And you thought weblogs were about trivial things, where you could hit a link and understand it all!
OK, you didn't. But I have. This is somewhat like the opposite: how to work at understanding your reasoning (both moral and logical).
The best you can do, even with your own behavior, is to try to piece together hypotheses about the hidden motives at work based on what the person actually does, situated in the context of things you know are generally true of why people might want to do those things.
Which leads precisely to that problem I highlight in the prior post: if we applied to ourselves the standards we use to judge others, would we like ourselves very much?