[EM] Doesn't matter what preference means, Markus

[MIKE OSSIPOFF]

Markus said:

That's quite irrelevant since I use the term "IIAC" in the same manner
in which they use the term "Regularity" and since I have never claimed
that there is a relation between my use of the term "IIAC" and their
use of the term "IIAC".


I reply:

But that's just it: You don't.

It doesn't matter whether P&P used "preference" to mean "preference",
as I took it to mean, or whether they used "preference" to mean
"voted candidate ordering that doesn't change", as you took it
to mean.

What does matter is that they said: "Given the profile of personal
preferences...", and you didn't say that or anything like it, or
anything that relates to how people vote.

Not only did you not say that, but when I asked you if you assumed
anything about how people vote, you never admitted that you did.

Obviously an assumption that people vote in accordance with their
preferences, or that their candidate orderings don't change, is
an assumption about how people vote. You never agreed to making such
an assumption.

Therefore you're mistaken: You weren't using "IIAC" in the same
manner that P&P use "Regularity".

Maybe you are now, though, if you've changed your IIAC definition
now that I've showed you that your old one doesn't act as you
thought it did, and that it isn't Regularity.

If the future, when you say "IIAC", do you mean your old IIAC
definition, or do you mean Regularity exactly as P&P define it?

What if it turns out that P&P assume that ballots exactly reflect
sincere preferences? Would your IIAC still be their Regularity, or
would you still define your IIAC by stipulating that everyone's
voted candidate orderings don't change, rather than talking about
actual preferences? It could make a difference, depending on how P&P
define sincere voting, how they specify in what way ballot orderings
should match preferences.

So, when you say "IIAC" in the future, which of those ways will you
mean it?

Markus continued:

You will have to rephrase this because I have absolutely no idea what
you mean. There are no "unstated assumptions" in the IIAC definition.
Due to Pattanaik and Peleg, the input of a "decision scheme" is
a set of linear orders. Where this set comes from, whether this set is
sincere or insincere, whether the voters have understood this decision
scheme and act in a rational manner, all these questions are of
no importance. Your claim that there is an "unspoken assumption"
(1) that "people vote in accordance with their preferences" or
(2) that "there's some relation between a voter's preferences and
his ballot" is not justifiable.

I reply:

Fine. As I said, that doesn't matter. It can be taken up later.
For now, what matters is that they said "Given the profile of
individual preferences, and you didn't say that, and, further,
you never admitted to any assumption about how people vote.
You can call voted candidate orderings preferences if you want to,
but you never said that you assume that those voted orderings don't
change when we add new candidates. Your IIAC is not Regularity, unless
, based on my help, you've now changed your definition.

Markus quotes Blake:

Blake wrote to Mike (28 Jan 2002):
>Having said all that, I'll get to how I interpret P&P. P&P talk about
>ballots, and criteria and methods based on those ballots. By ballots I
>could just as easily say preference orders. I don't think P&P intend to

I reply:

You could just as well say egg-salad sandwiches too. But when
we say "I prefer chocolate to vanilla, we mean that I like chocolate
better than vanilla. That's what preference means. If you want to
call ballots preferences, than that must be stated, because that
isn't what preference means, unless you say that that's what you're


If P&P, when saying "preferences" meant "voted preferences", then
they have left out an important word. It isn't reasonable to expect
us to guess that they mean voted orderings when they say preferences.

But this issue isn't relevant to the matter of whether Markus's
original IIAC is Regularity. It isn't, no matter how we interpret
P&P's "preferences".
going to use it to mean.


>propose a theory in which the preference orders are mental states, but
>the method works on actual ballots, so the ballots must be "sincere",
>whatever that might mean.

I reply:

"Whatever that might mean" would be whatever P&P defined it to mean,
if they had defined it. Maybe, as Blake says, P&P are calling ballots
"preferences". As I said, that's really sloppy unless they say
that they're going to give preference that new meaning.


They ignore the sincerity issue. They just
>have methods and criteria that refer to preference orders. But where
>those preference orders come from isn't their concern.

I reply:

If they're talking about the candidate-orderings that are available
to the count, then they're talking about ballots, unless the count
is done by a psychic or that oracle that some here like to refer to
sometimes.

Thank you Blake for clarifying that they mean "ballot" when they
say "preferences". It's sloppy, but at least we now know what they
mean. Again, that doesn't affect the matter of whether Markus's
original IIAC is Regularity. It isn't, because it says nothing
about preferences, whatever preference means, or ballots or
how people vote.

Blake continued:

For you,
>preference order implies sincere preferences, and you recognize that a
>real-world method can only work on cast votes. But for P&P, a method is
>just a function from a hypothetical set of preference orders to a set of
>winners.

Ok, thanks for clarifying that. If an oracle knew the preferences,
or if sincere or insincere preferences were recorded on a ballot,
either of those would do for what P&P mean by preferences. I just
meant that P&P should have been a lot clearer about that.

But, Markus, your original IIAC still isn't Regularity.

Mike Ossipoff


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