[EM] IRV's "majority winner". What if we let the people choose?

[Curt Siffert]

I like this example a lot because I think it approaches the nut of what 
social choice should actually mean.

The first case is pretty uncontroversial.  What makes the second case 
interesting is that there's this psychological impact to it.

One good idea to explore is if each individual voter *knows* how the 
rest of the population voted.  If each voter only knew that the 
majority preferred C to B and A, then the population would be pretty 
satisfied with C being the winner.

But if they know the full results as stated below; that C had almost no 
first-place votes, it's only then that the results become controversial 
- even though that fact is irrelevant to Condorcet scoring.  The only 
reason the result is controversial to the population is because the 
population knows how everyone else voted.

I'm not a big math-head and don't know much about Nash, but this does 
remind me a bit of how Nash was explained in that movie.  That it's not 
so much about what is good for the individual alone or the group alone, 
as it is about what's good for the combination.  Similarly, the social 
comfort with a result isn't just feeling like one's individual vote is 
counted - it's about feeling comfortable that everyone's vote is 
counted.  The reason that the second example doesn't feel good to many 
is not because someone feels like their own vote wasn't counted; it's 
because it's easy to feel that the population got collectively screwed.

I know Condorcet pretty well by now, so in the second example I very 
much would accept C as the winner.  But it's still clearly an example 
where Condorcet doesn't shine, because what the population is really 
saying is just that they overwhelmingly want C to come in second, and 
can't really decide anything else decisively.

by the way -

> IRV winner = B;  CW wiener = C

freudian slip?  :-)


On May 15, 2004, at 3:45 PM, James Gilmour wrote:

> I wonder. Consider:
> 35  A<C<B
> 33  B<C<A
> 32  C<B<A
>
> IRV winner = B;  CW wiener = C
> I suspect most electors would be happy to accept C as the "winner" of 
> this election.
>
> Now consider:
> 49  A<C<B
> 48  B<C<A
>   3  C<B<A
> IRV winner = B;  CW winner = C.
> I doubt very much whether most electors would accept C as the "winner" 
> if this were an election for
> Sate Governor, much less for a directly elected President of the USA.  
> If anyone has evidence to the
> contrary I'd like very much to see it.
> James Gilmour
>