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#118 God’s Necessity

July 20, 2009

Dr. Craig,

I really want to learn more about theism but I have hit an intellectual roadblock with God's necessary existence. I understand what it means for an entity to necessarily exist in a logical sense. Yet when you attribute metaphysical necessity to God (de re necessity) my brain gets muddled.

As I understand it, to say that God necessarily exists in the metaphysical (de re) sense, you mean to state that in every world in which God exists, God must exist. Other scholars of a theistic persuasion reinterpret the same point as proclaiming that God existence is part of His essence. But what in the world does that mean? How should I contrast it to logically necessary existence? Moreover, assuming that existence is a property, isn't it the case that you, me and everyone else has existence as part of his or her essence? After all, it seems plausible that there is no possible world wherein I reside and do not exist. Hence, the property of existence is part of my essence.

Finally, do you believe it is logically possible that God does not exist? Please explain your answer.


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    Dr. craig’s response

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    Understanding God's necessity is fundamental to our grasping Who God is, so your question is a vital one, Mikhal. I think some of your confusion may be due simply to terminological muddles, so let's try to clear them up.

    When philosophers speak of metaphysical necessity/possibility, they are thinking in terms of a modality that lies somewhere in between the strict logical modality that characterizes the laws of logic and the broader physical modality that characterizes what is permitted by nature's laws and boundary conditions. Metaphysical possibility has to do with what is actualizable or realizable, what can actually be. So, for example, I would say that it is metaphysically possible that I might have had an alligator body, even though such a thing is not physically possible. But it is metaphysically impossible that I could have actually been an alligator rather than a human being. Metaphysical necessity has to do with what must be the case, even though its denial does not involve a contradiction. For example, I think it is metaphysically necessary that everything that begins to exist has a cause, even though there is no logical inconsistency in saying that a certain thing came into being without a cause. If this metaphysical modality strikes you as rather vague, you're right! What we take to be metaphysically necessary/possible depends on our intuitions about such matters.

    Now de re ( from the Latin, meaning pertaining to a thing) modality has to do with a thing's essential properties. When it is said that a property belongs to a thing's essence or is essential to it, that means that the thing could not have lacked that property and still remained itself. If something loses one of its essential properties, then that thing ceases to exist. A cow, for example, has the essential property of being an animal. If it were slaughtered and ground up into hamburger, then it would cease to be a cow. Properties that a thing has which are not essential to it are called contingent properties.

    So metaphysical necessity and de re necessity aren't the same thing. When we say that God is metaphysically necessary, we mean that it is impossible that He fail to exist. This is a much more far-reaching claim than the claim that "in every world in which God exists, God must exist." When you think about it, anything that exists must have the property of existing in every world in which it exists! So you're right that you, I, and everyone else has existence as part of his or her essence in that sense. Rather the claim here is that God exists in every possible world. What God has that we don't, then, is the property of necessary existence. And He has that property de re, as part of His essence. God cannot lack the property of necessary existence and be God. Of course, if something has the property of necessary existence, it can't lose that property, since if it did, there would be a possible world in which it lacked necessary existence and so it was never necessarily existing in the first place!

    (Be aware, however, that when medieval theologians spoke of existence as uniquely part of God's essence, they were using the word "essence" in a different way. For them a thing's essence defined what it is. In their view only God has existence essentially, since every other being is contingent and so is not defined as something existing.)

    So is it logically possible that God not exist? Not in the sense of metaphysical possibility! There is no strict logical contradiction in the statement "God does not exist," just as there is not a strict logical contradiction in saying "Jones is a married bachelor," but both are unactualizable states of affairs. Thus, it is metaphysically necessary that God exists.

    We have here the germ of the ontological argument for God's existence. For if it is possible that God exists, there is a possible world in which God has necessary existence. But then He exists in every world, including this one. Thus, the atheist is thrust into the awkward position of having to say that God's existence is impossible. It is not enough to say that in fact God does not exist; the atheist must hold that it is impossible that God exists—a much more radical claim!

    - William Lane Craig