I'm not sure it's important that my conclusions be "interesting". The point was that we needed a guideline (or set thereof), and as far as I know this need has not been previously met.
Once we agree on a set of guidelines, then I can go on to show examples of rational moral decisions -- or possibly not, in which case I update my understanding of reality.
Re ethical vs. other kinds: I'm inclined to agree. I was answering an argument that there is no such thing as a rational moral decision. Jack drew this distinction, not me. Yes, I took way too long coming around to the conclusion that there is no distinction, and I left too much of the detritus of my thinking process lying around in the final essay...
...but on the other hand, it seemed perhaps a little necessary to show a bit of my work, since I was basically coming around to saying "no, you're wrong".
If what you're saying is that there should have been no point of contention, then I agree with that too.
"How can a terminal value be rational?": As far as this argument goes, I assert no such thing. I'm not clear on how that question is important for supporting the point I was trying to make in that argument, much less this one.
I have another argument for the idea that it's not rational to argue on the basis of a terminal value which is not at least partly shared by your audience -- and that if your audience is potentially "all humanity", then your terminal value should probably be something approaching "the common good of all humanity". But that's not a part of this argument.
I could write a post on that too, but I think I need to establish the validity of this point (i.e. how to spot the loonie) first, because that point (rationality of terminal values) builds on this one.
Query: by what objective criteria do we determine whether a political decision is rational?
I propose that the key elements -- necessary but not sufficient -- are (where "you" refers collectively to everyone involved in the decisionmaking process):
If an argument satisfies all of these requirements, it is at least provisionally rational. If it fails any one of them, then it's not rational and needs to be corrected or discarded.
This is not a circular definition (defining "rationality" by referring to "reasonable" things, where "reasonable" depends on people being "rational"); it is more like a recursive algorithm, where large ambiguous problems are split up into smaller and smaller sub-problems until we get to a size where the ambiguity is negligible.
This is not one great moral principle; it is more like a self-modifying working process (subject to rational criticism and therefore improvable over time -- optimization by successive approximation). It is an attempt to apply the processes of science (or at least the same reasoning which arrived at those processes) to political discourse.
So... can we agree on this?
This is a hugely, vastly, mindbogglingly trimmed-down version of what I originally posted. All comments prior to 2010-08-26 20:52 (EDT) refer to that version, which I have reposted here for comparison purposes and for the morbidly curious. (It got voted down to negative 6. Twice.)