I also think that the example isn’t perfect (although I haven’t formalized why yet). But, you’re describing tactical voting, which is considered one of the “downsides” of RCV.
You’re already being tactical when you decide that Carol isn’t a threat and (falsely) uprank her. What changes if you go a step further to decide that she is a threat?
In fact, I think that the standard formalism for defining “tactical voting” is in terms of submitting a vote that doesn’t faitfully reflect your true preferences. Under that formalism, falsely upranking Carol is tactical, but switching back to your true preferences because of what you expect others to do actually isn’t tactical.
… and it’s odd to talk about tactical voting as a “downside” of one system or another, since there’s a theorem that says tactical voting opportunities will exist in any voting system choosing between more than two alternatives: https://en.wikipedia.org/wiki/Gibbard–Satterthwaite_theorem . At best you can argue about which system has the worst case of the disease.
And, if you’re comparing the two, plurality has a pretty bad case of tactical vulnerability, probably worse than IRV/RCV. That’s why people want to change it: because tactical voting under plurality entrenches two-party systems.
I also think that the example isn’t perfect (although I haven’t formalized why yet). But, you’re describing tactical voting, which is considered one of the “downsides” of RCV.
You’re already being tactical when you decide that Carol isn’t a threat and (falsely) uprank her. What changes if you go a step further to decide that she is a threat?
In fact, I think that the standard formalism for defining “tactical voting” is in terms of submitting a vote that doesn’t faitfully reflect your true preferences. Under that formalism, falsely upranking Carol is tactical, but switching back to your true preferences because of what you expect others to do actually isn’t tactical.
… and it’s odd to talk about tactical voting as a “downside” of one system or another, since there’s a theorem that says tactical voting opportunities will exist in any voting system choosing between more than two alternatives: https://en.wikipedia.org/wiki/Gibbard–Satterthwaite_theorem . At best you can argue about which system has the worst case of the disease.
And, if you’re comparing the two, plurality has a pretty bad case of tactical vulnerability, probably worse than IRV/RCV. That’s why people want to change it: because tactical voting under plurality entrenches two-party systems.