The Biblical Basis for the Laws of Logic


How They Stem from the Mind of God.

by Dr Jason Lisle

Laws of logic are the rules of correct reasoning.  They reflect the way God thinks and the way we must think if we are to think correctly.  Laws of logic are also called “rules of inference.”  Correct reasoning can never violate a law of logic.  There are many laws of logic.  But three are considered the most basic or primary.  Let’s examine these three and how they stem from the mind of God.

There is the law of non-contradiction.  This law states that a proposition and its negation cannot both be true at the same time and in the same sense.  A negation is the opposite of the original proposition.  It is formed by adding “It is not the case that” in front of the original proposition.  So, if the proposition is “The sky is blue”, then the negation would be “It is not the case that the sky is blue.”  If we label a proposition as p, then its negation would be labeled “not-p.”  The law of non-contradiction requires that one of the two propositions must be false.  So, if I said, “The Sky is blue, and it is not the case that the sky is blue”, my statement would be false according to the law of non-contradiction.  Another way to state the law of non-contradiction is that the combined proposition, p and not-p, is always false.

We also have the law of the excluded middle.  This law is similar but distinct from the law of non-contradiction.  It states that either a proposition is true, or its negation is true.  So, if we have a proposition – let’s call it p, and if that proposition is false, then the proposition not-p would have to be true.  Conversely, if p is true, then not-p is false.  A proposition always has the opposite truth value of its negation.  Another way to state the law of the excluded middle is that the combined proposition, p or not-p, is always true.

There is also the law of identity.  It simply states if p then p.  That is, if p is true, then p is true.  It is an obvious rule, but one that is never violated.  An alternate formulation of the law of identity is: “A thing is itself.”  So, in summary we have:

The law of non-contradiction
The law of the excluded middle
The law of identity

There are many other laws of logic, such as modus ponens and modus tollens.  But the above three laws of logic are often considered the most basic.  They are sometimes called the “three laws of thought.”  Many other laws of logic follow from these three.

But what is the nature of a law of logic?  Can you see one with your eyes?  Can you accidentally swallow a law of logic?  Of course not.  Laws of logic are abstract and conceptual.  They do exist of course, otherwise we could not use them.  But they are not physical.  They are not made of atoms and therefore you cannot see, taste, or touch a law of logic.  We can write a law of logic on paper, but this really is merely a representation of the law –  not the abstract law itself.  After all, if we then erased the sentence, the law of logic would not cease to exist…