I think post modernism is useful in understanding Fight Club because it offers depth and meaning to the film. There are other critical approaches and topics such as the argument of crisis of masculinity or Freud's idea of the Id and the ego. Post modernism is the topic that i think is most applicable to this film.
The house on Paper Street is an example of intertextuality, which is post modern, because it has been copied from Psycho which copied the house from a painting by Edward Hopper. The inside of the house is copied from Hitchcock's Psycho, it is laid out similarly to the house in Psycho. This is a copy of a copy of a copy, which means that the same idea has been used and used multiple times. The house is meant to represent how society doesn't last, the house in the painting is painted nicely, and then when it is used in Psycho, the house becomes dirty and used and abused and then in Fight Club, the house is entirely ruined, an eye sore.
Fight Club is post modern because the characters make it known that it is a film. This is called surfacing, when Edward Norton faces the camera and talks to the audience while Brad Pitt edits a film reel at a cinema. The editing is done so that it looks as though it's been filmed on an old film reel, with shaky camera techniques and spots of light. Pitt and Norton both talk to the camera as if talking to audience when they're explaining what Pitt does at the cinema to make a living.
An example of irony is when the characters refer to Jesus and God. When Norton asks Marla to get on the coach and get away from the city, he stops the coach by stepping out in front of it and putting his arms out, standing like a crucifix. This is ironic because Norton's character is not God and he is not Jesus. This is an example of irony because within his community in Fight Club, Norton/Pitt is perceived as a Godlike figure, as the leader of the group.
Fight Club pays homage to Forest Gump, A Clockwork Orange and Psycho. Tyler shouts at some 'run, Forest, run!' and there are many references to A Clockwork Orange, for example, when Tyler goes to Marla's flat and stands next to a set of draws and knocks the phallus so that it wobbles. This is paying homage to films that have offered influence to Fight Club.
Fight Club is a hybrid film that mixes drama and action. This is an example of post modernism because hybrids are a relatively new genre of film.