One complaint that MMP opponents sometimes make is that changing the voting system will not fix other underlying problems in our democracy. This argument is a smokescreen; I have not yet read an argument that proposes that keeping first-past-the-post (FPTP) fixes any of these problems, just that MMP doesn't fix them.
A frequent form of this complaint is the "power centralization" argument: the real problem with Ontario's democracy is that party discipline is too strong in Ontario. Everybody votes along party lines, thus centralizing government power in the hands of the ruling cabinet and especially the premier:
The central defect of our political system is that most of our provincial members and MPs in Ottawa perform like sheep, occasionally altering their behaviour to that of chickens.
Our political system is the least representative in the industrialized world. Our members and MPs don't represent their electors. They represent their parties.
They do and say, just about, whatever their party tells them to do.
-- Richard Gwyn, "Electoral Reform won't fix the real political
problems", The Record, May 22 2007.
This argument comes perilously close to contradicting the FPTP defence that our existing system allows people to vote for candidates and not parties, but let's avoid that pit of quicksand for now. My primary criticism of the power centralization argument is that MMP actually does help decentralize power.
The first good effect comes via coalition government. A big-tent party will pay all kinds of lip service to diverse interests while campaigning, but once in power the party can pursue whatever interests it wants. The opposition parties can offer some symbolic resistance, but without a majority of seats in parliament they have no ability to veto or even modify legislation. Big-tent parties in coalition governments are in a very different position; when bargaining for coalition agreements with potential partners big-tent party will often have to concede policy on issues the big party paid lip-service to but had no real intention of carrying out. The perpetual issue of foreign credential recognition comes to mind; pretty much every party promises to get foreign-trained doctors and engineers out of our taxi fleets, but nobody has the political will to make this a priority. With a coalition government issues like this could become priority issues, so long as the big-tent party and its partner(s) all campaigned on the issue.
Many of these policy concessions will happen during the initial weeks when governments are putting together coalition and/or confidence and supply agreements, but power decentralization continues throughout the lifetime of the government. When proposing policy the smaller parties are not beholden to the wishes of the premier, so there is more room for a diversity of views.
When there are major scandals or ideological confrontations between parties, the coalition runs the risk of breaking apart. This is, of course, both good and bad: it's good because coalitions will tend to break when they are least popular, and thus when people most want change. It is bad because broken coalitions can lead to early elections. (This is a large part of the reason why coalitions should be composed of a very few parties that are either large or medium-sized. Including tiny parties in coalitions is usually a bad idea because the tiny parties have lots of incentive to be yappy and break the coalition.) Breaking coalitions has its cost for smaller partners too, however. For example, the Green Party enjoyed close ties with Labour in 1999, but alienated themselves from Labour over the issue of genetically modified organisms. As a consequence, the Greens got themselves blacklisted from formal coalition agreements with Labour, although they still support Labour in confidence and supply matters. (Vowles Banducci Karp 2006)
One of the most intriguing changes in New Zealand is that under MMP there has been an increase in caucus consultation when parties draft legislation (Boston Church Bale 2003). Before MMP, the cabinet would come up with legislation, inform the backbenchers of the new legislation and order the backbenchers to vote for it. The first National government of 1996 behaved similarly, but then practices changed. Now, ministers propose legislation, then refer the legislation back to caucus members and committees for feedback and negotiation. This means that legislation is passed more slowly, but it is also drafted with more consultation and less centralization. It is not clear that this practice will carry over to Ontario, but it is a strong indication that the voting system can influence political culture.
Another way in which MMP decentralizes power is the way it reduces the stranglehold the two big-tent parties have over politics. Under FPTP in Ontario, aspiring politicians would be best advised to join either the Liberal or Conservative parties, because these parties win almost all seats in Ontario and thus maximize a politician's chances of getting elected. When the party leaders and bigwigs do stupid and/or oppressive things, aspiring and elected politicans have the choices of putting up with the garbage, trying to survive as independent candidates for an election or two (Hi Garth Turner!) or jumping ship to the other big tent party (Hi David Emerson! Hi Belinda Stronach! Hi Scott Brison!). MMP gives smaller parties realistic chances of getting seats, which allows a sufficient number of disgruntled politicians to mutiny and form a new party. The new party can win a few seats and present itself as a potential coalition partner to the big tent party it deserted (Hi New Zealand First, Progressive Party, and several other small New Zealand parties!).
Thanks to the three percent threshold in Ontario, politicians can't take this schism strategy too far, but there is no question that it will happen to some extent. This reduces the power of the big parties, and forces them to be more responsive to the diversity of interests within the party if they want to retain their membership and hold on to power. Certainly, big tent parties will continue to enforce party discipline (and it might become stronger under MMP) but the discipline can't get too heavy-handed (Hi Stephen Harper!).
Of course, the FPTP defenders will turn all of these advantages into criticisms of MMP. Party concessions get turned into backroom dealmaking; big parties listening to small ones morph into tails wagging dogs; broken coalitions are translated to endless minority governments; increased legislation consultion is interpreted as government deadlock, and the end of big-tent strangleholds mark the beginning of party splintering. Underneath the mudslinging and name-calling is a serious question: how much power should parties have, and what tradeoffs should parties face in order for governments to run most effectively. Is concentrating power in the hands of two large parties (and passing all legislative power back and forth) the best way? Should we distribute power over a plethora of parties and let them sort it out? I think that Ontario's proposed MMP system gives us a set of tradeoffs that are not bad. The two big parties will continue to have quite a bit of power, but that power will be effectively moderated by other parties. Changing the voting system will not fix all of democracy's problems, but it is one component to rebuilding a system we can trust.
There are other options, of course. If a nontrivial number of people read my blog, then no doubt an endless parade of Single Transferable Vote (STV) supporters would earnestly and politely point out that MMP is a party-oriented voting system, and that the real way to decentralize power is to adopt a candidate-oriented system... like, for example, STV. That is a valid criticism, and one I have some sympathy for, but STV is not an option this October. Either we choose MMP, or we stick with FPTP. If people want to vote for FPTP this October with the hopes that they can somehow get an STV system on the agenda later, they are welcome to do so. I have less and less faith that such a strategy would work. There are too many hurdles to overcome, and I really don't think that Ontario cares enough about electoral reform to repeat this process in the forseeable future. I am sufficiently disenchanted with FPTP and sufficiently unafraid of MMP that I am still willing to vote for change.
References
(Boston Church Bale 2003) Jonathan Boston, Stephen Church, Tim Bale. "The Impact of Proportional Representation on Government Effectiveness: The New Zealand Experience", Australian Journal of Public Administration, vol 62 no 4, December 2006, p. 7-22.
(Vowles Banducci Karp 2006) Jack Vowles, Susan A. Banducci, Jefferey A. Karp. "Forecasting and Evaluating the Consequences of Electoral Change in New Zealand", Acta Politica, vol 41, 2006, pp. 267-284. Available from NZES website:
http://www.nzes.org/exec/show/research#Articles