How MMP could crash

Ideas are flying left and right for changing the constitutional system. I’ll get to them at some point, but right now those proposals are so vague that I can’t analyze them. Instead, let’s look at a much more mature proposal, the one to change the electoral system to a Mixed Member Proportional (MMP) system.

First, let’s review some vocabulary. A mixed member system combines two types of electoral formulae. In one tier, voters can vote for individual candidates. This is called the “nominal tier,” since you usually vote for a particular name. In most mixed systems, the nominal tier employs single seat districts. In the other tier, voters select a party, and parties designate individuals to sit in any seat that the party wins. This tier almost always uses some sort of party list, so it is called the “list tier.”

There are two major types of mixed member systems. In Mixed Member Majoritarian (MMM) systems (in Chinese often labeled 兩票並立制) the tiers are unlinked, so what happens in one has no effect on how the seats are handed out in the other. Taiwan, Japan, and Korea all have MMM systems. To illustrate, imagine a country with 200 total seats, half in each tier. There are four parties who win 40%, 30%, 20%, and 10% of the votes respectively.

District votes 40% 30% 20% 10%
District seats (A) 76 22 2 0
List votes 40% 30% 20% 10%
List seats (B) 40 30 20 10
Total seats (A+B) 116 52 22 10
Seat share 58% 26% 11% 5%

Since Party A is the most popular party, let’s imagine that it will win most (76) of the district seats, Party B will win most of the rest (22), and Party C will win the remaining two seats. In the list tier, the seats are distributed to each party proportionally according to the list vote. The overall seat distribution is simply the sum of the two tiers. In this example, Party A wins a clear majority of the overall seats even though it won far less than 50% of the votes. This is what we call a manufactured majority, and it is quite possible in MMM systems. (The KMT holds a manufactured majority right now; it did not get 50% of the votes in either tier in 2012.) This is why the system is labeled with the third M, “majoritarian.”

The other flavor of mixed member systems is called Mixed Member Proportional (MMP; in Chinese usually called 兩票聯立制). In MMP, the two tiers are linked. The list tier vote is much more important than the nominal tier vote, as the party vote determines the overall seat share. Using the same example from above, the seats are distributed as follows:

List votes 40% 30% 20% 10%
Total seats (A) 80 60 40 20
District votes 40% 30% 20% 10%
District seats (B) 76 22 2 0
List seats (A-B) 4 38 38 20
Seat share 40% 30% 20% 10%

Start by looking at the party list votes. Since Party A got 40% of the list tier votes, it will get 40% of the total seats, or 80 total seats. In the nominal tier, Party A has won 76 seats, so in order to get to a total of 80, it needs an additional 4 seats. Note that Party A gets the most party list votes, but it actually gets the fewest party list seats. Under the MMP logic, winning more districts doesn’t help a party win more total seats, it only changes which people get to sit in those seats. If Party A had won a 77th seat by beating one of the Party C district winners, it would have only won three list seats. Party C would have then gotten a 39th list seat. Either way, Party A gets 40% of the total seats and Party C gets 20%.

So the biggest difference between MMM (Taiwan’s current system) and MMP (which Tsai Ing-wen is promoting) is that MMM has majoritarian tendencies because the tiers are independent while MMP is proportional because the tiers are linked.

There are lots of arguments to be made for why MMP is better. My personal opinion is that just about anything other than a straight American-style single seat plurality system would be better than Taiwan’s current MMM system. However, I’m not going to go into these arguments right now. What I want to look at now are the arguments for why MMP won’t work. The concern is not that MMP will produce bad politics, but rather that, if we are not careful, MMP could simply self-destruct. Most of these concerns center around “overhang seats.”

Go back to the previous example. What if, instead of winning 76 district seats, Party A had won 82? Its 40% list share vote only entitles it to 80 seats, so perhaps it should get -2 list seats! What the Germans and most other countries using MMP do is to create overhang seats.

A B C D Total
List votes 40% 30% 20% 10% 100%
Total earned seats (A) 80 60 40 20 200
District votes 40% 30% 20% 10%
District seats (B) 82 16 2 0 100
List seats (A-B) 0 44 38 20 102
Total seats 82 60 40 20 202
Seat share 40.6% 29.7% 19.8% 9.9%

Party A is allowed to keep all 82 of its district seats, and it does not get any list seats. Party B is supposed to get 60 total seats, so it gets an additional 44 list seats. Likewise, Party C gets 38 list seats, and Party D gets 20 list seats. You will notice that this makes 102 list seats. The total chamber is thus enlarged. Instead of 200 members, there are now 202 members. Because of the overhang seats, Party A has a slightly larger seat share than vote share, while the other three parties are slightly underrepresented.

