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The 'Big Rock' Paradox

  1. Mar 17, 2009 #1
    I was first introduced to this thought-experiment upon reading Stephen Hawking's A Brief History of Time . Suppose an omnipotent being exists. If it does, it would be able to do anything (by definition!). Therefore, it would be able to produce a rock it couldn't lift. Therefore, it wouldn't be able to do anything it wants, therefore it wouldn't be omnipotent. What do you think?
    Please nothe that I have phrased this thread to avoid it being locked. Please keep that in mind if you comment.
  2. jcsd
  3. Mar 17, 2009 #2
    An all powerful being, would be capable of making itself as 'physically strong', at any given moment, as it wanted to. So it makes itself physically capable of lifting a certain amount. Then it makes a rock that weighs more. Now it can't lift it. Then it decides it really wants to, so it makes itself physically stronger. Voila.
  4. Mar 17, 2009 #3
    Hmmm.... your argument is invalid due to the definition of omnipotence. An omnipotent being can't make itself stronger to lift a rock ... its omnipotence already ensures it can do that.
  5. Mar 17, 2009 #4

    Ivan Seeking

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    I prefer the other version of this question: Could God make a salsa so hot that he can't eat it?
  6. Mar 17, 2009 #5
    It ensures that it 'can', not that it 'must' in any particular instance.
  7. Mar 17, 2009 #6


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    To me, this has little to do with a thought-experiment and much more to do with the semantics of "omnipotent".

    i.e. so there's a word in the English language wherein you can form sentences that are seemingly paradoxical. So what?
  8. Mar 17, 2009 #7
    The fact that 'omnipotent' is paradoxical means it can't exist.
  9. Mar 17, 2009 #8
    But since it CAN'T, it isn't omnipotent.
  10. Mar 17, 2009 #9
    It can when it wants to. And yes, its a word game.

    But just because our understanding of something seems paradoxical, doesn't mean that something doesn't exist.
  11. Mar 17, 2009 #10


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  12. Mar 17, 2009 #11
    All hail the Big Rock.
  13. Mar 17, 2009 #12
    Liars are paradoxical, as I am sure you know, but they do exist.
  14. Mar 17, 2009 #13
    Maybe its Schroedinger's rock.
  15. Mar 18, 2009 #14
    Liars aren't paradoxical. People who admit that they are liars are paradoxical.
  16. Mar 18, 2009 #15
    Suppose a right-wing radio commentator were to say, "I always tell the truth." That's not paradoxical; it's merely that we ordinary mortals are incapable of understanding the meanings of superior beings. So might it be with gods.
  17. Mar 18, 2009 #16


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    This is actually a form of Russell's paradox. (Define the set of all sets which do not contain themselves as elements and ask if that set contains itself.) You can form this when you allow both open ended definitions and circular or self reference.

    This is the problem with open ended definitions e.g. omnipotence. To solve this one you just have to acknowledge that "a rock that God couldn't lift" is an ill defined concept as given any rock that could exist this God could both create and lift a larger one. Omnipotence only covers the ability to effect well defined states of reality.
  18. Mar 18, 2009 #17


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    It's called the http://en.wikipedia.org/wiki/Omnipotence_paradox" [Broken].

    As far as Christianity is concerned, a fairly authoritative answer was given by http://www.ccel.org/ccel/aquinas/summa.FP_Q25_A3.html" [Broken] in Summa Theologica's first book.

    Not really an interesting question IMHO.
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  19. Mar 18, 2009 #18


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    Which is actually a subset of http://xkcd.com/468/" [Broken]. o:)
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  20. Mar 18, 2009 #19
    Omnipotent beings are then not impossible in general, only those omnipotent beings that make rocks so heavy that they cannot lift them are paradoxical. In other words, any liar and any omnipotent being has the potential to be paradoxical.
  21. Mar 18, 2009 #20
    What if the god moved the universe so the rock will have, in effect, been moved?
  22. Mar 21, 2009 #21
    Actually if omnipotence means to be able to do anything, that means an omnipotent being could be something and not be something at the same exact time. It could do everything it couldn't do and it could be paradoxical and perfectly fit within human logic and reason. It could have no beginning and no end while having both and could and couldn't be grasped. So really, this 'paradox' proves the oneness of everything and nothing.
  23. Mar 21, 2009 #22
    Doesn't the question rather unnecessarily anthropomorphize the omnipotent being? It seems rather pointless. Compared to a guppy I'm a rather powerful being though it may wonder what is so special about a being unable to breathe water.
  24. Mar 22, 2009 #23
    Suppose I have a computer powerful enough to simulate a planet like the Earth complete with people living on it down the the molecular scale. Then, I could play God in that world by modifying the simulation. I put on my virtual reality helmet, and the simulation simulates me (God) in that world.

    Then, since I'm not bound by any laws of physics that operate in the virtual world, I cannot make a rock that I can't lift. But it could be that there are some actions that would cause the computer to crash when performed by me.
  25. Mar 22, 2009 #24
    Thank you for this comment. These is another aspect that I especially dislike in this paradox. It is restricted to an omnipotent being undergoing time (creating an object and then facing a paradox). Now consider a Leibnizian conception of omnipotent being, say for definiteness "a theory of everything" (I'm simplifying of course, but hopefully not oversimplifying). Then I hope you can see how such a conception does not undergo time. I am not defending any conception over another, neither do I think that would be interesting, I am merely trying to point out a specific example, which I think respects the general criterion provided by
    By the way,
    was quite funny :

    Last edited by a moderator: May 4, 2017
  26. Apr 18, 2009 #25
    Let Z be an omnipotent being.

    Z has a rock fetish. Z thought about the large rock idea. (We are not certain if it ever happened.) Z then decided to make a rock, to be called "little mu", that was so incredibly difficult to detect that even the all-powerful Z could not detect it. Can Z ever be sure that little mu has been created?

    Some people in this discussion have come close to my stance on these "paradoxes". We are arguing using our human logic. But, how can we be sure that such logic applies to the realities and lives of the all-powerful, all-knowing? What we see as a paradox might not be in some ultra-nonhuman-impossible for us to follow-hyperlogic.

    Here is another lil' diddy ---
    Anyone who has seen the Incompleteness Theorem may have run across this "paradox": Can Z know all the true statements of Number Theory? (If Number Theory is consistent then there is a contradiction for Z would be a truth predicate.)

    My response is this... Yes because Number Theory is inconsistent, so every statement is provably true (and at the same time false.) But Z does not want us to be afraid, and if 1+1=2 leads to a contradiction we would be. So, Z makes sure that any inconsistency is out of reach. Whenever we get close to a proof of a contradiction, Z simply redoes the (faulty) Model of Number Theory so that the contradiction is further away.
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