What you’re proposing is closely related to Michel Balinski’s system of Fair Majority Voting. Both systems get proportional representation while having a representative from every district and without any sort of at-large seats. I think your system can be thought of as a greedy approximation of Balinski’s, like how Sequential Proportional Approval Voting is a greedy approximation of Proportional Approval Voting. Fair Majority Voting should elect slightly better winners, but your algorithm is a lot easier to describe.
Warren Smith has criticized Fair Majority Voting while proposing something similar (which he also finds very problematic). Smith’s main objection is that it’s easy for tactical voters to unseat prominent MPs in what he calls “targetted killing”:
With Balinski, the NaziLoon party (which gets 1% of the votes and hence deserves 1% of the seats) necessarily will enjoy a multiplicative scale-up factor of about 50, as compared with the Mainstream party (which gets 50% of the votes) with a multiplier of about 1. In other words, Balinski is going to force each NaziLoon vote to count about the same as 50 Mainstream votes.
This is a huge “leverage” or “amplification” factor subject to easy exploitation via “strategic voting.” For example, suppose for the purposes of argument that Justin Trudeau (leader of Canada’s Liberal party, recently elected prime minister in 2015) is the most popular MP in Canada. So the Tories might like it considerably if Trudeau’s district were to un-elect him and thus remove him from power. Tory leadership can easily accomplish that goal. They simply tell the Tories in Trudeau’s district “we suggest that instead of voting Tory, which is a lost cause, you vote NaziLoon.” The 50× amplification factor then easily carries the day, and – voila – Trudeau is gone.
I call this “targeted killing.” Now the Tories might now want to try that again, selecting as their target some other important Liberal MP. If, however, they kept re-using the NaziLoon party as their pawn in the targeted-killing game, it would no longer work as well. So instead, for their next “target” the Tories would switch to using the BeerLovers party as the (new) pawn. And so on.
This would cause all the important leaders in Canada to be “assassinated” – removed from political power – and instead a ragtag random collection of normally unelectable NaziLoons, BeerLovers, etc would be all over parliament. So perhaps the best two-word description of the situation that would be caused if Balinski’s voting system were the design for Canada, would be “complete devastation.”
Your system also looks vulnerable to this—if tactical voters cause the NaziLoon party to get 5% of the vote in Trudeau’s district (compared to 1% nationwide) this would yield a relative vote share of 5, which should easily be enough to oust Trudeau. I think Smith overestimates the severity of this problem since it would be possible to enact a rule like “You don’t actually need to get elected in order to be the prime minister so long as you got at least 40% of the vote in your district”, but this is still a relevant consideration when there are other MPs that people want to remove. For example, if 10% of the electorate in each district was bigoted against a particular minority they could use this strategy to keep that minority out of parliament.
It makes sense to me that you’d describe my proposal as easier than Fair Majority Voting—I understand the former, but not the latter!
As for “targeted killing”, I think a threshold of, say, 5% of the nationwide vote prevents that. The Tories cannot tell their voters in Trudeau’s riding to vote for the NaziLoons, because the NaziLoon vote is discarded as it doesn’t reach 5% nationwide (hopefully!). So those Tories have wasted their vote and Trudeau still gets elected. Do you think that makes sense?
I think the 5% threshold makes “targetted killing” a lot less viable, but it doesn’t eliminate the possibility altogether. It may still be possible to use a slightly-more-mainstream party in such a way; if a party gets 5% of the vote nationwide but 15% in Trudeau’s district, that’s still a relative vote share of 3, which should be far more than Trudeau achieves. Still, I think the combination of a threshold with a “you don’t actually need to be electing to Parliament to hold a leadership position” rule should be sufficient to reduce the “targetted killed” problem to a tolerable level at least.
The more I think about it though, the more I lean towards something closer to MMP over the 100% single-winner districts approaches. If a party’s best showing in any one district is under 15%, I think it makes the most sense for that party to only have at-large seats; the remaining 85% of that district’s voters will really feel like they drew the short straw otherwise. (Also, I imagine the possibility of losing one’s seat to a third-party candidate with far less support within one’s district would cause a lot of incumbents to oppose such a system.) Still, I think there is considerable middle ground between MMP and your system that allows for having substantially fewer at-large seats (as a fraction of all seats) than you get in Germany or New Zealand, and this middle group could easily be better than MMP.
