Truth: The Laws of Thought and Noncontradiction


The other day I started a new series here on Truth.  It’s a building-block style series where each post will assume you’ve read the previous.  If you haven’t done so, check out my first one, here.

Last post, we established the societal views between absolute truth and subjective truth.  We looked at moral absolutism vs. moral relativism and saw that Absolute truth and moral absolutism actually win the day in logic and philosophy because truth is unchangeable, regardless of feelings or personal convictions.

In this post, I want to take that to the next step and look at what philosophy and logic calls the Law of Noncontradiction.

What is the Law of Noncontradiction?

It’s one of the Three Traditional Laws of Thought.

The laws of thought are fundamental axiomatic rules upon which rational discourse itself is often considered to be based. The formulation and clarification of such rules have a long tradition in the history of philosophy and logic. Generally they are taken as laws that guide and underlie everyone’s thinking, thoughts, expressions, discussions, etc.

The three Laws of to Thought are:

  • The law of identity: ‘Whatever is, is.’

    Regarding this law, Aristotle wrote:

    First then this at least is obviously true, that the word “be” or “not be” has a definite meaning, so that not everything will be “so and not so”. Again, if “man” has one meaning, let this be “two-footed animal”; by having one meaning I understand this:—if “man” means “X”, then if A is a man “X” will be what “being a man” means for him. (It makes no difference even if one were to say a word has several meanings, if only they are limited in number; for to each definition there might be assigned a different word. For instance, we might say that “man” has not one meaning but several, one of which would have one definition, viz. “two-footed animal”, while there might be also several other definitions if only they were limited in number; for a peculiar name might be assigned to each of the definitions. If, however, they were not limited but one were to say that the word has an infinite number of meanings, obviously reasoning would be impossible; for not to have one meaning is to have no meaning, and if words have no meaning our reasoning with one another, and indeed with ourselves, has been annihilated; for it is impossible to think of anything if we do not think of one thing; but if this is possible, one name might be assigned to this thing.) — Aristotle, Metaphysics, Book IV, Part 4 (translated by W.D. Ross)

  • The law of noncontradiction:  Nothing can both be and not be.

    In other words: “two or more contradictory statements cannot both be true in the same sense at the same time”. In the words of Aristotle, that “one cannot say of something that it is and that it is not in the same respect and at the same time”. Regarding this law, Aristotle writes:

    It is impossible, then, that “being a man” should mean precisely not being a man, if “man” not only signifies something about one subject but also has one significance … And it will not be possible to be and not to be the same thing, except in virtue of an ambiguity, just as if one whom we call “man”, and others were to call “not-man”; but the point in question is not this, whether the same thing can at the same time be and not be a man in name, but whether it can be in fact. — Aristotle, Metaphysics, Book IV, Part 4 (translated by W.D. Ross)

  • The law of the excluded middle: Everything must either be or not be.’But on the other hand there cannot be an intermediate between contradictories, but of one subject we must either affirm or deny any one predicate. This is clear, in the first place, if we define what the true and the false are. To say of what is that it is not, or of what is not that it is, is false, while to say of what is that it is, and of what is not that it is not, is true; so that he who says of anything that it is, or that it is not, will say either what is true or what is false            — Aristotle, Metaphysics, Book IV, Part 7 (translated by W.D. Ross)

According to the 1999 Cambridge Dictionary of Philosophy, laws of thought are laws by which or in accordance with which valid thought proceeds, or that justify valid inference, or to which all valid deduction is reducible. Laws of thought are rules that apply without exception to any subject matter of thought, etc.

It should be noted that this was subscribed to and affirmed by Plato, Indian thinkers, Buddha, John Locke, and a myriad of others that are giants of philosophy.

So if we boil it all down, through ancient logic and confirmation by modern scholars, something cannot be and not be at the same time.  I cannot say that a red car is parked in front of my house and also say a red car is NOT parked in front of my house.

So let’s talk noncontradiction.

In order for something to be contradictory, it must violate the law of noncontradiction. This law states that A cannot be both A (what it is) and non-A (what it is not) at the same time and in the same relationship. In other words, you have contradicted yourself if you affirm and deny the same statement. For example, if I say that the moon is made entirely of cheese but then also say that the moon is not made entirely of cheese, I have contradicted myself.

In our world today,  the law of noncontradiction is often viewed as  Western construct. A lot of folks in our time believe that Western “Either-Or” logic is too arrogant, dogmatic, and exclusive…and so they opt for a dialectic system of logic, or a “both and” line of thought.

In the alternative facts culture and post-truth politics of 2017, these laws are important to remember.  When we subscribe to a “both/and” logic, what we are saying is “things can be whatever they will be, as long as they be to me.”  It’s often an emotional appeal devoid of, or at least severely pared down with any facts.  If we are to believe that, than absolute truth and moral absolutism are dead.

However, the law of noncontradiction, propped up with the other two Laws of Thought,  will always prevail.  Why? Because they are not rooted in emotional conjecture or subjective opinion.  They are grounded in reality – that is, in what actually is – held up by observable, provable, unchanging principles.

Why does this matter?  Well, because these logical laws rooted in reality prove that there is absolute truth and morality is not relative.  Therefore, when someone presents something to you, it is YOUR job to make sure that it is actually truth.  Do not be quick to replace truth with opinion, conjecture, or conviction.  

At the end of the day, truth will be proven true, regardless of efforts to spin, bend, eradicate, or change it.  As Jesus says:

But wisdom is proved right by her deeds. (Matthew 11:19b, NIV)

And also,

31 To the Jews who had believed him, Jesus said, “If you hold to my teaching, you are really my disciples. 32 Then you will know the truth, and the truth will set you free. (John 8:31, NIV)

So then, we can conclude, there is absolute truth.  If Jesus makes these claims, we also see they are diametrically opposed to many other truth claims in our world.  Perhaps non so strong as the one made at the Last Supper:

“I am the way and the truth and the life. No one comes to the Father except through me. (John 14:6).

How does all this apply?  Why do I close with that statement?  Why all the philosophy?  We’ll get to that in the next post.

I love you.  God loves you more!


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