Gaffer Tape said:

Moral relativism entered Star Wars in The Empire Strikes Back, and it's been there ever since. Yes, the original Star Wars was very black and white, but as soon as you reveal that the hero's father was a good Jedi who became evil, and that it's possible for him to be good again, you have moral relativism.

I disagree sir.

Anakin had once been good, but as Vader he was pretty non-relativistically evil. There was never any exploration as to how Vader saw himself, justified his actions, nor redeeming qualities of Vader presented.

In ROTJ he chose to die doing a good deed, but his 'evilness' was never in question until that moment. That's a changing character, but the good/evil dichotomy is still fairly cut and dry.