The Laws of Logic


This is obviously not a question, but I felt that it would be an important topic to cover as we continue to look at various questions about God, His people, His Word, His Son, etc. Particularly for when we start delving into some of the more philosophical questions that I have on my list.

The Laws of Logic are a set of axioms which we know to be true typically because if they were not, we would not have the ability to do or to know pretty much anything. If the Laws of Logic were not true, there could be no knowledge, no society, no safety, etc.

There are quite a number of logical laws, but I would like to lay a brief foundation here by focusing on the three main laws that I will reference most often whenever I post certain ideas and concepts here.

The first is the Law of Identity. This law states, essentially, that a thing is what it is and it is not what it is not.

I know. That sounds so intuitively obvious that it almost seems insulting to have to articulate it. However, it is a vitally important law to keep at the forefront of one's mind when evaluating arguments, claims, statements, propositions, conclusions, etc. The reason I bring it up here is because, like the other two laws I will cover here, it can actually get mixed up pretty easily with clever rhetoric, double-talk and misdirection.

Another fairly obvious one, to a certain degree, is the Law of Non-Contradiction. In it's formulaic form this law states that "A cannot equal Not-A at the same time and in the same way." Unlike the Law if Identity, this one can more easily be misunderstood or misapplied...mostly because of those last two caveats, "at the same time" and "in the same way." Often, people will argue that something is a contradiction when it is actually not. The way they do this is to attempt to show that a particular conclusion is based on the idea that "A is equal to Not-A" but they fail to adhere to one of these last two very important aspects of this law.

As an example, if I were to say something like "I do not have a car" and then a few minutes later, I mention something about my Toyota Camry, someone might say that I have just contradicted myself. Either I don't have a car or I do have a car, but they can't both be true. Right? But, what if my statement "I do not have a car" was referring to the fact that my Camry was at the shop getting a new set of brakes, so I did not have access to my car. Now, you can see that this no longer violates the Law of Non-Contradiction because the "way" in which I "do not have a car" and the "way" in which I have a car are different.

This law has more influence and direct bearing on our world than most people realize. It is because of the Law of Non-Contradiction that I can safely drink a glass of water and know that it is not battery acid. 
Because battery acid is not water and I know, based on this law, that water cannot be water AND be not water (some other substance, like battery acid) at the same time and in the same way.

More could be said about this particular law, but before we make things more confusing than clear, let's move on.

The last law that I want to mention is the Law of the Excluded Middle. This is another one that is easily misapplied because one has to be careful when it is appropriate to use it. This law somewhat combines the previous two by saying that "Any proposition, P, is either true or not true." There simply is no other option.

An example of this would be, "I am 5' 11" tall." Well, I am either actually 5' 11" tall which would make the statement true, or I am not 5' 11" tall which would make the statement not true. Because of the Law of Non-Contradiction, I cannot be both. But, since all other options apart from me being 5' 11" tall would make the original statement not true, you can see that there are only two options available...true and not true.

These three laws make up a solid foundation upon which to build virtually every argument or piece of evidence I will write about here. It is the bedrock of the various claims and conclusions that will be made. And usually, whenever you find yourself in a discussion with someone who says something that you know is wrong but can't seem to put your finger on why...check their statements against other known facts using these three laws and you will most likely find what is wrong with their arguments.

For more on the laws of logic:

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