The 3 Laws of Logic, Lickety Split

by N.P. Sala

In the previous post, I gave a brief overview of the history of knowledge (otherwise known as epistemology) and argued that humanity has slowly given up essential tools to assessing reality. During the section devoted to ancient realists, I mentioned the three laws of logic as they pertained to how realists viewed the world. In this post I would like to go a little further with these laws by providing definitions as well as some practical examples of how they work.

These laws, originally presented in Aristotle’s Posterior Analytics, are as follows:[1]

The Law of Identity

Definition: A is identical to itself and different from other things.

This idea may seem too commonsensical for anyone to bother postulating it as a formal law of logic, but do not discount its simplicity. Being aware of the Law of Identity can actually save your life. Imagine waking up in the morning and stumbling into your bathroom where you open up your medicine cabinet and see two bottles of pills in tablet form. One says “Tylenol” and the other says “Arsenic”. The Law of Identity states that Tylenol is Tylenol

CLICK HERE for Amazon Kindle deals in Christian Apologetics: Over 100 titles from 99 cents to $5.99!

and cannot be anything other than Tylenol. The same is true for the bottle of arsenic. So we could say, then, that a person is not justified in swallowing a couple of tablets of arsenic while pretending that it is identical to Tylenol. As an aside, the Law of Identity really becomes useful when figuring out whether the mind and the brain are identical. For my thoughts on that issue, click here.

The Law of Noncontradiction

Definition: A cannot be both true and false in the same sense at the same time.

If I were to tell you that my car was a black Camaro, it would be impossible for my car to be a black Camaro and not be a black Camaro at the same time. Pretty simple, right? This law is helpful in discussions about the nature of truth. For example, when disagreeing with others some people like to say, “What’s true for you is not true for me.” Unless the conversation is about something subjective (like favorite ice cream flavor) the Law of Noncontradiction reveals that statement to be incoherent. For example, if I were to tell you that the entire world we experience is an illusion (which is a typical Hindu belief), then the world cannot both be an illusion and not an illusion at the same time. Likewise, if I were to tell you that there is no such thing as a supernatural aspect to reality (which is a typical materialist/Atheistic belief), then my statement could not be true on Wednesday and false on Sunday. It is either all true or all false…


The 3 Laws of Logic, Lickety Split | A Clear Lens