On Nov 27, 2008, at 11:47 AM, Kristofer Munsterhjelm wrote:
Jonathan Lundell wrote:
It's a reason that "(in)sincere" isn't very good terminology for
everyday use; likewise "manipulation". They're fine terms when well-
defined and used in the context of social choice theory, but they
carry a lot of baggage. A voter is, in my view, completely
justified in ignoring the name of the election method ("approval",
for instance) and the instructions (vote in order of preference)
and casting their vote strictly on the basis of how the ballot will
be counted.
(Which is why I'm partial to ordinal systems; it seems to me that I
as a voter can pretty easily order candidates without considering
strategy, whereas the decision of where to draw the line for
Approval, or how to assign cardinal values to candidates,
explicitly brings strategy into the picture.)
For ordinal systems, it's pretty easy to consider what a honest
ballot would be, assuming a transitive individual preference. "If A
is better than B, A should be higher ranked than B". It's not so
obvious for cardinal systems. What do the points in a cardinal
system mean? We can get some measure of a honest ballot by
transporting an ordinal ballot into a cardinal ballot: if you prefer
A to B, A should have a higher score than B. But other than that,
what can we do? This seems to be a problem of cardinal systems in
general, not just a particular implementation like Range (or
Approval, if you consider Approval Range-1).
Thinking further, it would seem that cardinal systems can solve it
in two ways. Either the points are in reference to something
external ("how much would I like that X wins in comparison to that
nothing changes from status quo"), or it refers to a subjectively
defined unit ("how much do I 'like' X" for an individual definition
of "like"). I think ratings, as commonly (and intuitively) used, are
of the second part, but that leads to problems with the aggregation
of the points. If one voter likes many things and another likes only
a few, how do you compare the two preferences? Ranking gets around
that since it only asks about relative information (though one could
argue there's a very weak form of this problem with equal-ranking;
how different does your opinion have to be of two candidates before
you no longer equal-rank them?).
I don't really see a need for equal-ranking in a single-winner
election. As a voter, I'm answering the question "if you were
dictator, of this set of candidates, who would you choose?". I don't
really need the option of naming two candidates to the same office; if
I really have no preference between them, I can flip a coin, or choose
the tallest, or ugliest, or whatever.
I guess what I'm trying to say is that the problem of discerning a
honest vote from a strategic (optimizing) one seems to be inherent
to all cardinal methods, because we can't read voters' minds. That
is, unless the external comparison can be made part of the ballot
itself.
I suggest that the problem is worse than that: that the voters can't
even read their own minds, in this sense. Suppose that I would have
ranked Edwards > Obama > Clinton in the recent US primaries. Fine, I
can make Edwards=100, but I really don't have the foggiest idea what
it would mean to make Obama=75 as opposed to Obama=50. Do I like
Edwards "twice as much" as Obama? What can that possibly mean? It
seems to me that range voting (including approval) immediately reduces
to a purely strategic exercise. And what I'd prefer to do is to
eliminate (to the extent possible) the motivation to strategize at all.
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