the error the pseudo-left makes with proportional representation is that it doesn't understand the strength of it's opponents.
to be clear: hard leftists, like myself, don't even really believe in parliaments at all. i mean, if you want my actual answer on this it's that we shouldn't have elected representatives in the first place, we should be operating via direct democracy. every parliamentary vote should be converted into a referendum. and, with the technology in front of us, direct democracy is more possible than it's been at any point since the polis. so, i can change my ranked ballot, if you include direct democracy.
1. direct democracy
2. preferential voting (with a single elected representative in a riding system)
3. first past the past
4. proportional representation
the way your average pr advocate thinks is really trying to advance a tactic that's an end-around majority rule. they start with the understanding that they can't actually win an election, and then scheme up this idea to legislate themselves greater influence than they're able to get at the box, in the existing system. then, they think they can convince people to give them the power they can't get in the status quo, and then they wonder why it doesn't work.
but, it's being driven essentially by self-interest - they think it's the best way to advance their own interests. they don't tend to think about what happens when you open the spectrum to the forces of the right, or maybe they think they can defeat them in debate, or maybe they think they're not really a problem.
israel is the prime example. as insane as netanyahu comes off to even moderate conservatives in the west, in israel he is on the left of his coalition. what proportional representation has done in israel is allow for ultra-orthodox and ultra-right parties to take control of government by holding the center-right coalition hostage. instead of building coalitions in the centre, likud needs to constantly pander to the extreme right in order to hold power. so, that's what they do. conversely, while the arabs can elect a few members of parliament, they're perpetually kept out of any kind of coalition; rather than give arab israelis a voice, the system functions to completely exclude them from the process by siphoning them off into their own block. and, i really wish that more enlightened observers would kind of clue in and recognize that so many of the problems in israel are a consequence of the way they elect representatives to parliament.
in italy, it's a different problem, namely instability. they spend so much time jockeying over power, that they don't have time to actually govern.
and, in germany you're seeing the same kind of problems develop that have essentially destroyed israel.
i could go on...
is this a real issue in canada? well, i want to take you back to the short-lived minority government of joe clark. clark's win itself is an example of how bizarre our system in canada is. clark didn't just lose the popular vote, he lost it by four points. it wasn't even close. but, the liberal vote was too concentrated in too few places (because the ndp ate into it in just the right way to split it), and the conservatives eked out a small plurality of seats.
the results were as follows:
1) conservatives. 36% (+0.5%), 136 seats. joe clark.
2) liberals. 40% (-3%), 114 seats. pierre trudeau.
3) ndp. 18% (+3%), 26 seats. ed broadbent.
4) social credit (-0.5%). 5%, 6 seats. fabien roy.
so, you see what happened.
clark needed 142 votes to pass a budget, and he wasn't going to get it from the liberals or the ndp. he needed all six of the social credit votes to govern.
social credit was an odd party, and what was left of it by 1979-1980 had morphed entirely away from it's initial roots as a christian socialist party. the socreds governed the west of canada for decades in the middle of the last century, and were known for doing all kinds of horrible things. by 1980, they had been reduced to a small number of seats in quebec, and were essentially an extreme right party, known for perpetuating anti-semitic conspiracy theories about jewish bankers running the world.
so, clark is left in a hard position: in order to govern, he needed the support of what was widely seen as a neo-nazi party. and, he refused to do it.
the socreds provided a list of demands to clark, which he was to meet in exchange for support. clark refused those demands, triggering an election. trudeau won his last majority, and the socreds were wiped out - a frustrating result for the conservative movement, but a positive outcome for the country overall.
years later, stephen harper would resurrect some socred economic ideas in his list of boutique tax credits and monthly child care checks, but the party was largely abandoned as an impediment to stopping the liberals.
what would have happened in a pr system?
if strict pr, the parliament would have looked like this:
1) liberals. 113.5 seats. so, 114.
2) conservatives. 101.5 seats. so, 102.
3) ndp. 50.6 seats. so, 51 seats.
4) socreds. 13 seats.
5) rhinoceros party. 2 seats.
there would have been one more seat to distribute to an "independent", but it's not clear what that means.
the rhinoceros party was a parody party, and would no doubt not have actually sat. rather, there would have been a coalition between the liberals & ndp, which was the status quo throughout the 70s.
but, we would have ended up with twice as many nazis in parliament, and they would have been given official party status, including votes on committee. the ndp, on the other hand, would not gain anything they didn't already have, which was the balance of power through most of the 70s. and, in past years, the socreds polled much higher than 5%, too.
if you look at recent elections, you see a spattering of parties on the left and a single party on the right, but this is recent in canada. there was a western conservative party through the 80s and 90s called the reform party, as well as a more recent hard-right party from the same area called the wildrose party. conservatives know that they have to unite to win a fptp system. that would probably not be true in a pr system, which would allow the right of the party to split into it's own block, which could then govern in coalition with a centrist conservative party. this is a recipe for the same disaster that's happened in israel, where centrist conservatives become reliant on the far right to form a coalition. fptp has the opposite force in motion - the centre-right has to constantly try and shut the hard right down in order to appeal to moderate voters. harper was bad enough; we don't want to create a voting system that permanently embeds a reform or socred style hard-right into the parliament, and then forces the conservatives to rely on them to pass budgets.
but, the average pr advocate doesn't even think of that; they only think of their own self-interest.
a proper survey of how this works, which was not done by the committee that studied this, would realize the perils of this kind of system, for this reason - advocates think it amplifies the left, but the evidence in front of us suggests it actually amplifies the right.
what is better about preferential voting?
well, it maintains the riding system, which i think has some benefits to it, but ensures that the candidate actually gets to 50%. it's not ideal from anybody's perspective, and i don't think anybody argues that it is. political scientists and mathematicians will claim it fails a key test (which i acknowledge but think is arbitrary). socialists will argue that it maintains a competitive concept in elections, rather than promote a collaborative one, and that's a valid critique, although it can be blunted using other means. conservatives will argue that you're rigging the field, because they know they'll lose a lot of seats. and, there's a general fear (that i think is overstated) that it will lead to perpetual centrist government, which may in some sense be true but opens up a question - where is the actual centre in this country?
what it is is a compromise, which is also very canadian. it maintains the basic structure of the status quo, while tweaking it to prevent vote splitting from creating false majorities over weak pluralities.
if you're to ask me what the problem is, what's broken, what needs to be fixed, it's people winning seats with 30% of the vote. that's crazy; that shouldn't be. so, it fixes that, and that's really what i'm out to actually do.
but, if you want to talk about direct democracy instead then that's even better...