Are you trying to characterize good decisions, or cases in which good decision making took place, or good decision making processes, or good things to do if you are participating in decision making? From your bullet items, it appears that you mean the latter.
But what reason do you have for thinking that having everyone adhere to these practices would lead to good decisions? Are you really interested in good decisions, or rather do you merely wish everyone involved to have a good time and feel good about themselves later?
You mention an evolutionary process to improve your initial list of good practices. How would you know whether this process is going in the right direction? What exactly is the objective here?
Do you really think that the problem in collective decision making is to get the participants to reason well? Isn't it also necessary that they listen to learn each others interests as well as each others arguments? That they somehow first come to a consensus as to what balance of interests should be sought before they try to determine rationally how best to achieve those ends?
Downvoted. I thought you did better the first time when I couldn't quite see what your point was.
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.)