A good example of the absolute impo

A good example of the absolute importance of birth as a reference point for possible-world thinking—the inability for a narrative to posit such worlds without a starting point—is the popular 1983 movie Back to the Future. In this film, young Marty (Michael J. Fox) unwittingly travels into the past and finds himself inadvertently disrupting the romance between his future mother (Lea Thompson) and father (Crispin Glover). As the two drift further and further apart, the likelihood of their marriage and consequently of Marty’s eventual birth grows dimmer. Glancing at a picture of his family, Marty sees himself and his siblings gradually fading from the picture as he races to undo this damage and sidestep this version of the grandfather paradox.