I was just wondering if anyone could think of any reasonable reason as to why in Looper the loopers have to kill their older selfs? I mean why not just send the older looper back to a different looper to kill and nobody would be any the wiser? It seemed to cause them a lot of problems....
Shamelessly copied from my answer over on sci-fi & fantasy.SE:
In an interview with Slashfilm, the director, Rian Johnson, addresses this:
Why is it essential for a looper to close his own loop?
This is another one of those questions Johnson had answered in his head but didn’t put in the movie. In fact, he even conceived a scene with Abe addressing it but never shot it.
“People in the future, all they know about time travel is to be afraid of it. So they’re trying to keep it as tight as possible. So the initial reason they set it up this way was to keep the causality loop as tight as possible,” Johnson said. Because, for example, if someone else kills your older self and you have to exist with your own murderer for 30 years, what’s stopping you for murdering them or doing something to screw everything else up? ”Every bit of evidence is gone from that loop when you kill yourself,” he said.
This is a good example of how Looper's premise is shaky in terms of logistics -- too many unanswerable questions, such as:
Wouldn't it be better to have the FIRST person each looper kills be the looper's future self? Then each loop would be closed from the start.
Given their drug-addled, crime-ridden lifestyles, how many loopers will actually live a full 30 years after "retiring"?
If a given looper did live 30 years, wouldn't he go into hiding in year 30? Or maybe start cooperating with the authorities in an effort to save his life?
Overall, if they're all running around for 30 years, isn't there a risk that one or more loopers would alter the timeline significantly, changing what the world would look like in year 30?