This may not seem so serious, but Germans think it is. In Germany, overhang seats have caused the parliament to expand by as many as 29 seats or about 5% of the total chamber (if my memory is correct). In Taiwan, we are used to the idea that a party’s seat share and vote share might be a little off, but Germans take the principle of proportionality much more seriously. In fact, the German constitutional court has ruled the current system is unconstitutional since it can produce such disproportional outcomes, and it has demanded that the overhang system be revamped. They haven’t finalized how they will reform the system, but one possibility is to expand the seats going to the other parties as well. In the above example, Party B might also get two more seats, and Parties C and D might each get one more seat. Thus, instead of having 202 seats, the two overhang seats might require a chamber with 206 total seats. With a lot of overhang seats, the chamber size might spiral out of control.

If this were the main problem, I wouldn’t be too worried. Taiwan has historically been willing to put up with modest amounts of disproportionality. Moreover, the modest disproportionality from a few overhang seats would be less than the average disproportionality incurred under either the current MMM system or the former SNTV system. Moreover, as long as the list tier is expanded from the current 30% of all seats to closer to 50% of all seats, we shouldn’t expect to see too many overhangs. The main reason Germany has overhang seats is that they have party lists in each state rather than one national list. If Taiwan had one list for Taipei City, the KMT might easily sweep all the district seats with less than 50% of the party vote (especially with revitalized PFP and New Parties), thus creating the potential for overhang seats. However, with a national list, the KMT’s overrepresentation in the north is balanced out by their underrepresentation in the south, so overhang seats are unlikely. (The 2008 sweep would have been just shy of requiring overhang seats.)

However, what if the KMT or DPP cynically set out to create overhang seats? Could they crash the system? Let’s go back to the first MMP example, where Party A won 76 district seats and only 4 list seats. What if Party A decided that 4 list seats wasn’t enough for their 40% list votes? What they could do is to form a fake party called Party A*. All of the district candidates would run under the Party A* label, and all of the list candidates would run under the Party A label. Now let’s look at the table:

A A* B C D Total
List votes 40% 0% 30% 20% 10%
Total earned seats (A) 80 0 60 40 20 200
District votes 0% 40% 30% 20% 10%
District seats (B) 0 76 22 2 0 100
List seats (A-B) 80 0 38 38 20 176
Total Seats 80 76 60 40 20 276
Seat share 29.0% 27.5% 21.7% 14.5% 7.2% 276

Since Parties A and A* are legally unrelated, Party A gets a full 80 list seats to reflect its 40% party list vote share, while Party A* gets to keep all of its 76 district seats as overhang seats. Of course, they are actually the same party, and instead of 40% of the total seats, they have managed to win 56.6% of the total seats. Well now, that’s quite a difference.

Of course, if Party A did this, Party B would respond with a fake Party B* and so on. The logical result is that the MMP system of 100 nominal tier and 100 list tier seats would be transformed into a de facto MMM system with 100 nominal tier and 200 list tier seats. If we change the constitution to replace MMM with MMP, we probably don’t want to end up back with MMM. Moreover, it would be dishonest MMM, all the parties would snipe at each other for refusing to honor the rules of the game, the general public would think even less of politicians’ sense of fair play, and satisfaction with the way democracy works would probably sink even lower.

Would the parties really do this? In Italy, they actually have. About a decade ago, both of the major alliances came up with fake party lists precisely to avoid having success in the nominal tier count against the list tier. Not coincidentally, Italy recently discarded its mixed member system altogether. Germans have also recently become aware of what they call “negative voting,” though they haven’t yet been cynical enough to present fake party lists. (Insert your own joke about rule abiding German culture and corrupt Italian cultures here.) I have a hard time believing that the largest party in Taiwan would see an opportunity to turn a mere plurality in the legislature into a majority and wouldn’t seize it. If Taiwan does opt for a MMP system, there needs to be some way to prevent the fake list problem. I’m not quite sure how to do this without causing all sorts of other problems.

This brings us to the second serious problem. If you do find some way to ensure that all of a party’s candidates actually use the party’s label, what do you do about independents? Consider Yen Ching-piao 顏清標. Because of Yen’s background with organized crime, he and the KMT have decided that it is better for him not to officially join the party. In the past two elections, the KMT simply didn’t nominate a candidate in his district, and Yen won as an independent. He isn’t the only one. Both the KMT and DPP have found it useful at various times to defer to independents. However, these arrangements essentially take us back to the previous problem. Any seat won by an independent will, by definition, result in overhang seats. As such, if you allow independents, the KMT and DPP have an incentive to encourage their members to run as independents (or at least not to force allies to join their party). One solution is to not allow independent candidates. In Bolivia, all candidates must represent a party, and every party must nominate a candidate for every office. I don’t think this is a plausible arrangement for Taiwan. There is a very strong tradition of independents going back to the authoritarian era. Many people consider the option to quit their party and take their candidacy directly to the people to be a basic democratic right. Again, I’m not quite sure how to square this circle.

