[EM] 22 March, 1435 GMT, Chris: Approval

Michael Ossipoff mikeo2106 at msn.com
Thu Mar 22 07:36:06 PDT 2007

I’d said:

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.

Chris replies:

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

I reply:

Chris quotes the definition of Minimal Defense:

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 and here. 
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.

I’d said:

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

Chris replies:

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

I reply now:

I’d agree and be content with an example that doesn’t violate SFC or SDSC. I 
don’t judge methods by Minimal Defense. For one thing, it’s only about rank 
methods. I prefer criteria that compare all methods.

Yes, you’ll say that Minimal Defense compares all methods, if we tell the 
story of the voters who arrive at the polls intending to vote rankings that 
are optimized for Plurality strategy. <smiley>

But I prefer criteria that apply to and compare all methods without that 
ridiculous story. Criteria whose justification doesn’t depend on voting that 
is unexplained and rankings that are without any meaningful real-world 

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 

I reply:

That’s routine in this country.

Chris continues:

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

Approval: B53, A52, C2.

I reply:

Quite so. That’s why I say that, though for me, as an individual voter, 
Approval would be fine, millions of voters need a method that doesn’t 
require any good judgment from them--a good rank method.

As it actually happens, virtually all of the A voters vote for B, and so 
it’s easy for the media to convince voters that A isn’t “viable” and isn’t 
“a serious candidate”. The election results seem to confirm what the A 
supports have been told by their tv.

But that isn’t so with Approval. Even if all the A voters helped B, the vote 
totals still show (as they do in your example) that A outpolls C. So, though 
the voters are fooled once, they shouldn’t be fooled again. Next time the 
media try to tell them that A can’t beat C, the A supporters hopefully won’t 
believe it.

As I said, Approval soon homes in on the voter median and stays there.

SSD, MDDA and MAMPO have the advantage of getting there immediately. Also, 
those excellent rank methods require less judgment on the part of voters.

But there’s a good chance that, in Approval, the A voters won’t vote for B 
(or a candidate of B’s party) in the second election, after finding that A 
outpolls B.

Aside from all that, if B were really an acceptable candidate, if the A 
voters all knew what they were doing when voting for B, then your example’s 
outcome would be an acceptable one. If, on the other hand, B is unacceptable 
to A voters, then they shouldn’t vote for B, and then your result wouldn’t 

Chris continues:

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

I reply:

The ones that fail FBC and SFC will sometimes require voters to bury their 
favorite in order to save a compromise. But those methods will never have 
the strategy-freedom that an SFC complying method would have.

Those strategy problems can be described in terms of voters’ dire need for 
good information to inform their strategy. The more drastic the needed 
strategy, the greater the need for information. And a desperate need for 
good information, to inform defensive strategy, makes for great 
vulnerability to media disinformation.

Chris’s co-operation/defection example:

Sincere preferences:

40: A
29: BC
31: CB

The C voters vote C & B. The B voters vote only B. B wins by defection.

I’d asked:

Chris, can you find a majority who is being robbed of victory here?

Chris replies:

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 reply:

Yes. It’s a good thing that at least the C voters had  good judgment, so 
that someone acceptable to them won.

But, in the next election, The B faction will be in a poor position. After 
the defection, the A voters will have a very credible threat to bullet-vote 
(if they feel it’s that important to beat B), especially if there’s some 
reason to believe that A has more popularity than B has.

But I answered about that defection/co-operation problem in a recent 

Chris said (showing the operation of FARCS):

…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).

I reply:

All very well, for Approval. But what happens to your plausible story if the 
method is Plurality? You say that, then,  FARCS assumes that the voters 
arrive at the polls intending to vote a ranking that is optimized for 
Plurality. So your story about voters who are surprised by not having a rank 
methods doesn’t work at all, does it. Now you’re forced to tell of voters 
who arrive at a Plurality election intending to vote rankings that are 
optimized for Plurality. How much sense does it make to say that they come 
to a Plurality election intending to vote rankings, when they know that it‘s 
a Plurality election (as they must, because their rankings are optimized for 

That’s what I mean by a ridiculous story and a very inelegant criterion.

When I offer a method to the public, and tell them about a criterion 
compliance that justifies it, I don’t want to tell them that ridiculous 
story when I tell them why some methods fail the criterion. I don’t want to 
explain why the criterion appears to only compare rank methods, explaining 
it with that ridiculous story.

You and Kevin might find FARCS useful for discussing and comparing methods 
among yourselves, but I hope you know better than to actually try to use it 
with most people.

Anyone who tried to use your FARCS criteria would be laughed off the stage.

Mike Ossipoff

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