vanilla sky was defintily a question of reality or dream. very similar to discussing the readings Descartes seems to be trying to re-evaluate what he at one point thought to be true and existing. By doubting that he really exists he realizes that in order for someone to be deceiving him he has to exist. The question then becomes since he is real then what around him is real still. The arch deceiver that he talks about cannot manipulate his mind unless it exists right?