[EM] DH3 pathology

[Dave Ketchum]

A PLAGUE on your "inflamed rhetoric"!

Looking at your starting example on the web page you refer to:
      37 C>A,B>D
      32 A>B,C>D
      31 B>A,C>D

With this, presumably fitting honest votes, C has a good chance of winning.

A and B voters would like to prevent C winning - possible since they have 
a solid prediction of honest votes and can vote any modified pattern they 
can agree on.

Since they had a bad night last night they do a plot that could win if 
they could do it without the C voters, also needing to sober up, 
retaliating by producing a result all will call a disaster.

Let them sober up and they could do better - just rank C as least liked in 
all their votes, and A or B will win.

DWK

On Sun, 27 Aug 2006 16:54:11 -0400 Warren Smith wrote:
>>RL Suter:
> 
> To make a dire warning about how "DH3 pathology" could
> cause "massive destruction" if any of the voting methods
> that are theoretically susceptible to it are used is little more
> than a rhetorical ploy...   What is most lacking in this and other discussions
> on this list about strategic voting is empirical data about
> how people vote in actual public elections in which different
> voting methods are used...  If the point is to make
> arguments that are logically compelling, such rhetoric
> is not merely unhelpful but extremely counterproductive.
> 
> --REPLY by WDS:
> 
> The reason I consider DH3 to be extremely serious and destructive,
> as opposed to some random election pathology example which is not
> so serious, is that is is extremely COMMON and when it happens it is
> very BAD.   It is the combination of the two
> 
> Why do I say COMMON?
>    Because all you need are 3 major rivals and at least one additional
>    "dark horse" candidate voters do not like and do not take seriously as
>    a threat to win.    This is very common.   Indeed, pretty much the
>    only occasions where this does not happen, are when you only have 2
>    major rivials, in which case, since plurality is the best system in
>    2-canddiate elections, the whole discussion about improving on plurality would
>    largely be moot.   Assuming we are having such a discussion, then
>    you have to regard DH3 as very common.
> 
> Why do I say BAD?
>    Because it causes the candidate unanimously agreed worst, to get elected.
>    That is as bad as it possibly can be.
> 
> I think these are objective criteria, not inflamed rhetoric. 
> Warren D Smith
> http://RangeVoting.org
-- 
  davek at clarityconnect.com    people.clarityconnect.com/webpages3/davek
  Dave Ketchum   108 Halstead Ave, Owego, NY  13827-1708   607-687-5026
            Do to no one what you would not want done to you.
                  If you want peace, work for justice.