Annoying Brother

I'm getting quite annoyed "talking" with my brother (I emphasize on the inverted commars as talking sounds like being lectured with him). He has been trying to undermine my personality and intelligence for the last half an hour making him sound like the one who's always right. He was lecturing me about how I talk and use sarcasm when he's the one who needs lessons on how he talks as he alienates people and makes other people feel and sound stupid. What frightens me is his general inability to trust anyone or thing to the point that I'm worried he's schizophrenic. I try to sympathise with him but sometimes he's just so annoying. He's also extremely clever at instigating an argument but most of the time he's making a mountain out of a molehill by developing on the argument with very shallow explanations or evidence. If his "explanation/evidence" fails he begins to go in protective mode and starts trying to undermine the other person's intelligence or by forgetting what the other person just said. But what makes him even more clever is he never seems to lose an argument. He knows when to stop an argument or start to add humour so that it stops, therefore neither side wins or loses. On other occasions he manages to make himself sound correct by using the "I said it so many times so it must be right" technique. I just don't need this at 2am when I'm trying to finish my homework!