[EM] Chris, DD

[MIKE OSSIPOFF]

Chris--

I'd said:

Remember that it's been shown that every nonrandom
method gives some kind of incentive for strategic
voting."

You reply:

CB: Yes, but not in the zero-info. case. I don't think
that DD(WV)'s  0-info. incentives combined with its
vulnerability to Burying and defection is the best
bargain.

I reply:

I can't agree or disagree without knowing what DD is. DD stands for direct 
democracy, but I assume that that isn't what you're referring to.

I suggest that you worry too much about 0-info strategy. Though our 
elections are now 0-info, they won't remain 0-info if Approval or Condorcet 
wv replaces Plurality.

You're concerned that wv is vulnerable to burial and defection. I'm not 
quite sure what you mean by defection, but if it refers to truncation, then 
I point out that, for the conditions described in the premises of  SFC & 
GSFC, and for the majority referred to in those premises, nothing short of 
preference-falsification can cause strategy need. In other words: No 
truncation problem.

But if, by defection, you're referring to the co-operation/defection dilemma 
that James described, then it's true that wv is subject to that problem--but 
not if ATLO is available.



"The equal-ranking incentive that you describe is
gotten rid of by AERLO."


I  am strongly of the view that as far as possible,
the result of the election should be determined purely
by the voters, who are nominally (or "in theory")
voting sincerely.

I reply:

But in methods that don't meet the defensive strategy criteria, it would be 
unrealistic to expect people to vote sincerely.


Therefore I'm opposed to explicit
strategy devices

I reply:

Ignoring strategy need won't make it go away.

I'd said:

"Still, it would be a nice luxury for everyone to
have no incentive to do other than sincerely rank
those better-set candidates."

You continue:

I am sure that SCRIRVE, and doubtless some other
methods, fill that bill.

I reply:

Doubtless some do. Margins does. Maybe SCRIRVE does too. The problem is the  
bills that they _don't_ fill. When they avoid that mild strategy incentive, 
while causing serious strategy dilemmas in which majorities are 
strategically forced to reverse their preferences or bury their favorite in 
order to protect the win of a CW or to protect majority rule, then I suggest 
that those methods are losing more than they're gaining for the voter who 
wants to reduce strategy need.

You continue:

I think the "Definite
Majority Choice" idea recently floated here of having
the voters enter an approval cutoff in their rankings
and then the method eliminates all candidates who are
pairwise beaten by more approved  candidates;  is
promising.

I reply:

Maybe some of those proposals meet Condorcet's Criterion. Probably their use 
of Approval brings some additional benefit. Probably some of them meet WDSC, 
and would therefore meet SDSC if they had AERLO. But I doubt that they meet 
SFC.

If you're going to propose a rank method, propose one that meets at least 
WDSC and SFC. Why settle for less, when the simple and modest PC meets those 
two criteria, and when SD, SSD, BeatpathWinner/CSSD and RP additionally meet 
GSFC and SDSC?

Of course it would be premature to say for sure that they don't meet SFC. 
But I don't doubt that the new methods have advantages, and I'd be 
interested in hearing more about their advantages.

Mike Ossipoff

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