[EM] 12/13/02 - Giving `crutches to weak candidates':

[Adam Tarr]

I must admit I'm not the least bit surprised that Donald Davison has not 
responded to my message from 12/18.  This is standard debating style for 
Donald -- post an inflammatory criticism of Condorcet or Approval, ignore 
the reasoned responses, rinse, repeat.  Would it be too much to ask him to 
defend IRV from criticism, this time?

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:
>
>>... why are
>>you supporting Condorcet and/or Approval Voting?  For, this is what these
>>two method do, they give `crutches to weak candidates'.
>
>Do you mean weak candidates like "Centrist", below?
>
>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?
>
>>Non-monotonicity is a bad joke, it does not exist, it has never
>>happened in a real election,
>
>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?
>
>>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.
>
>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.
>
>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.
>
>>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.
>
>Approval, granted.  It's easy to get bad results in approval if the voters 
>vote very stupidly.
>
>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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