Slaughterhouse-Five: Flashbacks 1 key example

The literal and figurative flashbacks, and flash-forwards, are integral to Vonnegut's style and can be understood as symbolic of the post-traumatic stress disorder (PTSD) that often plagues soldiers returning from war. This element of the story is counterintuitively represented not through the discussion of the war, but through the alien abduction of Billy Pilgrim. On Tralfamadore, Pilgrim lives a new life, exposed to an alternative culture while entirely without freedom. Eventually, he is forced to return to his old life on Earth. The dichotomy between life in the war and life at home, between this alien world and Earth, is in many ways the focus of the novel. The recurring flashbacks further this dichotomy and evoke PTSD in the process. Pilgrim's alien abduction is then a broader metaphor for the experience of a soldier.

Some scholars argue that the novel as a whole can be interpreted as a soldier suffering from PTSD, with the science fiction elements a byproduct of mental illness or a consequence of the traumatic plane crash. This interpretation is far from agreed-upon, but it is nevertheless an important potential interpretation of the story and one that is supported by the presence and frequency of flashbacks.

PTSD notwithstanding, the flashbacks contribute to Pilgrim's outlook on life: having seen the past and the future time and time again, he does not believe in free will and appears apathetic when faced with "new" experiences. The reader can easily understand this perspective after reading the story themselves and being forced to see the world through Pilgrim's eyes.