[EM] Range strategy pathological example (was Re: IRV vs Plurality)

[Jameson Quinn]

> Two weaknesses, it seems to me, and I'm less sanguine about their
> fixability.
>

Depends what you mean, of course. But I stand by my "one fixable weakness".


>
> One is, as you suggest, the strategy problem. Range, and it's limit in one
> direction, approval, require the voter to make cast a strategic vote; there
> really isn't any such thing as a non-strategic range or approval ballot. But
> voters are privy to different amounts of variably useful information about
> other voters' preferences, and other voters' strategic choices in view of
> those (perceived) preferences, and so on ad infinitum.
>

Yes. There are two ways to fix this. One is to do something to "idiot-proof"
the ballots - allow only near-top or near-bottom votes, or encourage middle
votes only for lesser-known candidates. This essentially make Range into
almost Approval, without losing too much expressivity (and thus no one is
forced to vote unstrategically simply to gain expressivity). As you say,
there's still strategy, but I think voters could handle it.

The other way is to try to have the system handle the strategy for the
voters. There are several possibilities - I've proposed "Score DSV", another
possibility is to do a hybrid Bucklin system with IRV-like sequential
"elimination" (actually, non-elimination vote spreading). You may say that
these systems are no longer truly range-like (they do satisfy the Condorcet
criterion, and they are not trivially precinct-summable, so you'd have a
point), but they do still encourage range-like or approval-like voting.


> The second problem kicks in with the suggestion that there *is* a sincere
> range ballot (not that any voter would cast it), namely some objective
> measure of utility, comparable from voter to voter. The idea that there's
> some objective (or at least intersubjective) common measure of cardinal
> utility is, deservedly, a fringe idea—at best—in social choice theory.
>
>
It doesn't have to be objective or intersubjective (or cardinal, for that
matter). It just has to be subjectively interval-scaled, or decently close
to interval-scaled. Which may not be exactly true, but is IMO certainly
close enough to truth to run with. So I don't think this is an
insurmountable problem at all.

Jameson Quinn
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