[EM] Chris: Approval

Chris Benham chrisjbenham at optusnet.com.au
Mon Mar 19 10:21:25 PDT 2007

Michael Ossipoff wrote:

> Your definition of your criteria system sounds conversational and 
> inexact. Could you demonstrate why Approval and 0-10 CR fail 
> Condorcet's Criterion, in your system?
> Aside from that, why is it ok to speak of intent, but not preference?

Speaking of preference is an ok alternative, but we don't necessarily 
want to worry about what might be 'sincere preferences'
that are voluntarily not voted.

> Chris continues:
> [after naming a long list of criteria met by Approval]
>> But it fails Majority Favourite and Majority Loser
> Do you mean those criteria with your fictitious rankings? 


> I've never denied that rank methods can add advantages not available 
> in Approval. I've even said that I myself would prefer a good rank 
> method for our public elections, though I myself, as a voter, would be 
> content with Approval. It would be a nice luxury to rank the best 
> candidates, but I don't really care which one of the best candidates 
> wins.

That is your individual inclination, one which is very convenient for an 
Approval advocate.

> I'd said:
>>> Obviously majority rule is violated by an outcome that is contrary 
>>> to what a majority have voted that they want. For instance, if a 
>>> majority vote B over A, then we can assume that, if A or B wins, 
>>> they vote that it be B.
> Chris says:
>> That is reasonable, and granted for the sake of argument. That 
>> implies that you agree with Kevin Venzke that Minimal Defense(MD) 
>> must be met
> It does?? I don't agree with Keviln Venzke that Minimal Defense (MD) 
> must be met. 

 From Levin's page:

>       *Minimal Defense*. /(Due to Steve Eppley.)/
> /If more than half of the voters rank candidate A above candidate B, 
> and don't rank candidate B above anyone, then candidate B must be 
> elected with 0% probability./
> Steve Eppley has defined and discussed Minimal Defense here 
> <http://alumnus.caltech.edu/%7Eseppley/> and here 
> <http://alumnus.caltech.edu/%7Eseppley/Strategic%20Indifference.htm>. 
> Satisfaction of this criterion implies compliance with Mike Ossipoff's 
> /strong defensive strategy criterion/, although the reverse is not 
> necessarily true. That criterion can be found here 
> <http://www.barnsdle.demon.co.uk/vote/stfree.html>.

> It does?? I don't agree with Keviln Venzke that Minimal Defense (MD) 
> must be met. 

I'd be interested in seeing an example of  MD failure that you agree (or 
are content) with.

> Chris continues:
>> [Approval] is very vulnerable to disinformation campaigns
> That's a vague statement that could be said of many methods, including 
> some that Chris likes. 

My statement lacked details, but that doesn't make it "vague". I've 
elaborated this criticism of  Approval
a few times before.

Say in the lead-up to the election two candidates have announced that 
they will run, and accurate polling
of voters' voting intentions shows A52%, B48%. Say the media hate A, so 
others that hate A nominate
a third candidate C who is anathema to A's supporters (or at least some 
of them). Then those that hate A
set about giving C a high profile and publishing some fake polls that 
suggest that C has some chance to
win. This frightens some of the A supporters into approving B, causing A 
to win.

47: A
05: AB (disinformed timid A>B preferrers)
46: B
02: CB

Approval:  B53,   A52,  C2.

What  "methods that I like" do you have in mind as being comparably 
vulnerable to disinformation campaigns?

> Sincere preferences:
> 40: A
> 29: BC
> 31: CB
> The C voters vote C & B. The B voters vote only B. B wins by defection.
> Chris, can you find a majority who is being robbed of victory here?

No, but if  21 or more of  the C voters also defect the sincere BC 
majority solid coalition is robbed of victory and
the sincere majority loser wins.

> I've repeatedly asked you to show that Approval and CR pass or fail 
> Condorcet's Critrerion, by your fictitious-ranking approach. You never 
> did. I asked Chris. He couldn't either. 

In your example say the 'intended rankings' are
40: A
29: B>C
31: C>B

On these intended rankings, C is the CW. On arriving at the polling 
place we pretend that those who
were intending to rank B>C or C>B are surprised to find that they have 
to use 2-slot ballots, so they each
make an arbitrary choice whether to approve (consistent with their 
intended rankings)  one candidate or two.
This could result in these actual cast approval ballots:

40: A
29: B
10: CB
21: C
Approvals: A40,  B39,  C31.

A wins, failing Condorcet.  (This is the same set of cast ballots as in 
the "defection backfires because of too
many defectors" example).

Chris Benham

> I

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