[EM] Why IRV is popular

[Russ Paielli]

Eric Gorr recently posted a link to a one-page document by Jim Lindsay 
explaining why he and many political activists prefer IRV to Condorcet, 
Approval, and other methods.

One of Jim's "criteria" was "system easily explained." Surprisingly, he 
put "somewhat" for both IRV and Condorcet.

IRV is much easier to explain than Condorcet, and I believe that is the 
primary reason that it is more popular.

An IRV promoter simply explains that the voter ranks the candidates, and 
the first choices are counted. So far the counting procedure it is 
identical to our current plurality system. Then the promoter explains 
that if nobody gets a majority, the candidate with the least votes is 
eliminated, and any voter who had that candidate at the top of his list 
has his next choice bumped up to the top. The counting is then repeated, 
again as if it were a plurality election. The process repeats until some 
candidate gets a majority.

My point is that the counting procedure is very similar to our current 
system. The only twist is the elimination of candidates and transfer of 
votes, which most people can grasp fairly quickly.

The fact that IRV is non-monotonic and non-summable never even occurs to 
perhaps 99% of those who hear about it, and the activists who know about 
these deficiencies don't consider them important. IRV is popular because 
its rules are simple and the basic counting procedure at each round is 
identical to plurality.

The same cannot be said for Condorcet, particularly when it involves 
dropping of defeats. Just explaining the pairwise races and matrix is 
already more complicated than IRV. Then when you start talking about 
dropping defeats, people start wondering what sort of crackpot scheme it 
is. By the time you get into the actual *rules* for dropping defeats, 
the game is over. Get into "margins" vs. "winning votes" and the poor 
listener wishes he were late for a root canal.

"Traditional" Condorcet with dropping of defeats may be appropriate for 
organizations of people with a special common interest, but it will 
never be accceptable for highly contentious public elections. The Bird 
Watchers of America may be willing to agree to use defeat-dropping 
Condorcet, but a large public jurisdiction never will. And think about 
what would happen if they did: the losing side would immediately become 
biased against the method. It's just too complicated and too arbitrary.

The general public expects the rules of a public voting system to be 
simple and easily understood. The public acceptability of a method goes 
down by perhaps nearly an order of magnitude for each additional 
sentence required to explain it. That's what I think, anyway.

--Russ