Tuesday, April 21, 2009

Can God create a rock he cannot lift?

Can God create a rock he cannot lift?
(Chinese version after English) 神能否做出一塊祂搬不到的石?

We will need to use the Proof by Contradiction:

Definition of Proof by contradiction:
If there is a sentence named "P", if we need to prove P is false, then we can try to assume that P is true first, then logically write down what we know about P. If it ends up something contradict P, then P must be false.

P => Q => S => …….=> ~P    (~P means not P)

Of course, "Q, S...." statements must be true.

Proof: God can create a rock he cannot lift.

First, people want to proof this because they want to proof that God is not almighty. Of course, we need to assume God is Almighty.

If God is almighty (P), then God can create any rock.(Q)
If God can create any rock, then God can create a rock he cannot lift. (S)
If there is a rock that God cannot lift (T), then God is not Almighty(~P)
If God cannot create this rock(Q), then God is not Almighty(~Q)

So P is wrong!!!!!!!! God is not almighty!!!!!!!!

***NNNN NO NO No no no oooo ***

There is something wrong in the proof. "S" is contradict "P". This is logically wrong and contradict to the hypothesis (God is Almighty). This is the same thing as when we ask somebody to create a "circular square" which is contradicting itself.

Therefore, please do not ask me anymore about if God can create a rock he cannot lift. Thank you.



P => Q => S => …….=> ~P    (~P即not P)
若中間所有的步驟在邏輯上沒有錯誤,那麼即說明由P這假設開始,竟能推論出 ~P!

那麼問題一定在P本身!P一定是一句錯或假的句子了。這叫做「反証法」(proof by contradiction)。這方法的特色就是要從一個假設開始。


「神能否做一塊祂舉不起的石頭 ?」

=> 如果神是全能的 , 祂必定能造出任何石頭 (Q)
=> 但如果神能造出任何石頭, 祂必定能做一塊祂舉不起的石頭 (S)
=> 那麼就有一塊石頭是祂舉不起的(T)
=> 祂就並非全能(~P);
=> 若果神不能造出一塊這樣的石頭(~Q)
=> 那麼祂也不是全能的(~P)。

以符號來表達,P => Q => ( S => T => ~P) or (~S => ~Q => ~P) => ~P∴ P本身不能成立。


不過,S本身已經和預先假設了的P有矛盾,因為S的意思是指有一塊神舉不起的石頭存在,這與最初的假設P有矛盾,在這情況下,邏輯上不能將S應用在申述之內。另外~S的意思是指有一塊石頭是神不能造出的,本身與P這假設有矛盾,也不能應用在申述之內。因此,在假設了神是全能的前題下,我們不能用「神能否造塊祂舉不起的石頭?」來否定這前設。總括來說,若假設了神全能是對的,這一句:「神能造塊祂舉不起的石頭 or 祂不能造塊祂舉不起的石頭」是一句內在矛盾的句子,就如「神能造個方形的圓 or 神不能造個方形的圓」矛盾一樣。(「方形的圓」的矛盾很容易看到,因為方和圓並不相容;而上述句子的矛盾是因「神是無所不能的」這前設下產生的.)

Thank you,


Note: One possible objection to this line of reasoning is "God is not bound by the rules of logic, as he created logic, therefore he can do the logically impossible as they are only logically impossible from our point of view". If this were the case, however, it would seem to be impossible for anyone to ever know anything about God at all, or attempt to understand him using reason and logic. It would make no sense for any theist to attempt to describe the character of their god as, for instance "good, merciful and loving" because there would be no reason to think that this could be true. You could not say, for example, that God is good because he has healed a person, as an illogical God could just as easily have done it for any reason at all other than goodness - by our standards it might appear to be "good", but that would be no reason to assume that it was good as far as God was concerned. ]

Ah B

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