We accept the reality of the world with which we're presented.
That awkwardly formulated line of dialogue could have come from "The Matrix". In fact, the world in which Truman Burbank lives could be considered a Matrix For One. The world is fake, but he's the only one who believes it's real. The whole world has been created for his benefit, and he's lived in it since the day he was born. That's a whole lot of world for one man. This is a film I can never get tired of, however often I watch it.