[EM] Query for one and all

[John B. Hodges]

>From: "James Gilmour" <jgilmour at globalnet.co.uk>
>Subject: RE: [EM] Query for one and all
>JBH asked:
>>  My question, for one and all: Is there any desirable quality, that
>>  any single-winner method has, that this method does not have?
>
>Two problems.
>1. Your second and subsequent preferences count against your first preference.
>2. If more than first preferences have to be counted, the value of 
>the votes of different voters may
>be different if the voters truncate after different numbers of preferences.
>James
>
>-__--__--
>
>
>From: Markus Schulze <markus.schulze at alumni.tu-berlin.de>
>Subject: Re: [EM] Query for one and all
>(snip)
>Condorcet, Condorcet Loser, Consistency, Independence of Clones,
>Reversal Symmetry, Smith, later-no-harm, Participation.
>
>Markus Schulze
>--__--__--

(JBH) These are exactly the sort of replies I was hoping to get. But 
I must ask for further explanation.

James: (1) would seem to be true of all methods that allow voting for 
more than one candidate. But with MCA, as with IRV/STV, your 
later-choices do not come into play unless your first-choice has 
failed to win. So, (1) is much less true of MCA than it is of plain 
Approval. (2) is true of any method that allows truncation; since it 
is at the voter's discretion, I see no grounds for complaint.

Markus: Condorcet and Condorcet loser I had already surmised. "Smith" 
sounds like another Condorcet-type of qualification; always chooses a 
member of the Smith set, I would guess. Consistency: is there any 
method that passes this, other than Plurality? Do I remember right, 
this is the ability to divide the electorate into parts, and if each 
part elects A, the combined whole elects A? How does MCA NOT pass 
that? Please remind me what "Reversal Symmetry" and "later-no-harm" 
mean, why they are desirable, and why MCA does not pass them. Much 
Thanks-
-- 
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John B. Hodges, jbhodges@  @usit.net
Do Justice, Love Mercy, and Be Irreverent.