It is one of the axioms of theistic thinking that logic, or more specifically, the rules and axioms of logic, come from God. This is the underlying assumption in certain theistic arguments, and it was the basis of the Lord of Non-Contradiction theistic argument that I discussed in a recent post. In fact, the notion that rational thought can only be the product of a divine thinker who somehow endows the human soul with his rational faculty is pervasive in theistic philosophy. But this idea has no justification. It is merely a presumption that theists make.
One of the points I made in my discussion of the Lord of Non-Contradiction argument is that the laws of logic are not necessary truths. My reason for making such a statement is given in somewhat more detail in the comments to that post, where I answered the objection of Don McIntosh:
Skeptical's brash denial of the premise that logical axioms are necessarily true misses the point. The whole purpose for the philosophical notion of modal logic and possible worlds is to ascertain what may be possible or necessary according to the rules of logic. Clearly if there is any world at all that is "not possible," it's one in which the rules of logic do not hold!Don believes that there is no possible world in which the rules of logic don't hold. My answer to that is to recognize what all Christians believe: a non-material world, where God can do what he pleases, and logical conundrums like the holy trinity can exist. Does the trinity violate the logical law of identity? Yes, it does. That's why they call it a mystery. Christians believe that it is a logical truism that something cannot come from nothing. But if that's the case, then God couldn't have made the universe from nothing, either. What they fail to recognize is that in God's world, it is possible to violate logical rules that apply to us in our material world. Not that I believe in this immaterial realm where God lives, but Christians certainly do. So if Christians want to be honest, they have to admit that they believe there is a possible world where the rules of logic that apply to us humans don't necessarily hold force.
Even though they insist that God can't do what isn't logically possible, they nevertheless believe that God does violate the same rules of logic that apply to us in our world. Everything that begins to exist is caused by something else, they say. But God exists necessarily. God is the exception to the rule that applies to everything in our world. In our world, the laws of reality are what they are, and there are no exceptions. But God isn't from our world. He's from a place where the same rules don't apply. This talk about the necessary existence of God is either an escape clause that allows a supposed God to violate the logical rules of our world, or an admission that the same rules of logic don't necessarily apply in all possible worlds.
To illustrate my point further, let's consider the theistic arguments about the fine-tuning of the universe. Christians believe that our physical world is just one of many possible worlds, where physical reality could be very different from what we see in our world. Our world is what it is because God made it that way, but not necessarily so. The laws of physics aren't necessary truths, they say, and they certainly don't apply in the non-physical realm of existence (God himself is not subject to the laws of physics), but they reflect the reality of our physical world as it has been created by God. So why, then, should they insist that logic is different? Logic simply reflects the reality of our physical world, but God, in his immaterial realm of existence, can still do things that violate the rules by which our physical world abides. It stands to reason that if God can conjure up whole worlds, God can put two balls into an empty basket, and then pull three balls out of the basket, if he so desires. That's something that we can't do, because we are bound by the logic of our physical reality. But in an immaterial world where our brand of physical reality doesn't apply, anything can happen. Who's to say what the rules are? Who's to say that God can't do whatever he pleases in his own immaterial realm?
And that brings me to the larger point. The laws of logic are physical, and they are contingent upon the physical world, because without physical reality, we have no means by which to ground our logical understanding. These laws reflect the physical reality of our world, and they are just the same as the laws of physics, in that regard. In fact, logical and physical laws can't be separated. Perhaps some physical laws could be modified without changing our logical reality, but at the most fundamental level, the laws that we recognize simply reflect the reality of our physical world. Could they be different in some other possible world? We have a hard time understanding how that could be the case, because we only know the laws that apply to us in our world. And that's why Don McIntosh insists that there is no possibility of any other logical reality. He knows the logic that applies to our world, and thinks that the same logic must apply to all possible worlds. But if we're talking about a possible world that is non-physical, why can't it have its own logic that's different from ours? If it's not grounded in any physical reality, anything goes. McIntosh forgets that his own God already does violate the physical and logical realities that we live by. So he's contradicting himself, because he already believes in a possible world (the immaterial realm of God) where the laws are different, or don't apply the way they do for us in our world.
I know that many will object that physical and logical laws are different. Physical laws apply to the way physical things behave, and logical laws apply to conceptual things, or propositions. It's true that we think of logical laws as being conceptual, but only because we have abstracted them to apply to conceptual situations. How do we come to understand the fundamental laws of logic in the first place? By observing the reality of our world. It's no different from the way we gain an intuitive understanding of physical laws. We grow up seeing how things work, and that physical reality is modeled in our brains. How can we catch a ball in flight? Because we've seen the way things move, and we have an intuitive understanding of where the ball will go, and how long it will take. Why do we have an intuitive understanding of the law of identity? Because that's what we have seen with our own eyes from the first moment in infancy when we began to look at our world and make sense of it. There's nothing conceptual about it. It's reality. It's what we observe. It's not something we had to learn in school, and it's not something that God whispered in our ears.