There is much talk about logic today. It is obviously used significantly in discussions with philosophers and mathematicians. It has also been a tool of some (particularly presuppositional) apologists to argue for God. They insist that atheists cannot account for logic since it is immaterial and universal. Since logic undeniably exists, then something else immaterial and “universal” must also exist to account for it, namely God. This understanding of logic is taught as if it is some ephemeral abstract notion or set of principles of reason that “exists” only in the mind with no basis in physical reality. That is, according to this argumentation physical reality cannot account for the principles of logic. Nothing could be further from the truth. The principles of logic, such as the principles of identity, excluded middle, and non-contradiction are not just principles of rationality. They are principles of being. Let’s look to see what they are and why they must be grounded in reality and not thought.
The Laws of Logic
The law of identity states that something is identical with itself. If a thing is “A” then it is “A”. If something is a tree, then it is a tree. This seems rather mundane and uninformative; however, try imagining reality if this were not the case. The principle of excluded middle says that something is either “A” or “non-A”. It is either a tree or a non-tree. There is no middle ground (the middle ground is excluded). The law of non-contradiction says something can’t both be “A” and “not-A” at the same time in the same sense. That is, it can’t be a tree and a non-tree simultaneously.
We get our understanding of these principles from the world around us. They are not just principles of thought, but of being. The law of non-contradiction is not just that a statement can’t be both true and false. The law of non-contradiction is that something in existence can’t be and not be simultaneously in the same way. In other words, a tree can’t be a tree and not a tree at the same time in the same sense. These laws are thus grounded in being and abstracted via our knowing process. We have experience of reality and then induce said principles of being and know that they apply to all thought and experience.
Another way we know the laws of logic is that they are undeniable. One cannot deny something like the law of non-contradiction without using it. If one attempted to do this, he would be forced into saying that his position is true and not false, and that the opposite opinion would be false and not true. We don’t argue from more foundational principles to arrive at these principles of logic. They are first principles of thought and being. The are first because they are foundational and self-evident. They can’t be denied. Further, they don’t require, nor could they require, antecedent proof. Such proof would have to use the laws of logic.
The Source of Logic
While these laws are undeniable and are self-evident, the source of our knowledge of them is still physical reality. Physical reality is known directly and is evident to our senses. Note I said “evident” not “self-evident.” Propositions are self-evident when we know their meaning. “Bachelors are unmarried men” is a self-evident proposition because as soon as we know the meaning of the terms and the proposition as a whole, we know it is true. However, things are evident to our senses. I do not need an argument that there is a tree outside of my window. I simply see it. Thus, things are evident and the laws of logic are self-evident and undeniable. (I realize I am skipping over a veritable wonderland of skepticism and rationalism which I have no desire to deal with here. I simply don’t think I need to “justify” the existence of something I just ran my car into. If someone honestly doubts the existence of external reality, I would submit that his problem is not philosophical but psychological and he needs to seek medical treatment immediately.)
Of course, such principles can be applied to thoughts and propositions that don’t say things about reality. Logic can be applied to fictitious beings and propositions that say something like, “All monsters live in London.” However, such fictitious beings and propositions are still based in being—that is, things that exist extra-mentally. While a fictitious being doesn’t exist in reality (by definition), we get the concepts of things like monsters from reality. In other words, following the great empirical maxim, “All knowledge is grounded in reality,” we don’t have any new ideas, even of fictitious monsters, that are not tethered to or grounded in reality.
Why the “Existence” of Logic Can’t Prove God
This is why the presuppositional argument for the existence of God from logic fails. A common argument from them is that atheists cannot account for logic. Logic is immaterial and universal, they say, and as such, atheists can’t account for anything that is immaterial and universal. But if what I am arguing for is true, the presuppositionalist’s argument is not successful. This is because atheists can account for logic, because logic is grounded in reality and being. Yes, God is being as such, and as “being” the laws of logic are tethered to God. (God is God, God cannot be non-God, etc.) That is, in a sense they are antecedently grounded in God because they would be the case even if the physical realm did not exist.
Another important note is that the laws of logic are not really immaterial. Sure the abstracted propositional form of being such as “A tree can’t be a tree and not a tree simultaneously” can be immaterial. But if logic is not merely a rational enterprise and is a second order based on the first order of physical reality, then the basis for logic is not immaterial. Our abstractions of the principles are mental, such as numbers, but many, if not most, philosophers do not think that numbers are real. They like logical principles are abstracted from the real world. The number 2 does not exist. But I can say there are two trees. The two-ness is simply the addition of one more tree than the first. Math then is like logic in that the numbers are abstracted from the material world and then one can perform mental operations. But these numbers do not exist (unless one holds an extreme Platonic view).
And as such, the atheist can account for logic by its foundation in sensible objects—just like he can account for numbers. Thus, the presuppositional argument for logic is going to reduce to some cosmological argument that says the universe needs a grounding in something other than itself.
So, there is where we get logic and why we can’t use it to show God exists.
Dr. Brian Huffling
Dr. Brian Huffling’s research interests include: Philosophy of Religion, Philosophical Theology, Philosophical Hermeneutics, and general issues in Apologetics and Biblical studies. See his personal blog here.