Actually, the movies do have a coherent chronology, albeit not within the universe of the film itself as experienced by any of the characters other than Marty. The viewer can identify specific changes in the world line as they follow Marty from 1985 (at the Twin Pine Mall) to 1955 (Calvin Cline), back to 1985 (and the Lone Pine Mall and Biff the Auto Detailer), then forward to 2015 (where post-crash Hilldale Marty who cannot play the guitar and the Sports Almanac), then back to 1985 (Biff Tannen’s Pleasure Palace), thence back to 1955 (with Biff Sans Almanac), then to 1885 (with Marty as Clint Eastwood and the soon-to-be christened Clayton Ravine), and finally back to 1985 (with the renamed Eastwood Ravine). It is critical to note that every single change in timeline is precipitated by some direction action by Marty, e.g. pushing his father out of the street, convincing his George to ‘rescue’ Lorraine from him, buying the 1950-2000 sports almanac, challenging Mad Dog Tannen to a duel, et cetera. It is also worthy of note that no other character experiences changes in the timeline except in Marty’s presence (Doc doesn’t see that Lone Pine Mall 1985 has become Biff Tannen’s Pleasure Palace 1985, Jennifer notices that the fax in her pocket changes from “You’re fired,” to blank because she is next to Marty.)
What can we deduce from this?
It is clear that Marty is no casual pawn in this series of achronological events without volition or free will; he is the key decision making element in every major change of the timeline, the decider of fates, the Prime Observer of this universe. In fact, despite the many challenges and almost continuous threats to life, Marty barely gets a scratch (save for being hit by Lorraine’s father’s car and being dragged behind a horse). It is clear that this entire universe exists completely to serve Marty and keep him entertained or occupied, which also explains how Marty could introduce the music of Chuck Berry to 1955 without Berry having previously played in the Twin Pines Mall 1985 timeline. So, this is clearly a solipsistic universe built around Marty’s consciousness, and the when Marty goes from one timeline to another, the other characters not in his presence just cease to exist. (This also explains why both Marty’s father and girlfriend change radically in appearance between movies with nobody, including Marty, expressing any surprise despite the fact that the change occurs without Marty changing timeframes or doing anything that would inherently change the past.)
It will be left as an exercise to the reader to determine whether Marty is trapped in a Rekall simulation gone awry, is actually a member of a pandimensonal species capable of bending space and time to their wills, or is actually a figment of Tommy Westphall Universe as a previously unsuspected branch off of the Family Ties/Spin City trunk.
Stranger