Sophie Amundsen
The protagonist of the novel, Sophie is approaching her 15th birthday when she receives the first of the letters from Alberto in the mail. She is lonely and curious about the world around her. As the novel goes on, it becomes more clear that Sophie is a fictional character created by Albert Knag, another character in the book. Despite this, Sophie becomes an increasingly complex and thoughtful character, who truly thinks about her thinking in the way that only a philosopher would.
Hilde Moller Knag
The other protagonist of the novel, Hilde is also approaching her 15th birthday when she is given the first part of Sophie’s story by her father, Albert. She is very similar to Sophie, in her loneliness and in her curiosity, but also in her rebelliousness - whereas Sophie rebels by writing on her English essay that Philosophy is more important, Hilde manipulates her father’s movements to retaliate on him for doing the same to his characters, Sophie and Alberto. The novel is just as much about Hilde learning philosophy and coming of age as it is about Sophie doing the same.
Alberto Knox
“The Philosopher” who is Sophie’s friend and teacher throughout the novel. Alberto is extremely smart and educated, and he symbolizes a magician who continually leads his pupil, Sophie, through tricks of life - encouraging her to always ask the most important philosophical question “Why?” He holds all of his own opinions in until the end of his tenure as teacher, when he reveals that he does not hold stock in modern mysticism. He teaches Sophie so well that when it comes time for them to escape Albert’s book, it is she who has to encourage him, saying that philosophers never give up, never stop asking questions, and never stop thinking.
Albert Knag
Albert loves his daughter Hilde, though he is not often home to see her. He works at the UN, but even as he is working there, he continues to send Hilde Sophie’s World, hoping to teach Hilde about philosophy. The similarities between Sophie and Hilde suggest that Albert is a good, caring father who knows about who his daughter is.
Helene Amundsen
Helene is Sophie’s mother, but she is very different in character. She is a kind woman and mother, but she is boring, bored and uninterested with her life because she does not ask philosophical questions. Sophie does accuse her mom of adultery, though she cares for her very much. Their relationship is not quite as poor as the relationship between Hilde and her own mother.
Sophie's Father
The novel says almost nothing about him, except that he is often abroad working as the captain of an oil tanker out at sea. He does not really exist in the larger novel, in fact, he barely exists even to Sophie in her own story.
Hilde's Mother
Hilde’s Mother and Hilde have a tenuous relationship- Hilde seems to get on much better with her father, Albert. Though the text never explains it, the reasons that Hilde and her mother are not close could be because Hilde’s Mother is uninterested in philosophy, like Sophie’s mother, or it could be because, like Sophie’s mother, Hilde’s Mother has committed adultery. Since this shows up in the text only in Sophie’s family and not directly in Hilde’s, that is unclear. It is even more unclear why it was ever mentioned. Is Albert pushing Hilde and her mother apart by sharing details of his own suspicions that his wife is an adulterer, through the veiled story of Sophie and her mother?
