[EM] Ammendment Methods (was: Vote Aggregation Methods)

[Olli Salmi]

At 02:53 -0000 22.2.2002, DEMOREP1 at aol.com wrote:
>http://users.erols.com/aejohns/node4.htm
>
>Another recent site about election methods.

Thank you, dear DEMOREP1, very much for this link. It addresses my question
to this list in January 1998. I described various systems of voting on
amendments. My chief worry was this: "I'm very dubious about the French
system, because the voters can't put the amendments in an order of
preference and they don't know which the alternatives are in a given vote.
It might spread into Finland. Do I have cause for worry?"

Quoting Lorrie Cranor (the current URL is
http://lorrie.cranor.org/pubs/diss/), Johnsrud mentions the following
relevant procedures:

>The Amendment Procedure

>The amendment procedure is widely used for parliamentary and board room
>voting. This procedure pairs the proposal under consideration with the
>status quo. If a variation on the proposal is introduced it is paired with
>the proposal and voted on as an amendment prior to the final vote. If the
>amendment succeeds, then the amended proposal is eventually paired with
>the status quo in the final vote. Otherwise, the amendment is eliminated
>prior to the final vote. This procedure is not neutral because it favors
>the status quo in the absence of a Condorcet winner.

>The Successive Procedure

>Unlike the amendment procedure, the successive procedure is neutral.
>However it does not select any winner in the absence of a Condorcet
>winner, and may sometimes select no winner even when a Condorcet winner
>exists. In this procedure the candidates are considered one at a time
>until one has received the majority of votes or the list of candidates has
>been exhausted. After the list has been exhausted the procedure may be
>repeated (with the hope that some of the voters may change their votes) or
>another procedure may be used.

End of quote.

The amendment procedure is the one used in English speaking countries,
where only one motion or amendment can be before the meeting at one time.
In other countries all the motions and amendments are voted upon at the end
of the debate. The chair proposes the order for voting, but the meeting can
change it. In Finland the vote is always between two alternatives. The
proposal that gets the majority is put against the next one until each
(each pair) has been voted upon. The final winner is not voted upon unless
there's been a specific motion to reject.

My understanding is that if there's a Condorcet winner this system finds
it, regardless of the order of voting. Am I right? Strategic voting is not
unknown in Parliament, so I presume it will affect the outcome.

The successive procedure is the French procedure (this is not the official
name, I'm just presuming it originated there), which is used in the EU, UN
and most other international organizations, as well as Denmark, Germany and
Austria, at least. The order of voting is the same as in Finland, the
amendment that is most different from the main motion is voted upon first
and then the next amendments in a descending order of difference, but the
vote is always for or against, not between two alternative amendments. The
voting is stopped if an amendment gains the majority. This is the part I
don't understand: I wouldn't know what strategy to use because I dare not
vote for my second preference if my first preference hasn't been voted on
yet.

Suppose I'm in a Globetrotters' Club that wants to make a trip. Stockholm,
London, Dublin, Madrid and Rome have been proposed and seconded. I prefer
Dublin and Rome is my second choice. The voting order would probably be
Madrid - Rome - Dublin - London - Stockholm, determined by distance or
cost. With the French procedure I wouldn't want to vote for Rome because it
might gain the majority before I get to vote for Dublin.

This must be the Favourite Betrayal Criterion. I think that this is a real
problem, quite apart from the possible failure of the procedure to produce
a winner. Can it affect the outcome and what strategy should one use? I've
once voted in a class with French students and it was difficult. I shouted,
rather rudely, "We need an alternative" at every point. I was given one but
the next day the vote was cancelled because it had been done wrong.

In 1998 DEMOREP1 suggested in his reply that one should check first which
alternatives have a majority of yes votes (sort of approval?), and then:

"The Condorcet method would then do the head to head pairings of all of such
majority approved issues. If one issue beats each other, then it should be
adopted.

If there is not a single beats-all winner with 3 or more majority approved
issues (as may be likely), then I suggest that the majority approved issue
with the lowest number of first choices should lose.  The head to head math
would be redone. Repeat the cycle until there is a single winner."

If I understand this correctly, there's no problem of strategy here, but
there's again the possiblity of getting no winner and the number of votes
could be increased. Also, there are occasions where I think we definitely
need a winner.

The procedures could be tweaked, of course. If the winner were the *last*
proposal to gain majority in the French procedure, I think I could handle
the strategy.

Olli Salmi