Maybe they could only send back a certain number of years, just like in the TV show 7 days. Maybe they could only send back 14 years, or how ever many years it was.

How about this for a twist:
Maybe John Connor only learned how to defeat the Terminators because the Terminators were sent back to kill and this taught him how to defeat all the other Terminators in the future.

He sure knows alot more than others because of the Tx's.

We have different futures. Once the 1st T was defeated the future had been changed. Then the T2 was defeated and the future was changed again. Now T3 changes everything again.

It sounds funny, I know,
But it really is so,
Oh, I'm my own grandpa.

I'm my own grandpa.
I'm my own grandpa.
It sounds funny, I know,
But it really is so,
Oh, I'm my own grandpa.

Now many, many years ago, when I was twenty-three,
I was married to a widow who was pretty as could be.
This widow had a grown-up daughter who had hair of red.
My father fell in love with her, and soon they, too, were wed.

This made my dad my son-in-law and changed my very life,
My daughter was my mother, cause she was my father's wife.
To complicate the matter, even though it brought me joy,
I soon became the father of a bouncing baby boy.

My little baby then became a brother-in-law to Dad,
And so became my uncle, though it made me very sad.
For if he was my uncle, then that also made him brother
Of the widow's grown-up daughter, who, of course, was my stepmother.

Father's wife then had a son who kept him on the run,
And he became my grandchild, for he was my daughter's son.
My wife is now my mother's mother, and it makes me blue,
Because, although she is my wife, she's my grandmother, too.

Now if my wife is my grandmother, then I'm her grandchild,
And everytime I think of it, it nearly drives me wild,
For now I have become the strangest case you ever saw
As husband of my grandmother, I am my own grandpa!

I'm my own grandpa.
I'm my own grandpa.
It sounds funny, I know, but it really is so,
Oh, I'm my own grandpa.

OK, I know it's been over a month since this post, but this cracked me up. I'm wondering how Save Ferris can judge how "accurate" a time-travel plot can be, without actually having experienced time travel. It's totally speculative...how can one approach be any more or less "accurate"?

wow.... you people are thinking way too much over an action film!

If John Connor can't be born unless he sends his father back in time, and later they successfully defeat Skynet from being created and thus saving the world, John will have no reason to send Reese back in time in the first place.

Actually, I think the paradox can be answered in the deleted scenes of Terminator 1. In those scenes, Sarah makes a decision to go and attack Cyberdyne to change the future (ala T2) But the rub is this, by attempting to destroy Cyberdyne (and hence Skynet) she is really the mother of both John Conner and Cyberdyne - because it is possible that Cyberdyne would have never created Skynet without the chips. (Basically a single universe theory - not a multiple universe theory)

As it stands in T1 now, the fact that the T1 ends at Cyberdyne seems like chance..which it was not in the original thinking of the movie's logic.