Prescience Is Predictable/Headscratchers

Wouldn't you be powerless no matter what?

 * Scenario 1 seems to be that you know the future and can do nothing about it if it's already been predicted. Scenario 2 seems to be that going against prediction is possible, but you already know if a) you'll try this, and b) you'll succeed. So if both of those things are already set in stone, wouldn't you end up with a situation where you were powerless to not stop whatever crisis has been predicted? In short, isn't your destiny already set either way?