[EM] Meta-criteria 3 of 9: Value: expressiveness

[Jameson Quinn]

Expressiveness considers voting as being a communicative act. How, then,
should it be structured so the society's members best understand each
others' preferences? Probably the most expressive ballot would be an
unlimited, norm-referenced Range ballot - you could express any level of
preference, with some presumably universal reference - "each point is a
dollar", or "10 points of difference represents something you would die to
acheive". However, unless you actually collect a Clarke tax, such a system
would be overwhelmed by strategic effects. That's true even if you're not
even dealing with an election, with practical effects on results, but just
some kind of poll, whose entire purpose was for expression. By exaggerating
my vote, I can effectively supress the expressive power of other voters.

However, in more traditional systems, there are generally few or no
strategies to supress others' expressivity, if expressivity is the only
goal. Consider Range voting: if, on a simple nonbinding poll, I
"strategically exaggerate" to an approval-style response, that can't really
be called a dishonest response, as I am simply making a choice to express
only the most important distinction I see. Only when the vote is an
election, not a poll, does dishonesty come into the picture, as utility
conflicts with expressivity.

Thus, dishonest/strategic voting presents two separate problems. It may or
may not reduce the overall utility of a voting system's result. (In fact, in
some cases it may improve the result.) But, by weighting outcome over
expressivity, it cannot help but reduce the effective expressivity of a
system. This leads to a certain paradox: systems which seek to increase
expressiveness by increasing voter freedom - for instance, Range as compared
to a Condorcet system - could increase strategic opportunities, and thus in
the end reduce expressiveness - for instance, if Range were to end up as
pure Approval in practice.

In my conclusion (email 9 of this series), I'll come back to this paradox,
and attempt to start resolving it.
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