I confess that I don’t understand the detailed working of Fair Majority Voting either; it’s clear enough in the two-party case, but I’d have to study it in a lot more detail to learn how the algorithm works in general.
Another solution that might be more palatable than allowing someone who just lost their own district to become PM is to normalize having PMs from either of the Houses of Parliament. I’m not sure how Canada elects its senators, but if you make that as province-wide PR then party leaders can be decently assured to get a Senate seat. (Actually, I checked and Senators are appointed by the Governor-General on the advice of the Prime Minister; constitutional convention might make for the leaders of any parties represented in the Commons to be guaranteed a Senate seat).
What you’re proposing is closely related to Michel Balinski’s system of Fair Majority Voting. Both systems get proportional representation while having a representative from every district and without any sort of at-large seats. I think your system can be thought of as a greedy approximation of Balinski’s, like how Sequential Proportional Approval Voting is a greedy approximation of Proportional Approval Voting. Fair Majority Voting should elect slightly better winners, but your algorithm is a lot easier to describe.
Warren Smith has criticized Fair Majority Voting while proposing something similar (which he also finds very problematic). Smith’s main objection is that it’s easy for tactical voters to unseat prominent MPs in what he calls “targetted killing”:
Your system also looks vulnerable to this—if tactical voters cause the NaziLoon party to get 5% of the vote in Trudeau’s district (compared to 1% nationwide) this would yield a relative vote share of 5, which should easily be enough to oust Trudeau. I think Smith overestimates the severity of this problem since it would be possible to enact a rule like “You don’t actually need to get elected in order to be the prime minister so long as you got at least 40% of the vote in your district”, but this is still a relevant consideration when there are other MPs that people want to remove. For example, if 10% of the electorate in each district was bigoted against a particular minority they could use this strategy to keep that minority out of parliament.
It makes sense to me that you’d describe my proposal as easier than Fair Majority Voting—I understand the former, but not the latter!
As for “targeted killing”, I think a threshold of, say, 5% of the nationwide vote prevents that. The Tories cannot tell their voters in Trudeau’s riding to vote for the NaziLoons, because the NaziLoon vote is discarded as it doesn’t reach 5% nationwide (hopefully!). So those Tories have wasted their vote and Trudeau still gets elected. Do you think that makes sense?
I think the 5% threshold makes “targetted killing” a lot less viable, but it doesn’t eliminate the possibility altogether. It may still be possible to use a slightly-more-mainstream party in such a way; if a party gets 5% of the vote nationwide but 15% in Trudeau’s district, that’s still a relative vote share of 3, which should be far more than Trudeau achieves. Still, I think the combination of a threshold with a “you don’t actually need to be electing to Parliament to hold a leadership position” rule should be sufficient to reduce the “targetted killed” problem to a tolerable level at least.
The more I think about it though, the more I lean towards something closer to MMP over the 100% single-winner districts approaches. If a party’s best showing in any one district is under 15%, I think it makes the most sense for that party to only have at-large seats; the remaining 85% of that district’s voters will really feel like they drew the short straw otherwise. (Also, I imagine the possibility of losing one’s seat to a third-party candidate with far less support within one’s district would cause a lot of incumbents to oppose such a system.) Still, I think there is considerable middle ground between MMP and your system that allows for having substantially fewer at-large seats (as a fraction of all seats) than you get in Germany or New Zealand, and this middle group could easily be better than MMP.
I confess that I don’t understand the detailed working of Fair Majority Voting either; it’s clear enough in the two-party case, but I’d have to study it in a lot more detail to learn how the algorithm works in general.
Another solution that might be more palatable than allowing someone who just lost their own district to become PM is to normalize having PMs from either of the Houses of Parliament. I’m not sure how Canada elects its senators, but if you make that as province-wide PR then party leaders can be decently assured to get a Senate seat. (Actually, I checked and Senators are appointed by the Governor-General on the advice of the Prime Minister; constitutional convention might make for the leaders of any parties represented in the Commons to be guaranteed a Senate seat).