Re: 12 Monkeys pilot greenlit by Syfy
I think what this boils down to is that Cole believes, because he's been led to believe, that changing the past is impossible. Whether the scientists believe it's impossible is difficult to say since we know they're not entirely honest, and their "science isn't an exact science."
The evidence we see during the film seems to me to suggest that the scientists are right and that the past can't be changed. That doesn't rule it out of course, but given the nature of the film itself did any of us really expect sunshine and lollipops at the end? Even if the only thing Cole ultimately did was clue in the scientists (perhaps a bit inadvertently) as to who spread the disease, that's still a sort of heroism.
It was the best of Trek, it was the worst of Trek...
"If I lean over, I leave myself open to wedgies, wet willies, or even the dreaded Rear Admiral!"