To be honest, your wrong. If you watch the movie with comentary Edward Norton admits that his characters name is Jack. There is also the hint of "i am Jack's colon".
Yes, Ed Norton does indeed refer to the character as Jack. This is taken from IMDb Trivia:
'Much confusion exists amongst fans about the Narrator's name. Many believe it is Jack due to his use of the phrase "I am Jack's...", but others argue that he only uses the moniker Jack because that was the one he saw in "Annotated Reader". Interestingly, in the press packages released for the movie, which came in the form of an Ikea-esque catalog, the character is referred to as Jack, as he is on the back of the DVD, and in the booklet accompanying the DVD, where the Chapter list is referred to as "Jack's Chapters". Also, the original screenplay by Jim Uhls refers to him as Jack. On the other hand, in the closed captions for the film, he is referred to as Rupert. Edward Norton reveals that he refers to the character as Jack on the audio commentary on the DVD and Blu-ray.'
The character also goes nameless in the book.
Sorry to spam up your comments, but I think all avenues must be considered :)
'Much confusion exists amongst fans about the Narrator's name. Many believe it is Jack due to his use of the phrase "I am Jack's...", but others argue that he only uses the moniker Jack because that was the one he saw in "Annotated Reader". Interestingly, in the press packages released for the movie, which came in the form of an Ikea-esque catalog, the character is referred to as Jack, as he is on the back of the DVD, and in the booklet accompanying the DVD, where the Chapter list is referred to as "Jack's Chapters". Also, the original screenplay by Jim Uhls refers to him as Jack. On the other hand, in the closed captions for the film, he is referred to as Rupert. Edward Norton reveals that he refers to the character as Jack on the audio commentary on the DVD and Blu-ray.'
The character also goes nameless in the book.
Sorry to spam up your comments, but I think all avenues must be considered :)