
13% Left>Centrist>FarLeft>Right>FarRight
11% Left>FarLeft>Centrist>Right>FarRight
10% FarLeft>Left>Centrist>Right>FarRight
Note that this is an easy, realistic example... I just put five candidates on a standard political spectrum.
Let's look at who has the most first-place support:
31% Centrist
25% Right
24% Left
10% FarLeft
10% FarRight
Or who has the most second place support:
28% Centrist
26% Right
25% Left
11% FarLeft
10% FarRight
In addition to having the most first AND second place support, Centrist is the only candidate that is never ranked lower than third on any ballot. And yet, as you surely realize, Centrist loses in IRV. Right will beat Left 51%-49% in the final runoff, even though Centrist would beat Left or Right by around thirty percentage points -- absolute landslides.
How could anyone call Centrist a "weak candidate" with a straight face? Weaker than who?
This is because no real election has ever had three strong parties. IRV keeps any third party from threatening the other two. History backs me up on this. Is that a positive feature in your mind?Non-monotonicity is a bad joke, it does not exist, it has never happened in a real election,
That's a lie. Steph responded. He correctly pointed out that due to the extremely strong support for a few candidates, there was no monotonicity violation there. I'd draw an analogy to Condorcet voting - you're not going to find a cycle every time. Monotonicity violations in IRV elections would be a bit more common than cyclic ties in Condorcet elections. Which is to say that neither would happen in elections with two strong factions.A few months ago I posted some real ballots to this list and requested anyone to use the ballots and prove that Irving or STV can be non-monotonicity in the real world. No one responded.
It's worth noting that those were STV ballots, and it's not clear that candidates and voters would have acted the same way if it had been a single-winner election. It's also worth noting that I could have easily drawn out a subset of the votes and found a Monotonicity violation lurking, if those had been the only votes. But I don't think that proves much, except that IRV can fail monotonicity (and we already knew that).
I don't think of monotonicity as the great demon of IRV. I think of it more as a red flag. If a method fails Monotonicity, then it's a sign that it can be manipulated or can produce unfair results in other cases. Which is true for IRV.
Approval, granted. It's easy to get bad results in approval if the voters vote very stupidly.Pity votes will have little influence in an Irving election, but the bad effects of `pity votes' can easily happen in the two methods, Condorcet and Approval.
But Condorcet? Show me the example, Don. Dream up something. Show me my second-place votes beating my first place votes. Oh, you can do it, but it's not easy at all. It takes some very strange breakdowns in voting. When you finish making such an example, will you be able to say, "that example is more realistic than the monotonicity violations"? Or will you be able to say, "that's a less democratic result than the monotonicity violations"? I'd guess no, and no.
Come up with an example, Don. Or are "charlatans" the only ones who create examples?
-Adam
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