James Anderson recently shared:
Can we prove the existence of God? What exactly does it mean to prove something? What would count as a proof of God’s existence? To explore these questions, let’s consider one popular argument for God’s existence and test it against some different criteria for proofs. Here’s the argument:
1. If God does not exist, there are no objective, culture-transcending moral duties.
2. There are objective, culture-transcending moral duties.
3. Therefore, God exists.
Is this a proof of God’s existence? One suggestion is that any sound argument constitutes a proof. An argument is sound if and only if (a) all its premises are true and (b) it is deductively valid, in the sense that its conclusion follows necessarily from its premises (i.e., it’s logically impossible for the premises to be true but the conclusion to be false).
Is our argument sound? It’s certainly deductively valid: it has the valid argument form of modus tollens (if P then Q; not Q; therefore, not P). Moreover, both of its premises are true. There are indeed objective, culture-transcending moral duties, such as the duty to care for one’s children, and it’s very hard to see what would ground such moral obligations if there were no God. At any rate, I believe that both premises are true, and so do many other people. But does everyone believe both premises? Well, no—and therein lies the rub.
Limitations of Sound Arguments
There’s another obvious problem with the idea that any sound argument amounts to a proof. Consider the following argument for the existence of God:
- Either the moon is made of green cheese or God exists.
- The moon is not made of green cheese.
- Therefore, God exists.
Or this one:
- Everything the Bible says is true.
- The Bible says that God exists.
- Therefore, God exists.
Both of these arguments are deductively valid and have true premises. Yet we can see that there’s something very fishy about the arguments. If someone were to ask you to prove the existence of God, you’d be unlikely to offer either of these arguments with any seriousness. Why? Simply because only someone who already believes in the existence of God would concede the first premise of each argument. The arguments are fallaciously circular in the sense that one would have to accept the conclusion before one could reasonably accept the premises. Even though the arguments are valid and (Christians would say) sound, they’re worthless as proofs. They have little, if any, persuasive force.
Is our original argument circular in the same sort of way? Is it clear that one or other of the premises wouldn’t be granted by someone who doesn’t already believe in God? The argument doesn’t appear to be circular in that question-begging way. After all, there are many atheists who accept that there are objective moral duties (and plenty more who argue as though there are). Furthermore, a number of atheist philosophers have agreed with the first premise of the argument.
This raises a further question and invites a further refinement of our criteria for proofs. If atheists have granted both premises of the argument, and they recognize that the argument is logically valid, why don’t they accept the conclusion that God exists? The short answer is that few atheists would affirm both premises. Those who affirm premise one will typically deny premise two, and vice versa. The explanation for this, of course, is that anyone who accepts both premises is logically committed to the conclusion—and most atheists simply don’t want to accept the conclusion.
Once you see that an argument is logically valid, you can’t consistently affirm its premises and deny its conclusion. So you have two options in order to maintain consistency. You can either (a) affirm the premises and the conclusion or (b) deny the conclusion and at least one of the premises. When presented with an argument like the one above, atheists will typically follow the second option rather than the first. Why? The reasons are complex but the short answer, from a biblical perspective, is simply—human sin. One of the defining characteristics of unbelievers is that they “suppress the truth in unrighteousness” (Romans 1:18).
Next time we will finish up with Part Two: Have a great weekend!