What memories did "Old Marty" have in 2015 of his time travel adventures?

Question

In Back to the Future II, young Jennifer from 1985 sees Marty McFly and his family in 2015, observing that Marty and Jennifer are married & their son is a slacker, watching various future technology at work, and finally seeing Marty cooperate with Needles in some shady scheme (because he can't stand being called "chicken"), after which he is promptly fired by his boss. All of this seems to depict a Marty who gained nothing from his various time travel adventures, which raises the question:

• What did that Marty, age 47 or so, remember in 2015 about his time travelling adventures?
• Do those memories end at the point in Back to the Future I where Marty has returned to 1985 (i.e. without Doc Brown's sudden appearance & summons to head into the future)?
• Does he remember any/some/all/none of his journey to 2015 as a 17-year-old?
• Does he remember not just that trip but also the trip to the Old West of Back to the Future III (which presumably changes the future from what Jennifer is observing)?
• Does he remember avoiding the car crash at the end of Back to the Future III? (If so, why does Needles' taunt of "chicken?" affect him?)

His parents seem to have benefitted from the results of his first trip to 1958 (i.e. confident & happy, as shown at the end of Back to the Future I -- just older), and the older Biff character as seen in 2015 also seems to reflect the changes from those adventures as well (his outlook seems more that of a retired auto detailer, rather than having retired as George McFly's supervisor).

So some 2015 characters in Back to the Future II show the effects of Marty's first changes to the space-time continuum, but the Marty-of-2015 shows none of the resourcefulness and bravery of the 17-year-old hero. Granted, this is after his crash with the Rolls Royce and subsequent disappointments, so maybe that explains why he is the way he is.

Nevertheless, I'm curious: how much does that Marty (age 47, in 2015) remember of his adventures in a hot-wired DeLorean sailing through space & time at 88 mph?

Answer 1

I think it's clear that Marty only remembers the events of Back to the Future 1, minus the part at the end where Doc comes back to collect him.

Keep in mind Doc went to the future first, and then came back. I think this is key to understanding the problem. If you look at it from his perspective, he went into a future in which Marty never travelled into the future, because Marty only did that as a result of him coming back to collect him and change his kids' lives.

That was a change, and the only one which could have affected future-Marty's memories.

As we're forced to assume from the whole Biff-returns-the-DeLorean-after-stealing-the-Almanac issue, it takes a sort of 'meta-time' for a change to "catch up", and so when Marty traveled to the future with Doc, it didn't have time to change to match whatever new stuff he learned (and it's quite possible that the majority of his trip wouldn't have changed his life dramatically, only the discovery of exactly what it was that got it on the wrong course... before that, he might have started to remember his kids were in danger, but also remember coming to save them from the past, and so be fairly chill about the whole thing).

You could also convincingly argue that for his whole trip into the future, the future timeline COULDN'T stabilize with a change because anything he learned would change his memories which would change the future which would change what he learned, so on in an endless loop until one stable predestination paradox emerged... failing that, it had to wait until he came back in order to push the change forward into the new future (which we never actually see, just the last remnant of it in the fading fax machine after he finally avoids the accident). This all leaves aside the uncertainty thanks to Biff finding out about time travel and using it to alter the past while they were in the future.