The random component represents the idea that even the best debaters will run into an argument that just doesn't go their way. If it was always an instant win just by having X charisma, that would get boring quickly.

Originally Posted by DragonCommander
or just choose whatever he chose last

I think this theory started back in beta with an observation from Stabbey, but it just isn't true. Many times this "strategy" has bitten me in the rear. For all intents and purposes, it's random.