Using the pre-cogs, they could see the future murders. There were a few problems though. If people knew that they were going to kill someone before they knew for real, then they could choose an alternate route, just as John (Tom Cruise) did. He knew he'd kill that guy, but he didn't, because he chose not to. It'd be like fate. If you know what you're going to do, you could change it so that you don't do that. Or, like fortune telling.. they tell you what's going to happen, and sub-consciously you make that happen.. then you think they are a hero, when they aren't, it's all your mind doing stuff for them.
Anyways, at the end, the dude is going to kill John (tom), and Tom makes him aware that they know he's going to kill him, and let's him know that he has a choice. He chooses to kill himself instead, thus proving, that when people know their future, they can change it.
There was a whole different part of the plot too.. about one of the pre-cogs having her mother killed... Basically, Steven Spielberg wanted to show that a system like that would never be perfect, even if we had "pre-cogs". There is always room for human error to occur. No one can trust anyone. There's always room for human fault.
The moral behind the movie was good, and Spielberg did a good job of projecting the drawbacks of the invasion of privacy, and giving government organizations too much power, which is already happening with this post-911 freak show. Too much power in the hands of few is bad, very bad... Even if it is someone that we are supposed to trust, like the FBI...
Speaking of the FBI, I live in Calgary, Alberta, which is the closest major city to Banff, Alberta, where they are holding the G8 this week. We've got loads of military here.. I saw the secret service today in their identical line of cars.. We have choppers flying around all day, and there are surface->air missiles everyone mile from here to banff. There's like 10 big army jeeps like 100 yards from our church
. Our poor little springbank airport (springbank is a rural area outside of calgary that I live in) is really crowded . It's sorta cool... Makes me want to be in secret service, or the military.
