The concept of an omnipotent being, namely a being with maximal perfection with respect to power, is sometimes believed to involve a contradiction. The most popular reductio ad absurdum case against the existence of omnipotent being is known as “the paradox of the stone.”
The paradox unfolds as follows:
1. If God exists, then He is omnipotent
2. If God is omnipotent then God can create a stone too heavy for anyone to lift.
3. If God can create a stone too heavy for anyone to lift, then God is not omnipotent since He cannot lift the stone He created.
4. If God cannot create a stone too heavy for anyone to lift, then God is not omnipotent since He cannot create the stone too heavy for anyone to lift.
5. Either way God is not omnipotent.
6. Therefore God does not exist.
Since a person offering this case “is assuming throughout that if there is something specifiable that God cannot do, it follows that he lacks omnipotence” as Thomas V. Morris (1991, 73) correctly observed, clarification of the terms used would help show how weak and unsound this case is.
What do we mean by “a being Y can do x ”? According to Morris, we can mean either ability, Y is “able to do x” or capability, Y is “capable of doing x.” Our questions should be then, does it necessarily mean that Y lacks power to do x, if Y cannot do x? Soundly no. Y might have the power to do x but lack reasons or will or skills or opportunity et cetera to do x. Does it necessarily then mean that Y lacks power to do x, if Y is not capable of doing x? Soundly no again, since Y might have the power to do x but lacks moral justification to do x.
Borrowing Morris’ example, God could indeed create a small stone that no one could lift, by simply making the stone impossible to be lifted by any other beings and vow himself not to lift it. Since God is morally perfect, He cannot break His vow not to lift the stone, thus adding himself to a group of all other beings that cannot lift that stone. We can say, in this state of affair, that God cannot lift the stone, but not because of lack of power but of the promise that a perfect being cannot break.
Michael Tooley’s Solution: Atheist Philosopher’s Critique
Tooley deemed this paradox of omnipotence argument as “clearly unsound.” He contended,
[T]his [unsoundness of the case] can be seen if one simply makes explicit the times at which the being acts, or possesses some property. For suppose A is omnipotent at a specific time t1. Then A can act at that time to bring it about that there is a rock that no one can lift. But at what time does the latter state of affairs first exist? It cannot be time t1, since, I would argue, a cause cannot be simultaneous with its effect. So let us suppose that A acts at time t1 to bring it about that there is, at some later time t2, a rock that no one can lift. It then follows that A either no longer exists at time t2, or does exist at time t2, but is no longer omnipotent. So to bring it about that there is a rock that no one can lift—including himself—an omnipotent being must either commit suicide, or at least bring it about that he is no longer omnipotent at the relevant time. This is not, presumably, something that a sensible person—let alone a morally perfect one—would be likely to do. But there is no contradiction in the proposition that A, who is omnipotent at time t1, either does not exist at some later time t2, or else exists at that time, but is not omnipotent. Accordingly, there is no paradox of omnipotence.(Plantinga & Tooley 2008, 87)
Tooley’s solution is of no use to theists, since they believe God, if he exists, is a being greater than which none can be conceived. Omnipotence and necessary existence in all possible worlds are greatness-making properties that a being none greater than which can be conceived must possess. Is there a possible solution that both atheists and theists would accept?
Thomas V. Morris’ Solution: Theist Philosopher’s Critique
Morris offers two solutions, which I find compelling. Probing what kind of stone a defender of this case is asking an omnipotent God to create that He cannot lift, Morris contended,
But what would such a stone be like? What, for example, would it weigh? If God is omnipotent, then, presumably, he can create stones of any possible weight. But if he is omnipotent, then, presumably as well, for any possible weight n, he can lift stones of weight n. Realizing this has led some philosophers to one of the simplest solutions which has been offered to the stone paradox. They have just claimed that ‘creating a stone which even an omnipotent being can’t lift,’ and all its analytical equivalents, is just an incoherent act-description. And since the phrase ‘the power to create a stone which even an omnipotent being can’t lift’ does not designate a logically possible power, it does not follow from the fact that God cannot create such a stone that God lacks any power required for omnipotence, or that he lacks in any other respect. This solution maintains that the proper answer to our original question is no, but that does not cause any problems for the ascription of omnipotence to God. (Morris 1991, 74)
What if the defender of this case keeps insisting that God creating a stone too heavy to be lifted is a logical possibility. Is it possible that God can create such stone and still be omnipotent? Yes. Morris again argued that it still would not follow that God lacks the power to lift such stone. God could simply vow not to lift the stone, thus it would not be because of inability to lift the stone but moral incapability that God cannot lift that stone. “Thus, lacking a power to lift S [stone] is not lacking a possible power, a power possible to have, and so no such lack would detract from God’s being omnipotent. (ibid 75)
Morris awesomely concluded:
If we choose to say that God cannot create a stone he can’t lift, we can block the inference to his lacking omnipotence and explain the apparent divine inability by characterizing the act-description here as incoherent. If we choose to say that he can create such a stone which, once created, he cannot lift, we can block the inference to his lacking omnipotence by explaining that the subsequent inability to lift cannot be thought of as reflecting the lack of any power it is possible to have. But by either strategy the claim of omnipotence for God is defended.”(ibid 76)
Question: Are you persuaded by the Paradox of the Stone as case against omnipotent God?
Plantinga, Alvin & Tooley, Michael (2008) Knowledge of God. Blackwell Publishing.
Morris, Thomas V. (1991) Our Idea of God: An Introduction to Philosophical Theology. InterVarsity Press.