[EM] Survey of Multiwinner Methods

[Abd ul-Rahman Lomax]

At 03:24 AM 1/8/2013, Greg Nisbet wrote:
>There's some definite motivation for writing the list of criteria to 
>exclude parties, districts, and relying on candidates making 
>decisions. These sorts of mechanisms are not always available (for 
>instance, picking pizza toppings or locations or something of that 
>nature). That's not to say that these methods are never useful or 
>not "competitive" with party-less, district-less, 
>candidate-decision-less methods in some sense ... it's just harder 
>to compare their merits in some sort of "universal" sense without 
>considering very specific factors about the community associated 
>with the election. In that sense, limiting focus to methods that 
>don't impose these sorts of additional structure or requirements on 
>the candidates or voters helps to simplify things rather dramatically.

Sure. It *also* can be expected to produce results that are less than optimal.

"Relying on candidates" to make decisions is a narrow view of Asset 
Voting. Rather, Asset Voting delegates decision-making, not to 
"candidates," per se, but electors. Because we are so accustomed to 
voting for "candidates," we overlook this when we think of Asset.

In the Pizza election, obviously the Pizza doesn't decide (but that 
Mushroom-Olive pizza makes a mean argument!). But one could perfectly 
well, in a complex multiple-choice "election," choose, not the 
result, but who or what process makes the choice.

However, there is a classic method for doing this that works 
perfectly well, and it is simply supermajority rule, even consensus 
process. (If the majority feels that the group is taking too long, 
"We're hungry, dammit!" the majority can simply make its own 
decision, and invite others to join, o not.) The real point is that 
classic decision-making process is *interative*. It is not a simple 
one-shot amalgamation. In classic process, someone may say, "Let's 
get a Pepperon Pizze!" and the group shouts "Yes." Supermajority. But 
then someone says, "I really can't eat that!" And the majority will, 
in a functional social group, back up.

Range voting can be used to speed this up, but the "speed up" only 
will occur with fairly large groups, and especially groups that 
cannot meet in person. In person, Approval is the departure from 
traditional formal process that makes sense. The final key to showing 
a decent decision is a *ratification,* if there is any doubt. I've 
seen an apparent 97% A, 70% B, under Approval, turn into 100% A, no 
exceptions, when presented for ratification, but this was in person. 
This whole process can take less time than setting up and adding up 
the votes for a Range poll.

Asset can pick a result that would be *completely* unexpected, 
something entirely outside of initial consideration. Asset can be 
understood very simply: instead of making decisions only from 
ballots, delegate the final decision process to representatives, for 
efficiency. With the pizza election suppose that it develops that all 
but one member of the group *really wants* pepperoni, and one can't 
eat pepperoni. The problem with buying separate pizzas is that a 
smaller pizza, or by the slice, is more expensive. However, the 
group, if it wants to accomodate the minority person, could in fact, 
decide to by two pizzas, one small, and could present the 
contribution to be put in to be sufficient to buy both pizzas (if we 
assume equal contributions, say). Or someone could decide to 
contribute a bit more. Balancing all this, discussing it, etc, could 
be difficult, but if two people end up discussing what to do, it's 
quite possible that 100% consensus could be obtained on a result. 
Everyone would agree that the result is fair.

The universe of possible "candidates" is large!

The complexities of various voting systems arise from the 
limitations, generally, of single-poll pure amalgamation processes. 
Asset is a *generic solution,* and it works without party structures 
or districts. (Asset can work for district elections, but the 
universality of representation is damaged, that's all.) Short of 
Asset, various reformed versions of Majority have been suggested, 
with the compromise that a runoff can complete with a Plurality 
result. I've shown how a maximum 2-poll system can satisfy the 
Condorcet Criterion, for example, with an appropriate first-poll ballot.

(Esentially, range polls collect the most detailed voter preference 
information, and, with decent rules, can be interpreted as ranked 
ballots. Hence I highly recommend range ballots, which would include 
Bucklin with balanced preference options (standard Bucklin was Range 
4, but with a missing disapproved rank). Range resolution can be 
increased for larger candidate sets. And Asset could actually be used 
as a tweak to increase majority completion rates.)