[EM] IRV vs Plurality

[Juho]

On Jan 13, 2010, at 9:14 AM, robert bristow-johnson wrote:

> it still is a curiosity to me how, historically, some leaders and  
> proponents of election reform thunked up the idea to have a ranked- 
> order ballot and then took that good idea and married it to the IRV  
> protocol.  with the 200 year old Condorcet idea in existence, why  
> would they do that?

1) The basic idea of IRV is in some sense natural. It is like a street  
fight. The weakest players are regularly kicked out and they must give  
up. I'm not saying that this would lead to good results but at least  
this game is understandable to most people. Condorcet on the other  
hand is more like a mathematical equation, and the details of the most  
complex Condorcet variants may be too much for most voters. Here I'm  
not saying that each voter (and not even each legislator) should  
understand all the details of their voting system. The basic Condorcet  
winner rule is however a simple enough principle to be explained to  
all. But it may be that IRV is easier to market (to the legislators  
and voters) from this point of view.

2) IRV is easier to count manually. Condorcet gets quite tedious to  
count manually when the number of candidates and voters goes up. One  
can use some tricks and shortcuts to speed up manual Condorcet  
counting but IRV probably still beats it from this point of view.  
Manual counting was the only way to count for a long time. Nowadays we  
have computers and Condorcet tabulation should thus be no problem at  
all (at least in places where computers are available). But this is  
one reason why IRV has taken an early lead.

3) Large parties are typically in a key role when electoral reforms  
are made. Election method experts within those parties may well have  
found out that IRV tends to favour large parties. In addition to  
trying to improve the society the best way they can, political parties  
and people within them also tend to think that they are the ones who  
are right and therefore the society would benefit of just them being  
in power and getting more votes and more seats. The parties and their  
representatives may also have other more selfish drivers behind their  
interest to grab as large share of the power as possible :-). IRV thus  
seems to maintain the power of the current strongest players better  
than Condorcet does, and that may mean some bias towards IRV.

4) The problems of different election methods may appear only later. A  
superficial understanding of IRV reveals first its positive features.  
Like in Burlington the negative features may be understood only after  
something negative happens in real elections. This applies also to  
Condorcet. On that side one may however live in the hope that the  
problems are rare enough and not easy to take advantage of so that  
sincere voting and good results would be dominant. The point is that  
IRV may be taken into use first (see other points above and below)  
without understanding what problems might emerge later. And once it  
has been taken into use it may well stay in use for a long time  
(electoral reforms are not made every year, people have already gotten  
used to the method, having to change the method could be seen by the  
society/legislators as a failure/embarrassment, and people/parties who  
were elected based on those rules and are strong in that system may be  
reluctant to change the rules).

5) Both IRV and Condorcet have some weak spots that can be attacked.  
As you point out the weak spots of IRV may well be worse than those of  
Condorcet methods (for most typical use cases in politics). Different  
problems may have different weight in different political  
environments. For example in countries with strong two-party tradition  
and single party government some Condorcet properties like the  
possibility of electing candidates that do not have strong first  
preference support in the ballots may work against it (both in the  
case that one does not want the system to change and in the case that  
one wants to renew the system). Also strategic voting and fraud  
related problems (like later no harm, burial, precinct counting) may  
be seen in different light in different societies, e.g. in countries  
where strategic voting is the norm vs. in ones where sincere voting is  
the norm. One may thus have/develop points of view where Condorcet  
looks worse than IRV (I guess it could also be worse for some uses in  
some societies from some points of view).

Juho


P.S. One more reason is that Condorcet promoters seem to be lazier  
that IRV promoters :-). Condorcet has made some progress in the  
academic circles but not yet in politics.