With apologies to New Zealanders’ somewhat complicated memory of Robert Muldoon, I am sticking to my “piggyback MPs” as a preferred term for members elected under MMP via an alternative threshold to the one based on party-list votes.
Here I want to address briefly the question of whether allowing an alternative threshold, by which a party qualifies for list seats through the winning of one (or more) district seats, is itself a problem in electoral-system design. I have been wanting to address this issue for some time, and some of my thoughts are anticipated by a comment left by Rob at the previous thread.
Up front, let me state that I see no problem with the principle of an alternative threshold. If mixed-member proportional systems are to have a chance of delivering on the “best of both worlds” promise, then one really should allow both worlds to coexist simultaneously. One of those worlds is one in which local concentrations of support for particular parties or candidates are able to attain representation. The other world is one in which only nationwide levels of support for particular parties are worthy of representation. Any one of us might prefer one conception of representation over the other, but MMP is explicitly designed to promote both.
Now, one might respond that one need not have the alternative threshold in oder to obtain both of these worlds. Parties could still exist to target one or a few district seats, and earn their representation that way, without being entitled to any list seats.* I concede that this is a perfectly valid argument, and it seems to be the position taken by the New Zealand Electoral Commission in its MMP Review. That is fine; they have thought much more about these issues, and the needs of New Zealand society, than I ever can do.
However, I think it is a perfectly valid “best of both worlds” provision to say that we want to give incentives to smaller parties to attract support outside their district-based strongholds, while still being able to win representation based on their regional concentration. A very small party may have supporters around the country, but be concentrated in one area. Voters outside the areas of strength have little reason to vote for the list of such a party if it won’t win seats; by the same token, voters in a single district where the party has local strength may have little reason to vote for the party if it lacks any chance to win further seats via list votes obtained elsewhere. (If one seat is expected to affect the balance of power, the second consideration vanishes, of course.)
It seems to me that the decision whether to abolish the alternative threshold should be made not on the basis of disliking particular parties that take advantage of it. (Search on “Key cup of tea” if you are unfamiliar with the debate.) Rather, it should be taken after considering what minimal size of party is considered optimal in a given country’s proportional system. (One can never squeeze out all one-seat parties, as they are at least a latent possibility in any system that has single-seat districts, including mixed-member PR, but one can eliminated the opportunity for such parties to exist to seek additional seats via the list.)
What is the optimal minimum size for parties that win more than just a given district (or two or more), but also win list seats?
I do not know! I will say that there is something fundamentally strange about the current New Zealand thresholds. If you are a party that can’t win a district, you need 5%, which implies 6-7 seats as your minimum. However, if you can win one district, you need only about 1.4% of the list vote to get two seats. The problems of these widely disparate thresholds became apparent most starkly in 2008, when New Zealand First won no seats despite 4.1% of the party vote, while ACT New Zealand won five seats on only 3.7% of the party vote. The difference was, of course, that ACT won an electorate (Epsom).
I would recommend bringing the two thresholds closer together. Any specific proposal would be arbitrary, but then so is the very idea of a nationwide threshold. I might suggest something like 3% (instead of the current 5%) party-vote threshold.** In a 120-member parliament, this would be equivalent to about four seats. Then I’d suggest an alternative threshold, the surpassing of which would entitle a party to list seats, of either one seat and 2% of the list vote, or else require two seats.*** (De-facto, the latter would mean a party needing to clear around 2.5% in order to get more than its two seats; so I would then see no need to specify any party-vote threshold.) Whatever might be chosen, I would suggest the goal should be to bring the two types of threshold closer to one another, based on a consideration of what size is deemed appropriate for a party that is more than just the sum of however many districts it can win.
Basically, I just do not see anything wrong with the concept of having an alternative threshold under MMP. I can understand why some folks would disagree, and I don’t think abolishing the alternative threshold undermines MMP. My point is that having such a threshold is perfectly consistent with MMP, and if one disparages small parties piggybacking on the support of one electorate MP (who might get elected due to explicit or tacit deals with a larger one) then maybe one really should prefer a non-mixed form of PR. That is, maybe that is an argument for being more anchored in one “world” of electoral systems, rather than trying to have the best of both. And there is nothing wrong with thinking only one of these worlds is “good” at delivering representation! Here we really are in the realm of values, not strictly objective criteria.
* This is what the Maori and Mana parties have done, with the former having won multiple districts in recent elections. This is feasible only because of a further “twist” in the New Zealand electoral system, which predates MMP: There are two layers of single-seat districts, one for the general electorate and one set aside for voters who claim Maori ancestry and choose to vote for candidates in these districts instead of the general electorates. Note that the principle of some parties winning based on the ability to win one or a few districts, but having no realistic chance to earn party-list seats, is generalizable beyond the parties representing Maori voters.
** The Electoral Commission said that 3% would not cause any problems, but came down in favor of lowering it only to 4% (see its MMP Review, Final Report, p. 16, paragraph 1.28). Interestingly, the Commission cites Taagepera and Shugart’s (1989) stated preference for reforms to be incremental as justification for not recommending lowering the threshold below 4%.
*** Germany’s thresholds are, of course, either 5% of the list vote or three district wins. Note that 3 out of 200-325 total districts (depending on the time period) is very roughly “equivalent” to New Zealand’s 1 out of 60-70 districts. However, it is probably more difficult for a very small party to have as many as three candidates capable of winning district pluralities than it is to have one, even holding constant the aggregate levels of support needed. Unless, that is, the party is exploiting a specifically regional cleavage.