MMP could work in Taiwan, but the details matter. If reformers ignore potential abuses, they might be burying a time bomb right in the heart of the democratic system. I’m actually starting to think that these problems are sufficiently serious that we should consider a different electoral system, such as the old SNTV system or some version of Open List PR.

14 Responses to “How MMP could crash”

  1. Klaus Says:

    Great read, especially coming from Germany. Honestly, I never ever heard anyone considering setting up A* and B* parties to play the system like this.


    Would a step like this not defuse most of the dangers and distortions you explained in the following paragraphs?

    “With a lot of overhang seats, the chamber size might spiral out of control.”

    In the most extreme example (with A* and B*), how many extra seats could that mean for the LY if the list tier is exanded to 50%?

    (Right now, isn’t Taiwan’s legislature considered too small to represent 23 mio. citizens anyway?)

    Last thought: What about a regulation that makes it obligatory for a party on the list to field a candiate in each district? So party A could still run a weak candidate and leave the more popular one to A*, but the manipulation would be much more evident to everyone.

    • frozengarlic Says:

      Any expansion of the legislature will be controversial. I think this would cause quite a bit of unhappiness in the Taiwanese electorate. Slashing the legislature in half was popular, since it seemed to punish what is often seen as an ineffective and wasteful body. I believe the legislature will be expanded in any reform, but I also think the public would be upset to find that it actually expanded by more than they (begrudgingly) accept.

      In the above example the most extreme expansion was 50%, but this need not be the upper limit. Theoretically, every nominal seat could become an overhang seat, so if the nominal tier has 70% of the total seats (as in Taiwan’s current legislature), the chamber could increase by 70%.

      The German strategy of increasing the number of list seats given to all parties in order to restore full proportionality might work. We have to assume the A* list gets non-zero votes, though this is not too problematic since every list, no matter how random, gets a few votes. If the A* list gets 1% of the party votes, then to restore full proportionality, their 76 district seats can only account for 1% of the total chamber seats. This implies a chamber of 7600 members, which is quite impossible. In addition to being far to large to effectively legislate, it would be entirely dominated by list legislators. Party B would get 2280 seats, so they might have to find a few more people to fill out their list. Fortunately, Party A plus Party A* would now only have 40% of the seats, so their incentive to work the system would be eliminated. (They would also have widespread condemnation from society for wrecking the democracy. Maybe we should be more worried about an anti-system party than a mainstream party.)

      This still doesn’t solve the independent candidate problem. Germany allows independent candidates, but it ignores the potential problem since independent candidates never win. They sometimes win in Taiwan, so we can’t ignore them.

      I think small parties would object to a requirement that every party field a candidate in every district, especially if they had to pay a registration deposit for each one. They have a hard enough time finding candidates as it is.

      There are other possible solutions, but like this one, they usually have undesirable side effects. Another possibilities are to set up a Political Party Law that restricts party switching, makes it very hard to set up a new political party, or distributes public funds only to parties that get significant numbers of both nominal and list tier votes. Again, these solutions might be more problematic than the original problem.

      • rbraun (@rbraun) Says:

        Germany does not ignore the independent candidate problem, and they learned from the Italian mistake. The new election law of 2013 (which also adds overhang seats for the other parties, as you note above) was changed with a provision to specifically fix this problem.

        If you vote for an independent candidate, AND that same candidate wins your local constituency, THEN your party-list vote gets voided. It doesn’t count. In that case, the only vote that counted for you is your winning constituency vote.

        This works because the quota of list seats in Germany is exactly 50% (300 out of 600 seats to start in the Bundestag), and the other 50% are constituency seats. So the 50% majority that presumably elected the independent (though it might have been a smaller plurality instead; this is not accounted for) elects exactly 50% of the possible amount that constituency’s voters could elect.

        Any vote over 50% is not accounted for either, and those voters don’t have any way of directing that excess to a party, either (since their accompanying party-list vote is deleted).

      • frozengarlic Says:

        Thanks, this is really fascinating. If an independent gets over 50%, how do they decide which list votes to subtract? For example, if the candidate gets 60%, do they randomly select one of every six of his or her votes (or just take the sixth on top of the pile) and cancel the list vote on those ballots? Or do they count all the list votes of people who voted for the independent and weight them all by .83?

        This fix would not work in Taiwan without another reform. In Taiwan voters have separate ballot papers for each choice (ie: president, district legislator, party list legislator), and they drop each ballot into a separate box. It would therefore be impossible to track down the votes of each person who voted for the independent candidate and invalidate their party list votes. To do that, you would need to put both district and list votes on the same piece of paper (or use computers which would keep a record).

