My world is this:

  1. Magic exists
  2. Magic is invoked by stating logical proofs
  3. If you can prove something, it becomes true
  4. A stronger proof over-rules a weaker one

In a traditional magic system, to cast a shield you would probably wave a magic stick about and scream a bit or whatever. Here - instead - magic's just logic. So for a fairly weak shield, you could invoke Descartes:

Cogito, ergo sum. I think, therefore I am.

Shout that and anyone else trying to disprove your continued existence wouldn't be able to. That is, unless they come up with an even better proof :)

If it wasn't obvious, the whole system's meant to be a bit tongue in cheek. Does anyone know of any "spells" that would work in this world (with a focus on combat, but anything stands)?

  • 3
    $\begingroup$ What philosophy school are you willing to use? Also, questions that are just pooling for ideas are often put on hold as too broad. Could you rewrite it in a way that will make it possible to objectively decide which answer is better? $\endgroup$
    – Mołot
    Feb 22 '17 at 8:55
  • $\begingroup$ Any school would be fine. $\endgroup$
    – Fraser
    Feb 22 '17 at 9:01
  • $\begingroup$ As a student in logic, I love the idea. The thing is, you jump from the concept of proof to what I'd like to call social philosophy. Could you give us an example of spellcasting/combat? $\endgroup$
    – PatJ
    Feb 22 '17 at 10:08
  • $\begingroup$ I think solipsism is a major flaw in your story, If you think you can be aware of your own existence but how can you be so sure about others? What if reality is just a very persistent dream or if we are in solipsist matrix in which everybody else is created by an AI Machine? $\endgroup$
    – user31264
    Feb 22 '17 at 10:46
  • 1
    $\begingroup$ The more I think about this the more I want to play with it. does the universe accept all forms of logic? Dependence logic/Categorical logic/Attributional calculus or just one? Does it accept math proofs? is it possible to slip a flawed proof past the universe until someone finds the flaw in the proof and points it out to the universe? $\endgroup$
    – Murphy
    Feb 22 '17 at 11:04

BRB, since written statements work I'm off to use the Banach–Tarski paradox written on a sphere to turn it into into a self replicator.


The effect should be something like this.

By the time anyone figures out what's happening there should be thousands of them that they need to hunt down and disprove.

If I'm really mean I also write some extra malicious proofs on them so they start negating existence or suppressing rational thought in the area around them.


To defend my home I'm going to use the Zeno defense

Zeno's shield.

I ring the area with 2 circles...

Anyone who wants to get past the second must first move half the distance between the 2 points and then half the distance between their current location and the second line....


Truth vs Reality

This is interesting, because Truth and Reality are not the same thing. And the mind-bender that you have created here is that you create Reality from Truth.

An interresting article on the subject: Top 10 Difference Between Truth And Reality. Summary of the list:

  1. Truth is absolute, Reality is cognitive.
  2. Truth hurts, Reality bites.
  3. Truth is singular, Reality is manifold.
  4. Truth is objective, Reality is subjective.
  5. Truth is permanent, Reality is ephemeral.
  6. Truth emancipates, Reality constrains.
  7. Truth redeems, Reality informs.
  8. Truth comes from the heart, Reality follows from the head.
  9. Truth requires courage, Reality reflects convenience.
  10. Truth is always real, Reality is not always true.

The real problem you are facing as an author is that you may confuse your readers. While philosophers and logicians may find this very interesting, the question is if this applies to all your readers.

Also note that some roleplaying game system have touched upon this, so maybe you can see about that for inspiration. Like the spell "disbelief" that lets you alter reality simply by disbelieving the inconvenient parts of it. The Somebody Else's Problem Field from The Hitch Hiker's Guide To The Galaxy is another such "spell", this time sarcastically reflecting upon people's ability to completely ignore things that they feel are "somebody else's problem". So whoever wants to make things invisible or not noticeable, simply attaches an SEP field to these things. :)


So maybe rather a physics magic? You know, your logic magic would need to be aware of faux logic and semantic problems. Because what would be the easiest flaw in your magic is language.

Second problem - escalation. You could cast a shield spell based on logic "steel plate can deflect bullet" so your opponent cast armour piercing bullets can" so, if you are quick enough, can cast "double steel armour plate with ceramics inside" and so on.

So after 5 fights in this world the only fights are made "chess-style" two people thinking if they can outsmart the opponent and if they can they shake hands and call one of them victorious.

Because you know, it's the only logical way,


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