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At one point in the movie, Peter Van Houten ( Willem Dafoe ) talks to Hazel about the Trolley Problem. The Trolley Problem is a mental exercise in ethics presented by Philippa Foot in 1967. It poses a situation involving a runaway trolley that is bearing down on a group of five incapacitated people lying on one set of tracks. In contrast, a single incapacitated person lies on a parallel track. You can pull a lever and switch the trolley to the parallel track. You are then faced with the dilemma of doing nothing, in which case five people will die, or pulling the lever, in which case one person will die. However, Van Houten might have been referring to the most apparent meaning of this exercise; he might have been referring to its deeper meaning instead, which is not about sacrificing someone else but having the moral courage to sacrifice oneself and to be willing to suffer the consequences by confronting the problem at all. The focus of the Trolley Problem is not on the victims but on the person confronted with the situation.
The title is a variation on a quote from Act I, Scene II of William Shakespeare's Julius Caesar: Cassius says "The fault, dear Brutus, is not in our stars, but in ourselves..."
Author John Green based the character Hazel on a young girl named Esther Earl who was diagnosed with thyroid cancer. Green met her during a Harry Potter convention in 2009 noticing her carrying an oxygen tank. He came to like her because of some of the videos she put up on YouTube as well as her humor and openness. From the time they met to her death at the age of 16 in 2010, Green and Earl would exchange correspondence.
A replica of the interiors of the Anne Frank house had to be built as the movie was denied permission to film inside the actual house.
Green added via Twitter about Shailene Woodley's audition for the role of Hazel, "There were so many amazing auditions for the role of
Hazel, but Shailene's love for the book and
her understanding of Hazel blew me
away."
John Green: the father of the blonde girl talking to Shailene Woodley's character at the airport before the departure to Amsterdam.