Why does anyone want to be a screenwriter? It is the most difficult job in the business. Facing a blinking cursor and a blank screen is much tougher than interpreting that screenplay. And for this arduous work, the screenwriter is compensated less than the producers, director, and stars: It is pretty rare for even an A-list writer to get any kind of big-money profit participation on a film, while it is de rigueur for those in the aforementioned categories. And, unlike the other artists who work on films — and in most other art forms — it is common and even pro forma to replace a screenwriter on a studio project. While book editors probably have given notes to e.e. cummings and Norman Mailer, I doubt anyone ever rewrote them. I can’t imagine that after Bruce Springsteen sent Columbia Records the songs for Born to Run, an executive said to him, “That’s great Boss, or, eh, The Boss, but we think it best to hand these over to John Fogerty and let him do a pass on them.” Dalí, Rodin, and Chopin would probably be aghast to learn of how motion picture scripts are developed. On a big-budget film, it is not uncommon for six or more writers to have worked on the screenplay, including the director and a friend of the star who is brought in just to work on his character’s dialogue. After 27 years working in this industry, I’ve heard many writers complain about unjust situations or how a movie could have been better had their work made it to the screen, but not about the actual experience of being rewritten or rewriting someone else. So in search of illumination on the topic, I decided to ask a group of four top script writers — David Koepp (Jurassic Park, Spider-Man), Brian Koppelman (Rounders, Ocean's Thirteen), Jeff Nathanson (Catch Me If You Can, The Terminal), and Andy Walker (Se7en, Sleepy Hollow) — for their thoughts on the curiously standard procedure of swapping writers on movies.