Back to the Future 3

[Sonikku]

Eh why does Doc do anything. He spends all of 3 going on and on about how the time machine has to be destroyed and how it causes nothing but harm. Then he turns around and makes another one.

 

[Patranus]

And if Doc got

Spoiler

the letter

in #1 and

Spoiler

wore a bullet proof vest

, why would he have allowed the entire chain of events to happen to

Spoiler

send Marty back in time

And if Doc can

Spoiler

send a letter to Marty in 1955

in #3, why didn't he

Spoiler

send the letter to Marty BEFORE he was zapped by lightning.

 

[sactoking]

Why didn't he just go back to 1884 and leave some gas cans lying around for him to use? At some point he has the time machine train that can go anywhere.

Wasn't one of the tricks in going back to 1955 the second time that BTTF2 versions of Doc and Marty couldn't let the BTTF versions of themselves know they existed? If that was a critical element (which Doc made it sound like it was) then the end-BTTF3 Doc and Marty couldn't leave the beginning-BTTF3 Doc and Marty a bunch of gas or their (beginning-BTTF3 Doc and Marty) heads would assplode or something.

 

[sactoking]

And if Doc got

Spoiler

the letter

in #1 and

Spoiler

wore a bullet proof vest

, why would he have allowed the entire chain of events to happen to

Spoiler

send Marty back in time

And if Doc can

Spoiler

send a letter to Marty in 1955

in #3, why didn't he

Spoiler

send the letter to Marty BEFORE he was zapped by lightning.

It's temporal continuity, like I was referencing in my prior post. If Doc sent the letter to Marty before the lightning then Marty would try to stop Doc from getting hit which would mean Doc never went back and never sent the letter, and boom, time paradox.

Plus, they had just seen in BTTF2 what happens when a small change is made by Biff's old self and youg self.