The Leibnizian Cosmological Argument for God

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The Leibnizian Cosmological Argument for God

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Introduction

The Leibnizian cosmological argument (LCA) is a family of arguments having to deal with explaining why the Cosmos (understood as all of physical reality, or the set of all contingent things, or all of creation etc.) exists. The LCA can also ask, “Why is there something rather than nothing?” Arguably, “Why is there something rather than nothing?” is one of the most fundamental questions of philosophy. I believe whereas theism gives a satisfactory answer to this question, atheism does not.

Concepts the LCA Uses

Leibnizian cosmological arguments use a form of the principle of sufficient reason (PSR), a principle saying that everything (of a certain class) has a reason/explanation. The PSR has a number of different forms, but one version of the PSR says “Everything that exists has an explanation for its existence, either in the necessity of its own nature or in an external cause.” What does it mean to exist by the necessity of its own nature? A thing’s existence being metaphysically necessary means it is impossible for it to not exist (whereas contingent things both could exist and could have failed to exist, e.g. my own existence is contingent) and thus metaphysically necessary things exist in all possible worlds (where a possible world is a complete description of the way reality is or could have been like; thus “all bachelors are unmarried” is true in all possible worlds whereas there are possible worlds with different physical laws than ours, hence science’s need for empirical investigation).

Some philosophers and mathematicians think that abstract objects like numbers exist necessarily. I myself think that numbers are more like ideas in the mind and have no more real existence than Sherlock Holmes, but hopefully the idea at least gives some illustration of what it is to have necessary existence. Some people believe that certain moral truths, like “it is not the case that it is morally right to torture infants just for fun” are metaphysically necessary in that they are true in all possible worlds (there is no possible world where “it is morally right to torture infants just for fun” is true).

Here’s one way to look at the explanation of X’s existence being the necessity of its own nature. In regards to the question, “Why does X exist in the actual world as opposed to not existing?” the answer is “The reason why X exists in the actual world as opposed to not existing in the actual world is because X exists in all possible worlds and there is no further reason for why X exists.”

With some conceptions of God, one of the defining attributes of God (along with being transcendent in the sense of transcending the physical world) is that God’s existence is metaphysically necessary, such that if God exists he exists necessarily. God’s necessary existence (along with other attributes) also explains why objective morality exists (for more on that see my entry on Going from Morality’s Existence to God’s Existence).

Varieties of the LCA

Some forms the LCA can take:

1. The argument that asks, “Why does the physical universe exist?” and offers theism as an explanation.
2. The argument that asks “Why is there something rather than nothing?” and offers theism as an explanation. One weakness: Platonists believe that abstract objects (like numbers) exist independently of the mind and have necessary existence, and so Platonists won’t see the need for God as an explanation because Platonic abstract objects exist by the necessity of their own nature. If you’re not a Platonist though, this is potentially a good argument because “Why is there something rather than nothing?” is an excellent question and it seems to be the sort of thing that we should look for an explanation for.
3. The argument that asks, “Why do contingent things exist?” and offers theism as an explanation. This bypasses the problem of Platonism because abstract objects (like the number six) can’t cause anything, including contingent objects. This type of argument is also called “the argument from contingency.”

Let’s label the above three LCA arguments LCA 1, LCA 2, and LCA 3, respectively, and start with LCA 1.

LCA 1

One form of the LCA then is as follows, popularized by the Christian philosopher William Lane Craig:

1. Everything that exists has an explanation of its existence, either in the necessity of its own nature or an external cause.
2. The universe exists.
3. If the universe does have an explanation for its existence, that explanation is God.
4. Therefore, the universe has an explanation of its existence (from 1 and 2).
5. Therefore, the explanation for the existence of the universe is God (from 3 and 4).

Call this argument LCA 1A. Premise 1 is the form of the PSR that the argument uses. According to the PSR, even God requires an explanation for his existence. So what is that explanation? Wouldn’t it be special pleading to exempt God from the PSR? Indeed it would be, but the LCA adherent has a ready reply: if God exists he exists necessarily, and the necessity of his own nature is the explanation of God’s existence. It should be remembered that God isn’t (necessarily) unique in that regard. If Platonic objects exist, the explanation of their existence lies in the necessity of their own nature. That’s the reason LCA 2 won’t be convincing to atheists who are Platonists, because the necessary nature of Platonic abstract objects supplies the explanation of their existence and so we have a non-theistic explanation for why there is something rather than nothing (though that is of no help in explaining the existence of the physical universe or the contingent universe, since abstract objects can’t cause anything).

The above LCA 1 argument is deductively valid, but the premises require justification. I’ll start with the least controversial premises and work my way up.

Justifying Premise 2

Premise 2 is not all that hard to believe (by “the universe” I mean “all of physical reality”). We can point to examples of physical things that exist, e.g. my body, a nearby tree, or perhaps a chair you are sitting on. This premise is pretty uncontroversial, so I’ll say no more about that.

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