In previous posts (here and here), I’ve written about the need for a clear understanding of logic to separate good and bad thinking. I’ve highlighted the fundamental laws of logic: the Law of Identity (A is A), the Law of Non-contradiction (A is not non-A), and the Law of the Excluded Middle (either A or non-A). These are so fundamental to basic thought, it’s easy to not think about them. Yet remembering these basic, self-evident truths can keep you from falling victim to some surprisingly common mistakes in this age of relativism. Sadly, some Christians have tried to distance themselves from logic, thinking that “God is above logic”. On the contrary, the Bible reveals in its descriptions of God a rich exposition of these truths that shows that logic is part of God’s very nature.
Consider the Law of Identity. Commonly formulated as A=A, this demonstrates why these are called “self-evident” truths – you recognize the truth of it as soon as you see it. There is no proof of this because this is one of your basic building blocks of thought that you can’t break down any lower. Something simply is what it is. How is this demonstrated in Scripture? In the book of Exodus, God speaks to Moses, telling him to go and rescue the Jews enslaved in Egypt. Moses worries that the Jews, who have lived in the polytheistic Egyptian culture for centuries by this point, won’t believe him when he tells them that “the God of your fathers has sent me to you.” He supposes they may ask “What is His name?”, and asks God how he is to answer. God responds with “I Am Who I Am. Tell them ‘I Am has sent me to you.'” This expression of independent, self-existent being is the epitome of the Law of Identity. We can all be identified in relation to someone else. A man may be his father’s son, or his sibling’s brother. There may be hundreds of Johns in a city, tens of John Smiths, only 2 that live on the same street, but only one John Smith Jr on that street. But here, God shows that His name can only relate Him to Himself. He is truly in a category by Himself. And we understand this by the Law of Identity.
Let’s look at the Law of Non-contradiction now. There are several different ways of expressing this, but in general, something cannot be both true and false at the same time and in the same manner. Similarly, something can’t both exist and not exist at the same time in the same way. How is this demonstrated in the Bible? The apostle John records Jesus saying that “I am the way, the truth, and the life”. The book of Hebrews tells us that “it is impossible for God to lie”, and the apostle Paul tells Titus that God “does not lie” and Timothy that “He cannot deny Himself”. Why is this important? Because logic seeks after the truth, and the opposite of truth is a lie. A lie can also be defined as a contradiction, for truth corresponds with reality, while a lie contradicts reality (a contradiction, from the Latin “contra” + “dictio” literally “speaks against itself”). So here we see that because God cannot lie, He cannot violate the Law of Non-contradiction.
The Law of Excluded Middle says that something either is or isn’t, true or false, on or off. There is no middle option between contradictory states. There are times when we may have a spectrum of choices, like when the gas tank is empty, or full, or somewhere in between. The Law of the Excluded Middle comes into play when the choice is between true opposites where one choice is the negation of the other, Instead of “empty” and “full”, the choice is between empty and not-empty, or between full and not-full. God either exists or He doesn’t. Our own belief, unbelief, or agnosticism does nothing to change that objective status. The apostle John tells us that “God is Light, and in Him there is no darkness at all.” It’s either all or nothing.He either exists as morally perfect, without blemish, or not at all.
Now, is all of this to say that God is somehow limited by some man-made rules? Hardly. The laws of logic aren’t made, but discovered. Logic is the lens through which we look to make sense of reality, and it makes sense of reality because it is founded in the nature of the Creator of reality. Rather than limiting God, logic gives us a glimpse of His nature.
 Exodus 3:14, NASB.
 Hebrews 6:18, 2 Timothy 2:13, Titus 1:2, NASB.
 1 John 1:5, NASB.
 D.Q. McInerny, Being Logical: A Guide to Good Thinking, (Random House, 2005), p. 25-30. Though not quoted directly, this short, concise summary of basic logic provided much of the background on the laws of logic referenced here.