In replying to some parts of this message, I was a bit hasty, so Ill take
it over (Wouldnt it be great if _anything_ could be taken over?):
Pasting from Mike's page: > /Some definitions useful in subsequent criteria
definitions:/ > > A voter votes X over Y if he votes in a way such that if
we count only > his ballot, with all the candidates but X & Y deleted from
it, X wins. > > [end of definition] > > Voting a preference for X over Y
means voting X over Y. If a voter > prefers X to Y, and votes X over Y, then
he's voting a sincere > preference. If he prefers X to Y and votes Y over X,
he's falsifying a > preference. > > A voter votes sincerely if he doesn't
falsify a preference, and > doesn't fail to vote a sincere preference that
the balloting rules in > use would have allowed him to vote in addition to
the preferences that > he actually did vote. > > [end of definition] > > >
Strategy-Free Criterion (SFC): > > /Preliminary definition: /A "Condorcet
winner" (CW) is a candidate > who, when compared separately to each one of
the other candidates, is > preferred to that other candidate by more voters
than vice-versa. Note > that this is about sincere preference, which may
sometimes be > different than actual voting. > > > SFC: > > If no one
falsifies a preference, and there's a CW, and a majority of > all the voters
prefer the CW to candidate Y, and vote sincerely, then > Y shouldn't win. >
> [end of definition] > Michael Ossipoff wrote: > Kevin and Chris posted
their criteria that they incorrectly claimed > equivalent to SFC. > > These
same alternative "SFCs" have been posted to EM before and > thoroughly
discussed before. > In fact, we've been all over this subject before. So why
don't you point us to where in the EM archive we can find this earlier
discussion?
Chris asked:
Are they [votes-only, rank-methods-only versions of my criteria] in your
opinion equivalent for ranked-ballot methods?
I reply:
Yes, probably so. It seems a sure thing that theres no way that RV,
Approval or any other nonrank method could meet SFC, GSFC, or SDSC.
Though I object to the suggestion to replace my criteria with those
versions, I dont deny that someone could consider them more convenient, as
_tests_ for compliance with the criteria. As I said, when telling why I like
or dont like a method, I want to do so in terms of criteria whose wording
tells why one should want compliance. So I prefer my own preference-based
wordings of my defensive strategy criteria. However, I myself have used a
votes-only, rank-methods-only test for compliance with my criteria: Steve
Epplelys Beatpath Criterion. Any rank method that meets BC meets all four
majority defensive strategy criteria (SFC, GSFC,. WDSC, & SDSC). You could
say that no nonrank method meets BC, or you could say that its only applied
to rank methods. But its a convenient way to test for compliance with all
the majority defensive strategy criteria. BCs wording doesnt make it
obvious why it should be met, and so I prefer my criteria, as criteria. I
use BC as a test.
So I cant say that I object to the use of votes-only, rank-methods-only
tests for compliancd with my criteria, if someone finds them more convenient
to use.
Id said:
Though Chris's and Kevin's criteria clearly are not equivalent to SFC, >
maybe someone could write a votes-only cirterion that is. First of > all,
what's this obsession about "votes-only"?
Chris replied:
Some people worry that criteria that give the appearance that we have to
read voters' minds to see if they are met are not the easiest to check for.
I reply:
As I was saying, I have no objection to votes-only, rank-methods-only
compliance tests. In fact I use one myself: I use BC because it tests for
compliance with all four majority defensive strategy criteria.
On the other hand, I usually prefer to demonstrate compliance directly from
my criteria definitions. It isnt as difficult as one might expect. I
understand the objection about preferences being intangible, and how someone
might prefer to only work with votes. But preferences arent difficult too
deal with. I probably could have been clearer about that before, so let me
say it better:
First, compare the preference stipulations in the criterions premise with
the preference stipulations in the claimed failure example. Those in the
latter should be consistent with those in the former, in order for the
criterion to apply to that example.
Given the preferences stated in the example, and the voting stated in the
example, use the definitions of sincere voting and falsified voting (those
definitions use prefer) to determine whether the example is consistent
with the criterions premise stipulations about sincere voting &/or
non-falsified voting.
If the example is consistent with the criterion's premise in that and other
respects, then the criterion applies to the example. If so then check if the
example's result complies with the criteerion's requirement.
All of that can be done without using or having a definition of prefer.
(Though Ive posted to EM a precise, abstract definition of prefer).
And no mind-reading is needed, because the failure-example-writer tells you
explicitly what voters preferences are. He can, in his
criterion-failure-example, make those preferences whatever he chooses.
More work than a votes-only, rank-methods-only compliance test? Maybe, but I
consider it more effective to demonstrate compliance or noncompliance
directly in terms of my preference-based criteria. But Ive used BC as a
test to determine compliance. In fact, Ive used BC to _demonstrate_
compliance to another person, when that person asked for demonstrations for
all the defensive strategy criteria. But usually I prefer demonstrations
that directly work from the actual criteria definitions, the
preference-based definitions that, in my opinion, best tell why compliance
is desirable.
The rest of my reply was ok as-is.
Mike Ossipoff
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