"I'm sure there's a rational explanation for this."
— Velma
Basic Information
As far as the mundane world is concerned, every fortean event has some kind of rational (and probably very dull) explanation - UFOs are actually weather balloons, the invincible killer robot is actually a man on PCP wearing a ballistic vest and the vampires that attacked you were probably just a pack of crack-addled goths.
The bland, official explanation may or may not be at all convincing, but it will be official. All establishment sources will be expected to parrot it and anyone who dissents can expect to be treated as insane (at best) or a criminal (at worst).
Whether the mundane authorities actually believe their "official explanation" or not will depend on the setting (and the Weirdness Isolation Tropes at work within it) - and sometimes from power centre to power centre: whilst the mayor and the local cops will believe with every fibre of their being in a gang with vicious pet dogs loose in their town, The Agency may well be assembling a black-ops team with military grade weapons and silver bullets to clean up the werewolf problem.
Some settings have this as an actual phenomenon, a defence that the human brain actively deploys to protect itself from the damaging nature of a reality that contains things that don't make sense1.
Sources
Game and Story Use
- Useful when PC journalists, cops etc. get caught up in something nasty … and no-one believes them.
- Also useful as the PCs try to warn the town of imminent mass casualties.
- The tendency of this trope to lead to messenger-shooting can also be played upon when the PCs are ignored and the inevitable happens … who to blame? Obviously the dangerous fantasists warning of a zombie attack - there's no such thing as zombies so they must have killed all those people themselves to corroborate their delusions.
- Use this as an explanation as to why "the authorities" aren't doing anything about the problem and/or PC cops, soldiers etc. can't get reinforcements, extra supplies and what have you.
- "Flamethrowers? Why are 3rd Loamshire (Territorial) trying to draw flamethrowers? Best get the provost marshall to look into it - sounds like someone down there's gone a bit loopy".
- Game mechanics for this may be tricky.
- The self-censoring version can stretch suspension of disbelief for some people: folks in the real world are eager to believe in supernatural or irrational things on quite flimsy evidence as long as it's not directly called "magic." You can still make it work, though:
- All the real supernatural things are deeply unpleasant, and people don't want to remember or think about them; a fairy believer who sees real fairies is likely to walk away a committed skeptic, but possibly start carrying cold iron for reasons they can't explain.
- There's social pressure to believe in only the "right" kinds of supernatural things; manifestation is currently popular, Hermeticism less so. Someone who encounters a real magical working will keep quiet about it for fear of censure, and eventually fit it into the acceptable belief system.
- The "self-censoring" is something that was actually imposed on people: some kind of global magical effect or side effect of magic that forces people to rationalize away or forget specific events while still allowing them to believe in the supernatural in general.
- Arguably a large part of "madness" in the Cthulhu mythos is the loss of the ability to do this - to see the universe as it really is in that setting, is to become mad and basically unable to function normally as a regular human.