Existence of God (part 25)
Transcript of William Lane Craig's Defenders 2 class.
Excursus: Natural Theology
§ V. Ontological Argument
We have been talking about the Ontological Argument for God’s existence. You will remember I said that steps (2) through (6) of this argument are relatively uncontroversial – they really just follow by definition once you understand the concept of a maximally great being (which, you will recall, is a being that is omnipotent, omniscient, and morally perfect in every possible world). So the really crucial, controversial premise in the argument is premise (1) – possibly, a maximally great being exists.
We saw that it is not enough that that is epistemically possible – that is to say, possible “for all we know.” It is required that this is metaphysically possible. So the question is, what warrant is there for thinking that it is metaphysically possible that a maximally great being exists? I have been arguing that there is a sort of intuitive warrant for this first premise. When we think about the concept of a being which is omnipotent, omniscient, and morally perfect in every possible world, we see that this is a coherent concept. It is not like a married bachelor or a round triangle. We can see that this is a coherent idea and is something that could possibly exist. This gives some intuitive warrant for thinking that the first premise is indeed true.
We saw how critics of the argument will often try to parody the argument by thinking up analogies like a greatest conceivable island or a necessarily existent lion. If they possibly exist, they will exist in every world and therefore exist in the actual world. But I argued that when you think about those concepts, you can see that, in fact, they are not logically coherent concepts. The idea of a necessarily existent lion is incoherent because such a beast would have to exist in every possible world, including universes in which the entire universe is just a single cosmological singularity of infinite density, pressure, temperature, and so forth. Anything that could exist in such a state just is not what we mean by a lion. Similarly, with regard to a maximally great island, there can always be more palm trees or more hula girls. So the idea of a maximally great island also is logically incoherent. These attempts to parody the argument really don’t undercut the intuitive warrant we have for thinking that the existence of a maximally great being is possible.
Perhaps the greatest challenge to this appeal to intuition would be to say that it is equally possible to think of the concept of a quasi-maximally great being. That is to say, a being who exists in every possible world but isn’t maximally excellent in every possible world. Perhaps, for example, he might be omnipotent and he might be morally perfect, but maybe he doesn’t know all truths. Maybe he is not omniscient. He might be like the God of open theism which lacks foreknowledge of future contingent events. He has perfect knowledge of the past and the present, but he lacks knowledge of the future. Such a being would merely be quasi-maximally great, and this doesn’t seem to be an incoherent concept. We seem to be able to conceive of a quasi-maximally great being, from which it would follow that a quasi-maximally great being would exist, which seems absurd. That would be an attempt to parody the argument and say we similarly have no warrant for thinking that a maximally great being possibly exists.
Is this correct? If we are warranted in thinking that it is possible that a maximally great being exists, are we equally warranted in thinking that a quasi-maximally great being exists? I don’t think so. When you think about it, maximal greatness is logically incompatible with quasi-maximal greatness. That is to say, if there is a maximally great being, then there cannot be a quasi-maximally great being in any world with him.1 Why is that? By definition, a maximally great being is omnipotent and all-powerful. That means that nothing else can exist outside of his creative power. If there is any thing else that exists, that thing would be in the creative power of the maximally great being. And that means the maximally great being must have the power to refrain from creating anything else at all. So there must be possible worlds in which the maximally great being exists, but there is nothing else in that world. He refrains from creating anything else. But that means, therefore, that quasi-maximal greatness is not possibly instantiated after all if maximal greatness is because a quasi-maximally great being has to exist in every possible world (by definition). But what we have just seen is that there must be possible worlds in which it does not exist if there is a maximally great being. So it turns out that these two kinds of being are incompatible with each other. There cannot be both of them.
So if it is possible that maximal greatness is instantiated, it follows that it is logically impossible that quasi-maximal greatness is instantiated. It is not true that our intuition that a maximally great being is possible is undermined by an equal intuition that a quasi-maximal great being is also possible. Because that latter intuition – a quasi-maximally great being is possible – depends on the assumption that there is no maximally great being, that such a being cannot possibly exist. But that begs the question.
Moreover, any intuitive warrant that we would have for thinking that there is a quasi-maximally great being is parasitic upon our intuition that a maximally great being is conceivably possible. The only reason why you would think that quasi-maximal greatness is possibly instantiated is because you have an intuition that maximal greatness is possibly instantiated. So there really isn’t any grounds for thinking that if maximal greatness is possibly instantiated, then also quasi-maximal greatness is equally plausibly instantiated. In fact, quite the opposite is true. Our intuition that there is possibly a maximally great being actually undermines any warrant for thinking that it is possible that there be a quasi-maximally great being.
Defense of Premise (1)
We have some real good intuitive warrant for thinking that premise (1) of the Ontological Argument is true. Intuitively, the idea of a maximally great being seems to be a coherent concept and that therefore such a being is possible. But is there any additional evidence or reason to think premise (1) is true apart from its intuitive warrant? Alvin Plantinga gives a clue when he says, “If we carefully ponder the key premise and the alleged objections to it and if we consider its connections with other propositions we accept or reject and we still find it compelling, then we are within our rational rights in accepting it.” Here Plantinga suggests, not simply appealing to the intuitive warrant for premise (1) that we can just see that maximal greatness is a coherent idea, but he says consider its connections with other propositions we accept. Weigh it in light of other truths that we know about and see if we don’t come to think that maximal greatness is possibly instantiated on that basis.
