[Election-Methods] "Later no harm" confusion

[Warren Smith]

>Diego Renato: I think that any method that
violates later-no-harm (except asset voting) is likely to provide incentive
to bullet vote and became a costly version of plurality.


--REPLY:
careful.

1. It has sometimes been claimed, falsely, that IRV, because it enjoys
"later no harm" offers no incentive to truncate your
preferences (and to "bullet vote," i.e. vote plurality-style).

A counterexample is
http://www.rangevoting.org/rangeVirv.html#BramsEx
see point 2 to see how the last voter type is better off bullet-voting.

2. So you (Diego Renato) should realize that "later no harm"
is actually NOT the property you actually want.  "Later no harm" is
a property artificially created to make IRV look good, not a property
created because it is inherently what is desirable.
I think Renato actually wants something
else: some kind of "no incentive to plurality-vote" property.

3. For voting methods whose ballots are NOT just rank-orderings,
(e.g. approval and range voting) there is no such thing as "truncation."
But it still is possible to cast a plurality-style range or approval vote.

Will range and approval voters, therefore, just plurality-vote?
No.  We know that does not happen because it doesn't happen.
Here are some range voting and/or approval voting election data

http://www.rangevoting.org/OrsayTable.html
http://www.rangevoting.org/FrenchStudy.html
paper #82 at http://math.temple.edu/~wds/homepage/works.html

in all these real-world studies,
plurality style voting was quite rare, well in the minority.


-- 
Warren D. Smith
http://RangeVoting.org  <-- add your endorsement (by clicking
"endorse" as 1st step)
and
math.temple.edu/~wds/homepage/works.html