# other devious electorate solutions

Steve Eppley SEppley at alumni.caltech.edu
Tue Nov 10 13:23:26 PST 1998

```Mike Ossipoff <ntk at netcom.com> wrote:
> Steve & Tom Round suggested the candidate withdrawal option
> as a solution for strategy problems for IRO, but it would work
> with any rank-method, including Votes-Against. With that method
> it would completely eliminate the order-reversal problem. An
> advantage is that since reversal couldn't ever work, it wouldn't
> be tried, and therefore the withdrawal would never need to be
> used, except maybe once or twice at first.

Even with the best (pairwise) methods, the Withdrawal option
would still be used sometimes even when voters don't
misrepresent their preferences.  Where there is a sincere
circular tie, it could be advantageous for one of the
candidates who loses the circular-tie-breaker to withdraw, if
that "improves" the outcome from his/her perspective.

(Hopefully, what the withdrawing candidate will receive in
exchange, from the new winner, is the policy plank which led a
majority to rank him/her ahead of the new winner.)

The Withdrawal option also mitigates a "problem" with plain
Condorcet-EM, that it can violate the Smith criterion (and it
can even elect a "Condorcet Loser", which is an alternative
which loses pairwise to each other alternative).  For
instance, suppose there's a 4-candidate election where A, B,
and C are circularly-tied clones and D is a Condorcet Loser:

20: ABCD
20: CABD
13: DABC
13: DBCA
13: DCAB

The pairwise tally table:
x>A   x>B   x>C   x>D
A vs B?       33    66L
A vs C?       66L         33
A vs D?       39                60L
B vs C?             33    66L
B vs D?             39          60L
C vs D?                   39    60L

D loses all three of its pairings, 39<60.
But A, B, and C all have max "votes against" of 66.
Since 60<66, if no one withdraws then plain Condorcet-EM
will elect D.

If any one of A, B, or C withdraws, D will be defeated.
Since all three appear to have an incentive to defeat D,
we can expect that one of them will withdraw.

A plausible measure of a voting method's "goodness" may be the
frequency of withdrawals.  The fewer withdrawals, the better
the method.  (We should probably also count candidates who are
eliminated in primaries, or who announce but withdraw before
the election, as "withdrawn" candidates, for comparison's
sake.)

For simplicity's sake, where the withdrawal option is allowed
I'd also wholeheartedly support methods which are simpler than
pairwise methods, even though simpler methods will make
withdrawals far more likely.  For instance, the simplest
preference voting method is "plurality wins"; combined with
just-in-time withdrawals this method would be easy to
understand, and reasonably good assuming we can rely on
candidates to not needlessly be spoilers.  (I'd also
wholeheartedly support IRO if candidates may withdraw after
the voting before the tally is finalized, but it's not clear
that IRO's iterative eliminations are truly easier to
understand than pairwise methods.  There's only an unproven
assertion of this by IRO advocates, with no evidence
supporting it.)  Eventually, as voters grasp the principles,
they will switch to more complex methods where withdrawals are
needed less.

I heard that Santa Clara County (in California) elected to
adopt IRO in county/local elections.  It would be interesting
to ask whether they will allow candidates to withdraw after
the voting, and also whether they will publish the ballots on
the internet before the tally is finalized so candidates can
calculate whether they should withdraw.  Probably neither of
these has occurred to the powers-that-be in Santa Clara.  I