Ontological Inertia

Basic Information

Ontological Inertia is tendency of that which exists to continue existing.

In stories involving magic and the supernatural, it refers to whether or not a spell or condition continues to exist after the passing of it's creator. If killing a vampire returns the humanity to all the lesser vampires he's sired, then Vampirism can be said to lack Ontological Inertia. If a spell or curse survives it's caster's death, it can be said to have Ontological Inertia. In sci-fi and fantasy, this principle is sometimes applied to entire Empires: the death of Sauron or Palpatine results in a landslide victory by Minas Tirith or the Rebel Alliance. A lot of this will depend on how a given setting interprets the laws of magic.

In time travel stories, Ontological Inertia refers to the "force" or situation that makes it difficult or impossible for a time traveler to change history. It may occur as just a tendency for major events in history to continue on roughly the same path, or as a very potent and exact force that makes any alteration of the past impossible. It can manifest as bizarrely implausible coincidence, a more subtle thematic resonance, or even a disastrous energy release such as a Time Ripple (see also: Delayed Ripple Effect) or Marty McFly's hand dissolving while he's trying to play guitar. It may be that changing the past is a little challenging, exceedingly difficult, downright impossible, and/or highly dangerous.

Sources

Bibliography

1. TV Tropes Wiki on Ontological Inertia in regards to Time Travel

2. TV Tropes Wiki on the lack of Ontological Inertia

Game and Story Use

• Very powerful spells could be balanced by a lack of Ontological Inertia. Kill the caster, and the spell breaks.
  • When an ancient Wizard dies of old age, his greatest magics unravel, and the face of the world transforms.
  • Perhaps bring the final death to all those ancient Vampires and Liches isn't such a hot idea after all.
    • They might have used Magic to create the castle or dungeon you fought them in, which now comes crashing down around you (like in so many video games).
      • This may help to explain its unfeasible architecture - with the laws of physics suspended by magic, all sorts of other things can be suspended from structures that would otherwise not hold them. Likewise with the suspension of disbelief.
    • All their many victims might suddenly be returned to life, creating a population explosion and resultant food shortages.
• If the Gods created the world, will the world survive the death of a God?
• A villain could seek to collapse an Empire by desecrating the grave or relics of the first Emperor. This might or might not be a form of Sympathetic Magic.
• In a time travel campaign, the players might not start out knowing what degree of Ontological Inertia exists in the setting. They'd have to figure it out via trial and error, risking Temporal Paradox in the pursuit of knowledge.
• The existence of OI provides the cunning GM with lots of useful plot hooks - even once the villain is defeated, there are plenty of adventures to be had cleaning up the mess he left. Without it, you need a whole new campaign.
• Lack of OI can also reduce the level of grimdark in a setting - if all (or most) of the harm done by a given villain goes away with his death, the setting is far less grim … plus in puts a very direct kybosh on the old weasly line of "killing me won't bring her back" (or whatever). Realism, of course, will suffer proportionally.
• This may explain why the sealed-evil-in-a-can was sealed into a can rather than destroyed … destroying it might well inadvertently ruin something else. Of course, those who unseal it a thousand years later might not be aware of this…
• Combining the two types could be confusing but interesting. The spell not only breaks, but distorts the past to remove its effects. Some of them might remain as bizarre coincidences, but anything blatantly magical is removed.