[EM] attempt of a grand compromise

[James Green-Armytage]

Dear Jobst and Steve,
	Please allow me to join your conversation.

Jobst, you wrote:
>As to TRUNCATION RESISTANCE, I fear the proposal might FAIL that because
>of the specific definition of defeat strength. With defeat strength =
>winning votes, this criterion also follows from immunity, but with
>defeat strength defined otherwise, it will probably fail. It seems this
>will be a general problem with cardinal weighted pairwise -like methods,
>do you agree? If so, we should figure this out more clearly since it may
>undermine our hopes that cardinal weighted pairwise will have better
>strategy properties...

	Woah there, let's not get too upset. First of all, yes, under the current
definition of the cardinal pairwise method, it is possible to change the
result from a sincere CW to another candidate via truncation. This is not
possible in winning votes, and it is possible in margins. 
	In some intermediate versions of my cardinal pairwise proposal, I had a
majority/minority beat provision, which stated that any pairwise defeat
where the winning side constitutes a majority of the valid vote was
automatically stronger than a pairwise defeat where the winning side does
not constitute a majority of the valid vote. If you add this provision,
then cardinal pairwise meets the truncation resistance criteria. (The
provision itslef was designed for this purpose.) So, if you think that the
criteria are really important in itself, you can just add that provision.
	However, I haven't included that provision in the most recent versions of
my proposal, because I currently consider it to be awkward and
unnecessary. Basically, the truncation resistance criteria say that you
shouldn't be able to pull off a successful burying strategy just by
truncating your ballot, or insincerely ranking two candidates as being
equal -- instead, if you want to bury someone, you have to actually
reverse at least one preference ordering. I recognize the usefulness of
these criteria, and I consider them to be a valid point in favor of
winning votes against margins, but I don't think that their importance
should be overstated. That is, they don't mean that strategizing voters
will have less of an ability to bury a candidate, they just means that
they need to use reversal rather than truncation to do so. I submit that
if voters are determined to strategize, the need to use order-reversal
won't be much of a barrier.
	I submit that in cardinal pairwise, those who are likely to truncate
against a candidate will generally fall into the high-incentive,
low-ability category of strategic voters which I define in my proposal
(section 6b). That is, when C>A>B voters are willing to truncate to bury A
in order to help C, i.e. to vote C>A=B, it is likely that the difference
between candidates A and C will be large, the average C>A and A>C rating
differentials will be large, and the A>C defeat, assuming one exists, will
be difficult to overrule in cardinal pairwise, making the truncation
strategy unlikely to be effective.
	To sum up, cardinal pairwise's anti-strategic properties apply to both
strategic truncation and strategic order-reversal. Winning votes makes
strategic truncation ineffective, but those who want to strategize can
easily get around that by using order-reversal instead.

my best,
James