Tyler Cowen in an aside at Marginal Revolution.
Most countries don’t use range voting. Ireland and Tasmania have had some experience with the Single Transferable Vote (STV) system. What happens is that a bunch of candidates run for each post, party identification is weak, and reps emphasize constituency service. That’s probably the major dominant effect, namely that most systems of range voting weaken political parties.
Not quite so, I don’t think, having spent a reasonable amount of my youthliving under, voting in and studying the Irish STV system (although I am not a parties scholar – Matthew Shugart or Simon Jackman may have better and more sophisticated things to say). The effect on constituency service is undeniable – Irish politicians neglect parish pump politics at their peril, and typically compete on the number of fixes, medical cards etc that they can deliver to their consituents. But this has typically gone together (at least until the very recent past – we will see what happens in the next election) with strong, and indeed near-tribal levels of party identification. Voters have typically strongly identified with the one or the other party. Fragmentation of the party system has been relatively low – while smaller parties occasionally emerge as challengers, they are usually re-absorbed into one of the three main parties sooner or later if they do not wither away of their own accord. There have been (I think – am not sure where to find the figures on this) more independents in the Dail (Irish parliament) in recent years running and winning on single local issues such as hospital location etc – but they usually are implicitly identified with the one or the other of the main parties, and tend to vote the party line on issues other than the one that they have run on.
Dail voting takes place under a whip, with punishments of suspension or expulsion from the party for TDs (members of the Dail) who vote against the party line. There are high levels of intra-party competition among TDs and potential TDs within constituencies – the most serious threat that a TD faces is from ambitious members of her own party who would like to take her seat. However, this competition usually involves a combination of appeal to local loyalties and constituency service. It does not lead to ideological division, or (usually) to a weakening of the party on the national level.
None of this is to say that Tyler is wrong, necessarily – but one of the few significant empirical examples we have would seem to argue that quite strong parties can be maintained in an STV system. Whether this is an aberration or a manifestation of some deeper logic of STV (when combined with other specific aspects of party competition) is very hard to say, given the tiny N that we have.
Update: See further John Coakley and Michael Gallagher’s book-length survey on Irish politics.
In this regard, the Irish experience would seem to run counter to the widely held theory that PR-STV leads to weaker party discipline and party organization. … Taagapera and Shugart argue that “if strength of party organization is desired, STV is inapprorpriate, because either list PR (even with preference voting) or plurality (in the absence of US-style primaries) gives far more leeway to party elites in deciding who the party’s representatives may be.’ … Katz … puts forward a more absolute version of the theory, hypothesizing that ‘Where intraparty choice is allowed, parliamentary parties will tend to be disunited’ … Blais pushes the argument even further: ‘There is strong evidence that the single transferable vote leads to a weaker party system … Electoral competition within the party hinders unity and cohesion … the single transferable vote, like preferential voting in general, is detrimental to the development of a responsible party system.’ … Both authors point to the prevalence of intra-party personalistic competition in the area of constituency service as evidence for their theory. However, both are also forced to declare that the equally evident unity of Irish political parties is ‘illusory’ (Katz …) and ‘superficial’ (Blais …). Neither author explains what illusory or superficial party unity is and neither provides evidence to demonstrate its existence or its consequences. It would seem more sensible to note that intense intra-party competition in the area of constituency service can coexist with a very substantial degree of party cohesion and party discipline, and that the latter are products of constitutional structure and inherited modes of politics and are not undermined by PR-STV.
So in short – many political scientists agree with Tyler – but Ireland is a highly awkward case for their arguments. Also, I should note that I hadn’t read Coakley and Gallagher before writing this post to my shame (I do know John, but haven’t been keeping up with the literature on Irish politics in the last decade or so), and that the striking similarity of our arguments should be taken as an indicator of how compelling the empirical evidence is on this question, rather than as a product of groupthink.