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.