What is the "consensus" by the "experts" about the best single-winner voting system?

(Executive summary)

The unfortunate reality as of 2006 is that there is no visible consensus among either political scientists, economists, or mathematicians about the best single-winner voting system. But there should be, and we think there ultimately will be, a consensus for range voting.

The usual impression one gathered from political science books up to 2000 was there were 4 main branches of single-winner systems, namely, Borda, single transferable vote, Condorcet, and approval voting – with few people (and fewer, if any, books) willing to stand up and say one of them was the best – and almost nobody in that literature said anything about range voting whatever up to just a few years ago (well, see this history for some examples...)

Now that indecision was justifiable since all four of those systems do seem best in computer simulation studies &ndash depending on the "settings" of the simulations. (E.g. see Merrill's book.) In other words, computer simulation studies were incapable of reaching an unambiguous conclusion that one of these four was the best; you can construct plausible election situations where each seems better than the others. Furthermore, philosophical comparisons also were not capable of reaching such a conclusion, because people kept disagreeing.

That changed with my computer-sim study in 2000 (#56 here) which was the first to include range voting as a contender. It used Bayesian Regret as its yardstick, and found RV was always superior to all four of the above main voting system branches at every setting (of 720 tried) in my sims. So that in some sense gets rid of the indecision and provides a clear best: Range Voting. My study also pointed out that "Arrow's impossibility theorem" which was often interpreted to mean "no 'best' voting system can exist" actually does not apply to range voting, since according to Arrow's (foolishly too-restrictive) definition RV is not a "voting system." But that information has not yet fully percolated into published political science books and the general zeitgeist.

Now besides me just telling you my impression about my view of the consensus thinking (above), there is this objective evidence. I examined the bylaws of professional associations in the field and found:

APSA (American Political Science Assoc):
its constitution mandates IRV (transferable vote) for presidential election (but so far, no election in which IRV was actually invoked has happened, so it's been kind of irrelevant... voting method choice is not an issue unless at least 3 election outcomes are possible.) Also we should note that this constitution was written before any political scientists first invented (in 1976) Approval Voting. Hence it cannot be interpreted as a judgement by the Political Science community that IRV is superior to Approval, although it might be interpreted as a judgement IRV is superior to Borda, Condorcet, and Plurality.
AAAS American Assoc. for Advancement of Science:
Bylaws specify "votes" but do not specify which voting method is to be used in situations with more than 2 choices available. (Such lack of specification is quite common in many organization bylaws.)
EPCS (European Public Choice Society):
Uses plurality voting. (Founded 1972.)
IEEE (Institute of Electrical and Electronics Engineers, world's largest professional society):
Used Approval Voting 1987-2002 but then reverted to plurality voting. (Story recounted here.)
Public Choice Society:
It has no formal membership. Although it always has a president, as far as I know until 2006 there never had been a competed election for president. But then the 2004-2006 president, Prof. Steven Brams (noted Approval Voting inventor and advocate) got them to adopt Approval Voting. They then held their first-ever genuinely-competed election (to elect their 2006-2008 president) using AV.
AMS (American Mathematical Society):
Formerly used Transferable Vote, but then switched to Approval Voting to elect its officers.
INFORMS (Institute of Management Science and Operations Research):
MAA (Mathematical Association of America):
ASA (American Statistical Association):
SCWS (Social Choice and Welfare Society):
All of the above four organizations use Approval Voting to elect their officers.
United Nations:
Uses a form of Approval Voting to elect the Secretary General.
Econometric Society:
NAS (USA National Academy of Science):
Both of the above organizations use approval voting to elect "fellows."
Olympics:
Range voting (essentially) for judging events.

As far as I know no professional society whatever uses Range, Borda, or Condorcet voting – but Debian (Linux software developers) uses Schulze's beatpath method (which is a complicated Condorcet method) conducted electronically via special software, and many internet sites use Range Voting, e.g. AllRecipes.com, Yahoo movies, Amazon.com, Hot or Not, Newegg.com, internet movie database, etc; and academia worldwide long ago reached a "consensus" on 0-100 and A-F range voting for use in grading students and selecting valedictorians. RV is also used by the Seattle commercial co-operative Madison Market.

Verdict: based on the above, if there is any professional consensus (which there isn't) it would be for Approval Voting, which is the maximally simple degenerate case of Range Voting (which is also fairly highly supported academically).

Further, it would appear from the above that if there is a professional consensus against something, Condorcet and Borda are them, with an especially bad knock against Borda. However Mathematics Professor Donald G. Saari is a noted Borda advocate and was infuriated by the SCWS's adoption of Approval Voting. (I do not know of any other noted Borda advocates besides Saari.)


Return to main page