  2. Yi-Chen Wu Says:

    Assume that the new MMP in Taiwan will result in more fake parties and more independent candidates, isn’t that a way to change the current two-party system to multi-party system? Maybe the key point would be, how loyal would those fake parties or independent be to their mother party.

    • frozengarlic Says:

      The fake party would only exist for about one month. It only needs to be organized in time to register candidates. After the election, it dissolves and the district legislators all rejoin Party A.

  3. lihan Says:

    I am confused with the Party A and Party A* example. How does party A get list votes at 40% while party A* gets district votes at 40%? Isn’t this double counting?

  4. David Reid Says:

    Very interesting analysis. In your hypothetical example isn’t it possible that Party A and Party A* would begin to compete with each other in some way. Wouldn’t that result be that the majoritarian system which favours two large and strong parties would lead to fragmentation of both sides of the political divide. Also wouldn’t some minor parties seek to gain power by joining a coalition rather than remaining loyal to their “camp”?

  5. Mike Says:

    Would it be more desirable to marry MMP with SNTV? Such that you elect the first tier of district seats with SNTV, but with much greater districts e.g. 8 seats elected from a combined district of Taichung/ Changhua/ Nantou; maybe 2 seats from a combined district of Yilan/ Hualien/ Taitung etc.

    And then use a second tier of party list seats in a way such that you preserve the total % of seats in LY = total % of votes, to fix up any minor disproportionalities of SNTV?

    So essentially similar to pre-2004 elections, but having linked tiers; but then having even larger districts/ less district seats. What impacts would such a electoral system have?

    • frozengarlic Says:

      Taiwan had a similar system from 1972 to 1986. Legislators were elected by SNTV in large districts. So Taichung City, Taichung County, Changhua County, and Nantou County were a single district. In 1986, that district elected 10 legislators. What generally happened was that candidates from the small parties (either Tangwai or DPP) ran district-wide campaigns, while the KMT and independent faction candidates rarely crossed county borders. I think the same would happen today. Given that one of the main reasons for having geographical seats is to connect legislators to a specific place, a system in which most of the legislators ignore most of their district is not ideal.

      I’m not aware of any MMP system that uses a proportional or semi-proportional system for the nominal tier. Taiwan’s 1992-2004 was a mixture of SNTV and closed list PR, but that was a MMM system rather than a MMP system. I think if you want multi-member districts and proportionality, you might as well go for a simpler PR system. Personally, I’m leaning toward some sort of modified open list system.

      Remember, there are lots of things to think about when choosing an electoral system. You have to think about what sort of incentives the system creates for personalism (which could be anything from grandstanding to corruption to developing expertise in particular issue areas) or slavishly following the party line (which I think Taiwan probably has a bit too much of right now). You have to worry about proportionally representing all parties versus the instability that many people fear comes with not having a majority party. (Personally, I fear the artificial stability and enhanced power that comes with a manufactured majority more than any instability from multi-party coalitions.) You have to worry whether the system will be easy enough for voters to understand and robust enough that strategic politicians cannot manipulate it (as in my worry about fake lists in MMP). Any system also has to fit the unique political culture of the particular place. For example, Taiwanese voters have a strong identification with county boundaries. Drawing districts that crossed county lines would probably engender significant popular dissatisfaction. More to the point, since many Taiwanese associate large, multi-county districts with the old undemocratic regime, a proposal to return to that system is probably not going to have much support.

  6. R Says:

    The council chair & vice-chair vote just ended. There were some shocking upsets for me, namely New Taipei & Tainan. While reading the news on what exactly might have happened, one thought struck me: why is the chair vote a secret ballot to begin with? Most parliamentary votes should be open for all to see I would imagine, & the DPP have to go thro heck of a lot of troubles to ensure their councilors & allies do “技術性亮票.” New Taipei have a bare majority of one councilor for the green camp, so a lost wasn’t too out of the question. What happened in Tainan I rly did not expect tho.

    It’s interesting to note how surprisingly it was in Taipei that the DPP managed a tie & barely lost. I also nvr knew in Hsinchu City there’s a pan-green alliance of independent whom control both chair & vice-chair (both whom are re-elected as well.) I must say reading about this chair election, I am both fascinated, & disheartened cuz the process seems rather undemocratic in the sense that it have a lot of potential to be manipulated by bribe.

  7. Rob Says:

    Would you be able to point out a few obvious negative aspects of Taiwan’s current electoral system? I know you have said that (just about) any other system (including the old system) is better than the current system, but I don’t really see why. From my point of view, the current system seems more straightforward than the old system. I’m sure, the current system has some negative aspects, but I think Taiwan is still working out the kinks. I’m not sure completely re-vamping the system (again) is better than trying to perfect a current system. You’re awesome explanation/analysis above shows that the alternative MMP system has the potential to be gamed/abused. If there’s a way to game the system, I’d bet Taiwanese will do it.

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