[EM] Arrow's Condorcet Criterion

MIKE OSSIPOFF nkklrp at hotmail.com
Sat May 14 21:41:38 PDT 2005


Russ quotes Arrow's Condorcet Criterion:

Folks,

[...]

"that a
candidate who receives a majority as against each other candidate should
be elected."

Did you get that, Mike? He *assumes* a ranked ballot, just as I
suggested, and which you tried to ridicule me for.

I reply:

Actually no, I don't get that. There's nothing in that definition that tells 
us that Arrow assumed a ranked ballot.

And when you say he "*assumes* a ranked ballot" you're completely unclear 
about whether you mean that Arrow wants his criterion to apply only to rank 
methods, or whether he wants it to apply to nonrank methods and for them to 
fail it. You're quoting Arrow's definition, commenting on what you think 
that it means but doesn't say, and aren't even clear about what you want to 
tell us you think it means.

As I said before, most likely most people expect Approval and Plurality to 
fail CC, but you certainly haven't shown that with that quote--if that's 
what you were trying to show.

Russ continues:

And where is the
gobbldy-gook about sincere preferences, Mike?

I reply:

Did I say that Arrow proposed preference criteria? I have no idea if any of 
his criteria mention preference, and I've made no statements about that.

But maybe what Russ means is that preferences shouldn't be mentioned unless 
Kenneth Arrow says it's ok :-)

I'm just guessing, but maybe, to Russ, gobbldy-gook means anything that Russ 
thinks shouldn't be said. It would be better if Russ could use terms whose 
meaning is better known than that. But saying "Nonrank methods fail this 
criterion because I say so"--that isn't gobbldy-gook?

Russ continued:

Or the notion that the CC
should apply to all methods, ordinal or not?

I reply:

Russ apparently thinks that universal applicability isn't desirable unless 
Kenneth Arrow says so :-)

Russ continued:

I realize that you are a legend in your own mind, Mike, and you probably
consider Kenneth Arrow a simpleton

I didn't say that Kenneth Arrow is a simpleton. I merely said that most 
voting system academics do a very poor job of saying what they mean. Thanks, 
Russ, for confirming that statement with your quote of Kenneth Arrow's 
definition.

Mike Ossipoff

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