In Meditation One, Descartes presents the idea that perhaps he is being manipulated by God to perceive the world in a certain way, saying,
“there is a God… by whom I have been made to be as I am.” God’s parallel in The Truman Show is the show’s creator and director, Christof. He manipulates Truman to be the way Christof wants him to be. He dictates who he is friends with, who he marries, where he works, even the weather (asyndeton). And through “killing” Truman’s father by drowning him during a boating trip in a storm, he instills in Truman a long standing fear of water. This effectively insures that he is unable to leave Seahaven, as it is an island. Even through subtle events such as continuously proclaiming the merits of small towns and calling Seahaven “small town of the year” in the newspaper, Christof even manipulates Truman’s feelings about his hometown, hoping to prevent him from leaving. Nearly everything, from his life experiences to his likes and dislikes, has been engineered by Christof so that Truman becomes an unwitting actor in The Truman Show. Truman has been marketed as the only real person on the show, but not even that can be trusted after Christof’s extensive influence.
However, one difference is that Truman can definitively prove that his reality was artificially created. He is able to prove that he was living in a TV show, and that most of the things he has accepted as true are not. Descartes cannot. He cannot prove that his life is a simulation or the work of a demon or the work of God. He is instead left knowing only that his consciousness is real.