what is “logic”?

There are a great number of ways to define logic, for there are a great number of philosophers who have a great variety of theories and opinions. I won’t pretend to create an authoritative dissertation on the matter, no, instead, I’ll present what I believe to be the “minimal conception,” that is, what it must at least be. It is then, sufficient to be applied in most circumstances, particularly in a discussion (informal or otherwise).

This article is greatly inspired by the book Come, Let Us Reason1, by Dr. Norman Geisler.

It is the function of the wise man to know order. – Aristotle

Logic isn’t really so tough. In fact, it’s one of the simplest things to use because you use it all the time, though you may not realize it.

sugarWhen you are at a supermarket and one brand of sugar is 3 cents per ounce, but another is 39 cents per lb. It it doesn’t take long for you to pull out your calculator. You do that because you recognize that those ounces and pounds have to be put in the same category to be compared.

That’s logic. You use logic to do most everything. When you decide to take a shower after you work out instead of before, you don’t necessarily go through all the formal steps it takes to reach that conclusion validly, but your decision rests on logic nonetheless.

Logic really means putting your thoughts in order.

So lets see how order works…

“Order” is the key word. It applies to all kinds of different disciplines. In nature, there is an order that reason discovers but does not produce. The patterns of quartz crystals, regularity of natural laws, movements of the planets, complex information in a single strand of DNA – they all show us an order that we can see but that we did nothing to put there, just as you are reading this post, but did not put the words here.

In art however, we do produce order. The artist imposes order on the things around him. He crafts the lines he wants to see, bends steel to suit his purpose, arranges the rhythms, the melodies, the harmonies to express a certain feeling. Art is created by a person imposing order on the things of the external world.

“Logic is the anatomy of thought” – John Locke

In philosophical thinking there is order also. Ethical order is order that reason produces in acts of the will. In other words, it is the ordering of our thoughts about the right and wrong of the things we choose. Whenever we ask a question about what we ought to do, we are ordering our choices by an ethical standard. That order tells us what we really think is good. It shows us what our values really are. Should I lie to save twenty bucks? Should I help the lady stranded on the freeway, or hurry home to watch football? How we answer depends on an ethical order that we produce about the choices we make. The best system of ethics is the one that best expresses the way things ought to be, or, what really is good and valuable.

logicThe order of logic is very similar  It, too, is an ordering that we produce, but it is concerned with ordering our thoughts. Logic is reason looking at itself to see how good reason works. It studies the methods that we use to analyze information and draw valid conclusions. It puts all of these methods into an order that gives us the right way to draw conclusions. The best system of logic is one that is best suited to drawing proper conclusions from the premises.

To state this as a formal definition: Logic is the study of right reason or valid inferences and the attending fallacies, formal and informal.

Let’s break it up…

Logic is the study of right reason. . . .  That is the main point. Logic is a study, an ordering, of how to think rightly, or how to find truth. ie…logic is a way to think so that we come to correct conclusions..

. . . or valid inferences. . . . That means implications. Part of studying logic is recognizing when A implies B and when it does not. There are clear-cut rules to help us with this.

. . . and the attending fallacies, formal and informal. A fallacy is a mistake. Sometimes we make mistakes in the way we set up our thinking, or by using an implication that is not true. These are “formal fallacies”, because they have to do w/ the form of the argument (more in a future post). Other times the mistakes are in the meanings of the terms we use. They might be unclear or misleading. Or, they might just not have anything to do with the subject at hand. Mistakes like these are “informal fallacies”. Knowing the kinds of mistakes we can make helps us to avoid them.

Logic is reason looking at itself to see how good reason works. – Dr. Norman Geisler

If we put all of our paraphrases together, we get a simplified definition: Logic is a way to think so that we can come to correct conclusions by understanding implications and the mistakes people often make in thinking.

So regardless of the environment, circumstances, entities involved…logic is unchanging. While the variables may change, the way in that variables are determined to be true, untrue, valid or invalid do not change. Logic is is after all, putting our thoughts in order.


1.  Geisler, Norman,  Come, Let Us Reason, 1990

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