A couple days ago, I watched about the Modal ontological argument when I Started to think about the fact that axiom S5 (that is used for 3rd premise of the Modal argument) can be used to support a number of self-contradictory positions including an irresistible (or unstoppable) force and unmovable object existing in the same world (what happens if a irresistible force hits the unmovable object?). I spend a couple creating this argument, although most of it was wasted trying figure out how premise 13 should stated.
Axiom S5 states that if it exists in some possible worlds then it exists in all possible worlds. The Logic I am talking about of course is Modal logic, I don't know much about it apart from the axiom I trying to refute.
This argument has premises and a conclusion. it is a Reductio ad absurdum argument you will see in the argument present below.
A Reductio ad absurdum argument works by assuming what your trying to disprove to be true then push that assumption to it's logical (and absurd) conclusion to expose contradictories that the assumption creates. since everything that creates contradictories are false, it logically follows that the assumption the assumption is false.
The argument goes as follows.
1. Axiom s5 (X in some worlds = X in all worlds) is true.
2. It is possible that a unmovable objects exists.
3. If it is possible that a unmovable objects exists, then it exists in some possible worlds. (from 2)
4. If a unmovable object exists in some possible worlds, then it exists in all possible worlds. (from 1 and 3)
5. if a unmovable object exists in all possible worlds, then it exists in the real world. (from 4)
6. It is possible that a irresistible force exists.
7. If it is possible that a irresistible force exists, then it exists in some possible worlds. (from 6)
8. If a irresistible force exists in some worlds, then it exists in all possible worlds. (from 1 and 7)
9. If a irresistible force exists in all possible worlds, then it exists in the real world. (from 8)
10. The idea of a unmovable object and irresistible force existing in the same world is self-contradictory. (from 5 and 9)
11. all self-contradictory ideas are false.
12. any axiom that creates self-contradictory ideas are incoherent. (from 11)
13. Axiom S5 created this self-contradictory idea. (from 10 and 11).
Conclusion: Premise 1 cannot be true. (from 12 and 13)
I want this argument to be critiqued, since I want to see if the argument is logically valid, the logic is sound and the premises are true. The best way to do this to have other try expose the flaws in the argument. I will be surprised if the argument survives the critiquing without any changes to it.