[EM] 1-seat Cumulative isn't FPTP?

[Richard Moore]

MIKE OSSIPOFF wrote:
> * That all voters should have the same weight of voting power
> 
> I reply:
> 
> All voters have the same voting power in Approval. Any voter has the
> power to cancel out any other voter's ballot. All voters have exactly
> the same voting options. All voters have the same power. A voter doesn't
> gain power by voting for more candidates. How much power is wielded by
> the voter who votes for all the candidates in Approval? The voter who
> votes for more than one candidate is a voter who's forced to compromise.
> What's more powerful about that? No one seriously claims that CR
> gives some voters more power than other voters. Approval is a point
> system in which we can give to any candidate either 1 or 0 points.
> 
> No one has more power than anyone else in the matter of whether or
> not Smith will get more votes than Jones.

I notice IRV supporters do like to distort the truth about approval.

Another way to look at Mike's point is that an approval ballot presents
exactly one vote in support of each candidate that the voter approves,
and one vote against each candidate that the voter disapproves. A vote
is a vote, whether it's for or against a candidate. A "for all candidates"
ballot or an "against all candidates" ballot may have zero effect, but
since the message carried by such a ballot is that the voter has no
preferences, then why shouldn't the effective weight of that ballot be
zero?

Contrast lone-mark plurality: If a voter wants to vote against candidate
Z, and finds all other candidates reasonably acceptable, he or she must
split his "against" vote among N-1 candidates. The lone-mark constraint
makes this method asymmetrical. The result is less equitable; in terms
of ballot "weights", plurality favors a voter who finds only one candidate
acceptable over a voter who likes more than one candidate or who strongly
dislikes one or two candidates in particular, because the latter is forced
to vote against some candidates that he or she supports.

A similar thing happens in IRV: If I find two candidates acceptable, I
have to rank one of them second, and if I choose the wrong one to rank
second, I could be contributing to the early elimination of what might
otherwise be the winning candidate, so I am voting against that candidate
(quite possibly without sufficiently helping the candidate I rank first).

And Mike is right about single-winner cumulative voting. It is equivalent
to FPTP when each voter applies optimum strategy. It is never to a voter's
advantage to split his vote between the candidate with the highest
strategic value and a candidate with lower strategic value; that only
lowers the strategic value of that voter's ballot.

> You continue:
> 
> * That the winning candidate should have a majority of the total votes.
> 
> I reply:
> 
> We've discussed at length the silly IRV definition of majority,
> the definition that says that an IRV winner has a majority
> if a majority prefer him to one other candidate, when only considering
> those two :-)

Another good (even if not new) point by Mike that I wish to second.

We know that majorities can be contradicted by other majorities. We would
risk embarassment if we started with the assumption that the winner must
have majority support, and then advocated a method that, even in the absence
of cycles, allows a winner with as many as N-2 majority defeats; but IRV is
just such a method.

  -- Richard

----
For more information about this list (subscribe, unsubscribe, FAQ, etc), 
please see http://www.eskimo.com/~robla/em