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Proof of Anything (Posted on 2003-12-13) Difficulty: 4 of 5
Here is a nice little paradox:

Statement S: If S is true then God exists
Logically, statement S must be either true or false.

1. Suppose S is false.

2. If S if false, then any statement that starts with "If S is true..." is true *(see note)

3. Specifically, the statement "If S is true then God exists" would be true

4. This is exactly what S says, so S would have to be true

5. This is in contradiction with 1., so S cannot be false.

6. Therefore S is true.

7. So the statement "If S is true then God exists" is true.

8. By modus ponens, since S is indeed true, then the second half of that statement is true.

9. God exists.

Note of course that you can make the same argument to prove that God doesn't exist, or anything else.
What, if anything, is wrong with this proof?

*Note: This is the part that I expect most people will comment on. It is one of the standard logical rules that if something, A, is true, you can say "If (~A) then..." and that will always be true. For instance, I could say "If George Washington is alive then the moon is made of cheese" and that would be considered true in natural logic.

See The Solution Submitted by Sam    
Rating: 3.6250 (8 votes)

Comments: ( Back to comment list | You must be logged in to post comments.)
re: God's existence: | Comment 27 of 44 |
(In reply to God's existence: by Benjamin J. Ladd)

"And remember: I'm not a logician! "

obviously not. you have absolutely no clue! the problem has nothing to do with god's existence. the problem is about bad logic. it would make no difference if instead of saying "if S is true then god exists" it said "if S is true then i am wearing underwear". the same rules would apply and there would be a paradox, and we would be presented with the challenge of solving that paradox.

i can't believe you took the time to write all that, and thought that much about the problem without realizing that it has nothing to do with god at all.
  Posted by donnmike on 2003-12-16 21:03:57

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