The TOS episode "The City on the Edge of Forever" is often considered as one of the best - if not the single best - Star Trek episode. However, I find a crucial element of the episode not convincing and am wondering whether it is simply a contradiction that should not be there.
Throughout the episode, it is quite clearly suggested that Edith Keeler was "supposed" to die before World War II -- i.e., that she would die before WWII if no one from the 23rd century did intervene -- and that McCoy saved her, which lead to a disaster in WWII. Therefore, Kirk and Spock had to prevent him from doing so. But what actually happens then is that the car accident that kills Edith Keeler apparently only happens because of the presence of Kirk, Spock, and McCoy (Keeler crosses the street again only because she sees them). Therefore, without the presence of anyone from the 23rd century, she would probably not have died in that accident. This apparently contradicts what had been suggested throughout the previous course of the episode.
Is there any convincing solution that is in line with the story of the episode?
Throughout the episode, it is quite clearly suggested that Edith Keeler was "supposed" to die before World War II -- i.e., that she would die before WWII if no one from the 23rd century did intervene -- and that McCoy saved her, which lead to a disaster in WWII. Therefore, Kirk and Spock had to prevent him from doing so. But what actually happens then is that the car accident that kills Edith Keeler apparently only happens because of the presence of Kirk, Spock, and McCoy (Keeler crosses the street again only because she sees them). Therefore, without the presence of anyone from the 23rd century, she would probably not have died in that accident. This apparently contradicts what had been suggested throughout the previous course of the episode.
Is there any convincing solution that is in line with the story of the episode?