How might we do that? We might consider, for example, other arguments for the existence of God. Think, for example, of Leibniz’s Argument from Contingency that we talked about. Remember this argument says that everything that exists has an explanation of its existence, either in the necessity of its own nature or else in its external cause. And then, secondly, if the universe has an explanation of its existence, that explanation is God.2 Thirdly, the universe is an existing thing. From those three premises it follows that the explanation of the existence of the universe is God. Leibniz’s Contingency Argument, if it works – and I think it does – , gives us a metaphysically necessary being who is the source of all reality outside himself – the ground of being and the explanation for the existence of everything other than itself. The Leibnizian Cosmological Argument gives us good grounds for thinking that there is a metaphysically necessary being which is all-powerful and the Creator of everything else that exists.
Moreover, think about the Moral Argument for God’s existence. Remember, when we looked at the Moral Argument, I argued first that if God does not exist, then objective moral values and duties do not exist. Secondly, but objective moral values and duties do exist. Therefore, it follows that God exists. If the Moral Argument works, it gives us a God who is the ground of moral value and moral duties. One of the interesting things about moral principles is that at least some of them seem to be necessary truths. They are true in every possible world. As the naturalist philosopher of science Michael Ruse has said, “The man who says that it is morally acceptable to rape little children is just as mistaken as the man who says, 2+2=5.”3 Notice here Ruse equates the truth of a moral statement with a mathematical truth, which is necessarily true – true in every possible world. So it would follow that certain moral truths are necessary truths, and therefore if God is the ground for these moral truths, it follows that God must exist in every possible world as the source of moral value and our moral duties. In other words, the Moral Argument gives us a necessarily existent being who is perfectly good and the ground of moral values.
Thirdly, think about a Conceptualist Argument for God’s existence. This would be an argument for God as the ground of abstract objects like numbers and propositions. It might go like this:
1. Abstract objects are either independently existing realities or else concepts in some person’s mind.
2. Abstract objects are not independently existing realities.
From which it follows,
3. If abstract objects are concepts in some person’s mind, then an omniscient, metaphysically necessary being exists.
Why? Because these abstract objects are necessary in their existence. Mathematical objects, if they exist, like the number 2, exist in every possible world, and there are too many of them to be contained in the mind of any finite person. Only an infinite mind, an omniscient mind, could ground all mathematical and logical truths. So if abstract objects are not independently existing realities but are concepts in some person’s mind, they must be concepts in the mind of an omniscient, metaphysically necessary being. From which it follows,
4. Therefore, an omniscient, metaphysically necessary being exists.
If one finds this argument persuasive, it would give you God as a metaphysically necessary and omniscient being.
Summary and Conclusion
Put these three arguments together, and you’ve got (1) a metaphysically necessary being which is the source of all reality outside itself (Argument From Contingency); (2) a metaphysically necessary being which is morally perfect and the ground of moral value (Moral Argument); and (3) a metaphysically necessary being which is omniscient (the conceptualist argument). Put all of these together, and this seems to give good grounds for believing that a maximally great being possibly exists, a being which is metaphysically necessary, omnipotent, omniscient, and morally perfect. So these sorts of arguments might give us good grounds for thinking that the first premise in the Ontological Argument – that possibly a maximally great being exists – is in fact true.4
At this point, the question arises whether the Ontological Argument has not, then, become question-begging. What do I mean by that? An argument is question-begging if your only reason for accepting a premise in the argument is that you already believe the conclusion. So you are, in effect, reasoning in a circle. The reason that you believe the premise is that you already believe the conclusion. In this case, it might be that you believe that it is possible that a maximally great being exists because, on the basis of these other arguments, you already believe that a maximally great being does exist. You believe that such a being does exist, and therefore it is possible that it does exist. That would seem to be question-begging.
I think that this misgiving about the argument may result because of a misconception of the project of natural theology. It seems to conceive of natural theology in too linear a fashion. We should not think of the arguments for God’s existence as links in a single chain, where the chain is only as strong as the weakest link in the chain. Rather we ought to think of the arguments for the existence of God as being links in a coat of chain mail, where all of the links reinforce one another and the mail is not as weak as the weakest link. In that way we can think of the Ontological Argument as part of a cumulative case for theism in which a number of factors simultaneously combine to lead one to the overall conclusion that God exists. In that sense, Anselm may have been wrong in thinking that he had discovered a single argument which, all by itself, independently of anything else, served to demonstrate God’s existence with all his superlative properties. Nevertheless, I think Anselm’s argument does have a part to play, along with the other arguments, in an overall cumulative case to show that God as a supremely perfect being does exist.
That brings us to the end of the discussion of the Ontological Argument. The reason we have spent so much time on natural theology is because, in an increasingly secular society such as we have in the West, it is vitally important that we as Christians be able to defend this absolutely foundational truth of our worldview, namely, that God exists. If this goes, everything goes. So it is vitally important that we as Christians be prepared to engage people in our increasingly secular society with good arguments and evidence for why we believe that, in fact, God exists.
The question arises as to whether or not arguments for the existence of God are necessary in order for belief in God to be rational or warranted. Is a person irrational to believe in God if he has no theistic arguments such as we discussed? Or is it unwarranted to believe in God without these sort of arguments? That raises the question as to whether or not belief in God can be rational or warranted in the absence of the arguments of natural theology. That will be the question covered next time.5
3 Michael Ruse, Darwinism Defended, (London: Addison-Wesley, 1982), page 275
5 Total Running Time: 19:25