[quote name='sendme']jaykrue, I have to say I'm looking at it the same as gokou36. The first John can not be the son of Kyle. I see it like this
First John is born by someone else
Sends Kyle back into the past
Kyle gets Sarah Conner pregnent
Sarah has John only this time he is the son of Kyle.
In the future John sends Kyle back because he knows that Kyle is his father and is the one that has to be sent back.
The first John has to be born in order to send Kyle back. Kyle can not go back unless John is born. So someone else has to be his father in the first time line of events.[/quote]
And again, I say, you're looking at things too linearly. As I've expressed time & time again, the nature of a predestination paradox is that it is naturally contradictory and circular - there's no beginning or end. There is no such thing as a 'beginning' kyle reese or a 'beginning' john. Even your example falls under that. Look at it carefully. Even if 'someone else' is the father of John, most likely he will be sent back in time to impregnate Sarah. According to predestination paradox, this person will most likely (but not necessarily) be named Kyle Reese since fate doesn't like itself to be thwarted. Sarah is fated to give birth to John Connor just as she is fated to be impregnated by someone from the future. The likelyhood of it being a person named Kyle is very high.
Were we to start discussing higher order physics then we can introduce other concepts such as string theory or multiple parallel time dimensions. Let's use your example. Say a different person is the father of John connor, all the events of T1-T3 happen. Call that Timeline 1. Now John sends back Kyle into 1984. But since he is affecting events here, Timeline 1 is no longer a possibility but still exists. You now have more than one timeline by virtue of a time traveler messing with things. One scenario is as laid out in Terminator 1 & Terminator 2 - Kyle impregnates Sarah only to die. Another is Kyle impregnates Sarah & lives. Now you have 3 timelines happening concurrently. Still another future is in which, Kyle dies but fails to impregnate Sarah and she is impregnated by someone else. That's 4 possible futures and so on and so forth. I won't go any further since the realm of possiblity is infinite. But the idea of multiple time dimensions is that anything you do at any point in time alters what dimension the time traveler exists but has no consequences for the previous timeline he came in. So, let's say the events of T1 & T2 happened as is and Skynet is effectively destroyed. That then means that all Kyle changed is a 'different' future & not his own timeline.
But how do you resolve such things? Well, there's an idea called
Novikov's self-consistency principle which basically asserts that if an event exists and that would give rise to a paradox, or to any "change" to the past whatsoever, then the probability of that event is zero. Meaning there is probably no chance that timeline 3 & 4 exist. That says that time is not multiple, like in the case above, but rather like a river. Any rocks (time events such as Kyle traveling to the past) in its path, the river will go around and reform on the other side resulting in the same events happening. In this case, Kyle is destined to go to the past and Sarah is destined to be impregnated by him and John is destined to send Kyle back to the past. No significant changes are allowed. Judgment Day and the events leading up to it can be delayed (probably for an indefinite period) but it will eventually happen.
EDIT:
[quote name='greydt']Nope. jaykrue explained it perfectly.
If you want to visualize it, draw a circle and put a line through it. The line is linear time, while the circle is Kyle.
In movie terms, I think you're thinking more of "Back to Future" type time travel which involves branching, and they avoid paradox at all cost.[/quote]
Damn, I wish I'd just said that.
