(original post 16 Oct 2019)
I realize this is not everyone’s favorite topic, however some points must be made: Logic is unavoidable. Anytime someone makes a statement, or asks a question, logic is utilized. When a person makes a claim, logic (good or bad) is employed. When a question is asked, a truthful response is expected, and logic is used to reason to an answer. This topic will be addressed in two separate posts. This post will focus on the laws of logic concerning thought. The next post will dive into some of the logical fallacies people use and need to stay away from.
Logic has several definitions:
- a science that deals with the principles and criteria of validity of inference and demonstration : the science of the formal principles of reasoning
- a particular mode of reasoning viewed as valid or faulty
- interrelation or sequence of facts or events when seen as inevitable or predictable[1]
It is the 2nd and 3rd definitions that I will focus on today. In order to do so, we need to understand some of the laws of logic as well as some of the fallacies. Following laws of logic should bring one to true and valid conclusions, however that depends on the truthfulness and validity of the premises used to reason to that conclusion. Additionally, if one employs (intentionally or unintentionally) a logical fallacy, the validity of that person’s argument is at risk.
So, what are some of the laws of logic. For this we will look at laws of thought, of which there are three which people recognize: principle of identity, law of non-contradiction, and law of the excluded middle.
- Principle of Identity—“asserts that a thing is identical with itself (x=x)[2].” As J.P. Mooreland states, “The law of identity says that if a statement such as ‘It is raining’ is true, then the statement is true. More generally, it says that the statement P is the same thing as itself and it’s different from everything else. Applied to all realty, the law of identity says that everything is itself and not something else.[3]”
- Law of Non-contradiction—a statement cannot both be true and not true in the same sense / context. For example, “It’s snowing outside” is not the same as “It’s not snowing outside” and both statements cannot be true at the same time. It’s either snowing OR it is not snowing.
- Law of the Excluded Middle—asserts that a statement is either true OR false; there is no third option. “It is raining / snowing” OR “it is no raining / snowing”—there is no other option; either this OR that.
When discussing or debating with someone, these three laws should be in our minds as they play vital roles in the situation. This is where Greg Koukl’s Columbo tactic #1 may come into play. Speaking to a Mormon, they use many of the same words as Christians do (salvation, Jesus, heaven, etc) but with different meanings. The Mormon concept of salvation ≠ the Christian concept of salvation. In order to constructively move the conversation, we must understand the principle of identity because if we aren’t talking about the same thing, the conversation becomes nonsensical as we come to differing conclusions. Asking “what do you mean by that (salvation)?” will put us on the same footing to engage effectively OR give us pause to debate the terminology before moving forward.
The law of non-contradiction is a personal go-to regarding Christianity. All worldviews make truth claims. The concept of truth has exclusive characteristics to it. Theism claims that God exists, atheism claims God does not exist. God cannot both exist and not exist at the same time. Christians claim Jesus is the Messiah; Muslims and Jews claim Jesus wasn’t the Messiah. These differing truth claims prove that religions are not all the same! All of them could be false, but not all of them can be true. When looking at John 14:6, Jesus declares Himself as “the way, the truth, and the life…no one comes unto the Father but by Me.” Jesus made a definitive truth claim, which if it is true, ALL other religions are false. If Jesus was lying, Christianity is false; Jesus can’t be the embodiment of truth and tell lies—such contradiction is self-destructive.
Applying the law of the excluded middle to a prior example, Jesus is the Messiah OR Jesus is not the Messiah. There is no third option! There’s no blending of the two ideas to create a Jesus was “somewhat” the Messiah or “a partial” Messiah. The law of the excluded middle establishes an all-or-nothing situation; “yes” or “no” and never “maybe.”
As a final point on this, logic is an immaterial reality which eternally exists. That is, logic is not something man created through evolution of consciousness, intelligence, and reasoning. Logic deals with truth and truth predates the existence of man. Logic is something man has discovered, not something we have invented. Example: in the history of the planet (Big Bang to formation of living creatures), evolutionists and Biblical creationists agree that there was a time when “man did not exist on earth.” That statement was true when man-did-not-exist-on-earth. That statement, its truthfulness, and logical reasoning to it as a conclusion is independent of a human mind. We merely acknowledge that the statement was true up to a point in earth’s history. When man did exist on earth, that statement no longer applied and to make such a claim would be to make a false one.
Logic is something we cannot escape. Every thought, whether internal, written, or vocalized, employs logic. We agree or disagree with statements based on a logical process which brings us to a conclusion. Granted, this is an ideal situation as most people don’t knowingly and intentionally employ logic to affirm or destroy a person’s claims. Often we agree or disagree with a claim because of a number of factors / variables. However, we need to be more diligent to explore the validity of claims people make instead of taking things at face value and assuming the truthfulness of what is said. Many people use flawed logic. Many people employ logical fallacies. Many people simply regurgitate talking points without examining the validity of the argument. Let us not fall into that camp and take a little more time and effort to be confident in what we say and the reasons behind why we believe what we believe.
In Christ!
[1] https://www.merriam-webster.com/dictionary/logic
Way Truth Life Apologetics 
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