God and logic

Many people treat logic as a worldview-invariant criterion. A standard that transcends any worldview in particular. An umpire that adjudicates between one worldview and another.

In light of that, it’s striking to read some of Quine’s statements on the status of logic. After all, Quine was the most distinguished logician of his generation. Yet here are two of his statements on logical necessity:

The modal logic of necessity–necessary truth and necessary consequence–is an extravagant departure from extensionality.  Necessity itself can instead be clearly and usefully construed in one and another relativistic way.

 

I have not been sold on the notion of necessity, the distinction between necessity and contingency, which is what modal logic in its standard interpretation and primary motivation is about.

W. V. Quine, Confessions of a Confirmed Extensionalist and Other Essays (Harvard 2008), 191, 444.

Why does Quine say that? He doesn’t explicitly give his reason, but I assume it’s bound up with his naturalized epistemology. Indeed, the very same essay from which I took the former, he makes naturalistic evolution his point of departure.

On this view, logic is merely the grammar of human thought. Ideas bouncing around the brain. Logic is an emergent property. The laws of logic actually evolve.

But if logic is just a description of how the brain thinks, then logical truths are contingent truths rather than necessary truths. Logic is reducible to human psychology, or higher animals.

Of course, one might say that’s self-refuting. But it only seems that way to our little simian brains. If logic is just a notion in our noggins­–the firing of C-fibers or whatever–then when we intuit a logical contradiction, we’re just staring back at ourselves in the mirror of our minds–the way a cat is deluded by its own reflection. There’s nothing on the other side of the silver.

Necessary truths require some metaphysical underpinnings. Logic alone is not a sovereign god who can dispatch every claimant, for we must also take into account the ontology of logic. As Quine vividly illustrates, logic without firm foundations will sink back into the quicksands of psychologism.

Theology and logic enjoy a symbiotic relationship. If theology can’t do without logic, logic can’t do without theology.