Originally posted by: Rebel Scumb

You mean when Vader and the Emperor were talking about bringing in young Skywalker, they both knew that he would have to kill one of them? That does not track.

Well according to Lucas thats the idea. Each being evil knows the other cannot be trusted, but they also need each other in the mean time. Each is banking on the fact that they will come out on top, and trying use the other's desire to do the same to their advantage.

or at the very least you could say that Vader does not know, but I don't think thats nessesary. Vader assumes he can get luke to kill the emperor, the emperor assumes he can get Luke to kill vader

That still sounds more like a principle than a rule. If it were a rule which all Jedi know, then Vader and the Emperor know that "turning young Skywalker" is all bad news for someone in their relationship. If it were a rule and Vader wanted to turn Skywalker, he wouldn't announce it to the Emperor.

The way GL puts it sounds more like a general, pridictable way the Sith behave, but not a rule. A rule leaves no room for Vader to be fooled, no room for the Emperor and Vader to conspire to turn Skywalker while secretly plotting to use Skywalker against each other. But if it's more like a tendency -- an aspect of evil which comes from being power-mad, well that's just not a "Rule of 2" . That name, "Rule of 2" has to be shorthand for behavior that isn't really in stone. Otherwise, it just doesn't track.

With that being the case-- Palpatine can certainly bend this "rule" as the most powerful Sith ever. He can plan to revive a mechanical Darth Maul in the person of Grievous as an "extra" apprentice. He's planning on losing Dukoo anyway-- and Grievous as well. Yet he could use both their help in the meantime. He is, after all, orchestrating the destruction of all Jedi.