The Uncertainty Principle
Now the solution wich I think is pretty unbreakable by anything the players do (or not do), is called the (Niobaras) Uncertainty Principle. And yes, it is obviously based on (Heisenbergs) Uncertainty Principle. It is not my invention, I am merely translating it from another RPG source.
The principle says:
- The more precise the prophecy, the less precise reality
- The less precise the prophecy, the more precise reality
Like you can not measure the position of a quantum without affecting it's direction (and thus can never know both to any precision), the act of making a prophecy or otherwise acting on it changes the direction of reality. The terminology is a perfect match.
All you need to do, is tell your players those rules apply for the setting. Now no mater how it turns out - nothing happens, they stop it way to early, it comes to pass anyway - you are in the clear. The prophecy was not nessarily broken/or wrong.
Case: Self Fullfilling prophecy
"A man often meets his destiny on the very road he took to avoid it."
This is a case of imprecise Prophecy. The propehcy is that "X would happen". A precise prophecy would have been "X will happen if you try to avoid X". But if you had gotten such a precise Prophecy, you would never have tried to avoid X and thus never gotten to X. So reality would have been inprecise.
Case: It happens anyway
Apparently the prophecy was not precise enough for the heroes to prevent it. So reality turned out precisely as predicted.
Example: Nothing happens
Say it was prophesized that "Demons that feast on the minds of mortals will rule for a thousand years." but it does not come to pass. There are several ways this could have been:
- the prophet was plain wrong. It happens to the best of them.
- His prophecy was so precise, it derailed reality. Maybe the person that would have summoned the first of those demons heard of it and decided not to go that particular way? Maybe somebody else heard of it and choose to stop that potential summoner? Maybe 3rd parties that deal with threats to the status quo knew to look out of those demons, cutting their unfolding world domination plan short, without ever making it public?
Case: The pointless prophecy
This is a case seemingly outside the rules. Examples:
- "You are going to have a heart attack, after I am done telling you that you are going to have a heart attack". Most beings would react with stress to such a message. Wich might just trigger a heart attack.
- "Attempts to look into the future do not work [in this setting]. The attempt to look into the future with a Artifact Crystall ball let so much arcane energy flow into it, that it exploded. Wich it realibly predicted!"
You can leave that as a 3rd option. "Propehcies must be made in time". But it could also just be a case of the prophecy being inprecise. Inprecise in the sense that it was to late for you to do anything about it.
Prophecies are a bit like realtime programming: If you do not get the answer (prophecy) on time, it is not usefull to have it at all.
Example: Inprecise Consequences
I remmeber one from "Chip 'n Dale: Rescue Rangers" Season 2, Episode 22 "Seer No Evil". The propehcy of death was that Chip would be crushed by a "elephants trunk".
This is a good example for many reasons:
- this had elements of a Self-fullfilling prophecy as only attempts to avoid it resulting in him being at exactly the right place, at exactly the right time.
- trunk meant "a large box with a hinged lid for storing or transporting clothes and other articles." rather then "the elongated, prehensile nose of an elephant." (It was a carnival. Stuff like that could happen).
- While he was exactly under it when it hit the ground, there was a hole he dodged into. The fortune teller did not see that part (as it went to black)
- But maybe it was also precise enough? At start, Chip did not beleive in prophecy. But then others started to come true until he himself was doubtfull. Maybe that bit of extra attention and those slight changes in how the story progressed made it so he was at the right place to avoid it?