"Look folks, whether you agree with me or not, 220 posts ago, I asked how universal, abstract, invariants such as the laws of logic make sense in the atheist worldview. Don't you find it odd that no one has answered that yet?"
As I just explained here, my criticism of Sye’s argument doesn’t require that I possess any answer to this question. But, let’s look at it anyway.
What is an atheist world view?
Simply put, it’s a view of what there is that doesn’t include God. That’s it. Atheists don’t have to sign up to materialism, reductionist or otherwise. They can be substance dualists, property dualists, etc. etc. They can also allow for a Platonic heaven of abstract entities, if they wish.
Thus an atheist world view can include abstract and objective laws of logic.
But Sye is really pushing two different questions:
1. How can the laws of logic possibly exist without the Christian God?
2. How do you justify your use of the laws of logic?
So, while he will no doubt come back to me on my preliminary answer to 1, let’s turn to 2.
Justifying logic is tricky. Here’s one reason why. If such a justification takes the form of some sort of inference, it will itself make use of logic. And so the justification will be circular, and thus no justification at all!
Oh dear! And oh dear for Sye too, if he uses an inference to justify logic, which he does!
So there’s a general sceptical problem here, whether you happen to believe in the Christan God or not.
How to sidestep the problem? One possibility would be to remind ourselves that not all justification is inferential. I am justified in supposing there is an orange on the table in front of me, say, because I can just directly see it there. I don’t infer the orange is there. Its presence is just directly revealed (a "revelation" if you like!)
Now, if that is right - if such non-inferential, perceptual justification is possible - then one possible justification of the very basic rules of deductive inference might be that we can just directly see that they are truth-preserving.
Of course, Sye might not like this justification, but notice:
(i) he himself faces the sceptical problem – appeal to the Christian God doesn’t help.
(ii) Worse still, appeal to the Christian God as a justification in any case looks like an even worse bet given the overwhelming evidence against the Christian God's existence (see my “The God of Eth”).