Comments on: Tactical Voting

By: Ken Bloom

Ken Bloom — Thu, 09 Aug 2007 14:32:45 +0000

Please see http://web.archive.org/web/20021123063756/http://electionmethods.org/ (particularly http://web.archive.org/web/20020213112823/electionmethods.org/evaluation.htm) for comparisons of the mathematical properties of election methods. I agree with posters 1 and 2 who say that Condorcet is better.

Additionally, Concorcet can be computed faster than IRV (in a country of 200 million people, this is no small thing), and ballots can be aggregated into a matrix of counts, an operation that is associative, communtative, and distributive, which means it can be performed during the election as ballots are coming in, even as they are cast. And it can be done by map-reduce. You can’t do any of that with IRV.

By: Jackson Boyd

Jackson Boyd — Wed, 08 Aug 2007 15:07:53 +0000

You’re right. There’s this manic fringe in the U.S. that thinks alternatives like approval voting and range voting are The Answer to reformers’ problems, but can’t get their minds around the fact that it’s transparently obvious how to game their systems (e.g, you should bullet vote, pure and simple, or you may well hurt your first choice), while it’s quite opaque how to try game IRV. That’s why it has such a long history of success in major national elections and major non-governmental elections without complaints of tactical voting, while approval voting doesn’t work very well where it’s used in non-governmental elections and has zero support among elected officials and grounded reformers pretty much everywhere in the world.

They will even say “runoffs work just fine,” not being aware apparently that the math of their alleged “spoiler” problem with instant runoff voting is just the same as it with runoffs.

By: Anonymous

Anonymous — Wed, 08 Aug 2007 14:34:14 +0000

IRV and Condorcet require exactly the same information from the electorate. You say that “getting the average voter to use Condorcet would essentially be an IQ test as a pre-requisite to voting (numbering all the candidates in order for IR is difficult enough)”, but Condorcet requires precisely the same thing: numbering the candidates in order.

The only difference lies in how it uses the information: IRV ignores any preferences you have other than your first choice, until it eliminates your first choice, while Condorcet always takes all of your preferences into account. For instance, if you vote A, B, C, in order of preference, IRV will treat that as “A” unless it eliminates A, and IRV will ignore that you prefer B over C. This can then allow IRV to eliminate B before C, even if a majority of people prefer B over C, if most of those people don’t list B as their first choice. Thus, if you care about having B win over C, you do have to decide whether you really want to rank A first or B first, rather than listing your real preferences.

For the record, I wrote that explanation of a flaw in IRV entirely from memory, without consulting any references. I don’t think the average voter would have trouble understanding that explanation either.

By: Adam

Adam — Wed, 08 Aug 2007 13:50:36 +0000

“[...] getting the average voter to use Condorcet would essentially be an IQ test as a pre-requisite to voting (numbering all the candidates in order for IR is difficult enough).”

Um, but all a voter has to do for Concordet is number all the candidates in order. How would using Concordet to figure out the results of the vote make things any more difficult on the voters?

And the basic idea behind Concordet isn’t that hard to figure out. The only difficulty arises when there’s a circular tie, at which point one option is to just use IRV for the Smith set (the smallest set of candidates such that every candidate in the set can beat all candidates outside the set).