[EM] Autodeterrence introduction & definitions

[Kristofer Munsterhjelm]

On 2024-01-12 22:16, Bob Richard [lists] wrote:

> (1) I'm not sure that C is actually the Condorcet winner here. I think 
> we have A tied with B 49-49, A tied with C 49-49 and B tied with C 
> 49-49. I think a more straightforward example of Toby's point is
> 
> 48: A>>>>C>B
> 48: B>>>>C>A
>   3: C>A>B
>   1: C>B>A
> 
> C beats B 52-48. C beats A 52-48. So C is the Condorcet winner. The IRV 
> winner is A.
> 
> (2) To most defenders of Condorcet, this is a strength, not a weakness. 
> C _should_ win in this example because (to oversimplify) the point of 
> elections is to elect the median candidate.
> 
> I am not a defender of Condorcet primarily because of exactly this 
> situation. I believe that, in Toby's original example, the result should 
> be a tie. In my example, where the 4 C voters have second and third 
> choices,, they should get to break the tie in favor of A.
> 
> My point is not to argue that A should win. My point is that who should 
> win in this situations is a value judgment. My view is as much a value 
> judgment as the contrary view that C should win. No amount of social 
> choice theory or analysis of criteria compliance can dictate that judgment.

I suspect that, if all you have are ordinal ballots, then you have to 
guess wrong *somewhere*. A Condorcet method will guess wrong where it 
sees something like your example above. But if you design the method to 
put a greater weight on first preferences, then the area where it 
guesses wrong shifts over to natural Condorcet winners and you get 
center squeeze.

That's not to say that center squeeze methods are on the optimal 
boundary - after all, some methods are just worse than others. But for 
methods on it, there's a value judgement about what kind of errors 
matter more than others.

Though looking at it from another angle, voting methods that aren't 
perfect will require some kind of value judgement. Even if it's just 
"multiple parties are good, and having these flaws will lead to extreme 
Duvergerian laws keeping third parties from appearing".

(If I recall correctly, there was a list member long ago who advocated 
that a voting method should not allow multiple parties, and that third 
party influence should be limited only to what major party they might 
make stronger. But I'm not sure if he was fitting his methods to his 
value judgements or vice versa.)

-km