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Your zesty link detracts from the conversation. The zesty link makes a simplifying assumption, that under first past the post (called Plurality) voters vote for
by alan-crowe 8y ago
Your zesty link detracts from the conversation. The zesty link makes a simplifying assumption, that under first past the post (called Plurality) voters vote for the nearest candidate according to some distance.
For example, if 40% believe in A and 60% believe in B, and there one candidate, X, standing on platform A, and two candidates, Y and Z, standing on minor variants of platform B, the votes split 30% for Y, 30% for Z, and X gets elected with 40%.
It is easy to see how the 2016 presidential election would have worked out if this assumption was realistic. Hillary 52%, Donald(Republican) 24%, Never-Trump(Republican) 24%. Hillary wins by a landslide, despite playing a sub-optimal electoral college game.
The assumption is very far from realistic. I next turn to whether the lack of realism matters.
Imagine a three way race, with two old established parties, A and B, and a new third party, C. Under first past the post voters who prefer C > B > A, vote B, to avoid letting A in. Meanwhile voters who prefer C > A > B vote A to avoid letting B in. Under first past the post (FPTP) it is very hard to start a new party.
We might frame the issue this way: who decides the fate of the third party candidate? Under FPTP the third party candidate loses and this decision was taken long ago, by men now dead, when they opted for FPTP. Under IRV the fate of the third party depends on today's voters. If they are voting C > B > A and C > A > B then the third party candidate stages an upset victory. If they are voting B > A > C and A > B > C then the third party candidate is humiliated and doesn't bother running again.
The argument for IRV over FPTP is that we prefer that the fate of the third party candidate be in the hands of the voters, rather than seeing the third party candidate lose automatically, by the game theory of FPTP.
The zesty link simplifies away the problem that IRV is intended to solve. But it doesn't argue that the problem is small; it cannot do that because every-one can see that the spoiler effect under FPTP is a big issue. Instead it refuses to mention the problem, simplifies it away, and hopes that nobody notices. That is derailing, not contributing.