"If you are against me, you're my enemy!" - Darth Vader
"Only a Sith deals in absolutes" - Obi-Wan Kenobi
Episode III
I recently got to thinking about this line as I wondered to myself what it truly meant.
When I look up the word absolute in the Webster's Dictionary, it states among other things:
1. free from imperfection or mixture;
2. free from control, restriction, or qualification
There are other definitions of the word as well which relate to absolute zero (complete absence of heat) and relating to fundamental units of length, mass and time, but I won't go into those here. I only wanted to try and justify, in my mind, the use of the word "absolute" by Obi-Wan in this instance.
Now, in Obi-Wan's case he was referring to the fact that Vader just said something that has very little flexibility. To be only one thing or another limits the possibilities of thinking on a broader scale. And that is how the Jedi viewed themselves ... as catalysts of the Force who think of all aspects of it and how they can broker peace through expanded thinking and awareness. Obi-Wan certainly opened himself up to a greater view of the Force when he killed Darth Maul ... he touched on his anger and his sense of revenge to do what he had to.
But in Vader's case, he was saying that Anakin had lost that sense of flexibility and was now on the path of the Sith, as Obi-Wan viewed it. He interpreted Vader's words as being free from the broader sense of Jedi thinking, and into a narrow view of one way or another. In that sense, what he said is true in that being with Vader or being his enemy is free from imperfection or mixture, as Webster's describes it. If a person chooses to be only with Vader and the Empire there is no mixing about with anything else ... that is his choice.
And the same can be said with definition #2. Vader was free from control and restriction by this point. He had the full support of his Sith Master who had control of the Republic (ironic?), and felt he could do exactly as he pleased. He could therefore make a statement like "if you're not with me then you're my enemy". He knew, through his arrogance, that his power could carry him to greater things and he would be the one in charge of his destiny and decide who would be with him or not.
And the Jedi, of course, had many controls and restrictions in place. The Jedi Code restricted its followers from a great many things that the Order felt would tarnish a Jedi or cause conflict within itself. It established rules that had good meaning behind them, but were not followed by each Jedi strictly, namely Anakin, which eventually were a cause in the fall of the Jedi.
So I don't think Obi-Wan was off base when you look at the word "absolute" and the meaning he put behind it. Vader was ruled by one line of thinking and that was demonstrated thoughout the saga ... he really did make it known that you were with him or his enemy, as evidenced in many scenes as both Anakin and Vader.
It's just too bad Obi-Wan didn't see it coming. Absolutely.