Why Christians Should Study Logic

With Suggested Texts for Learning

And yet the validity of logical sequences is not a thing devised by men, but is observed and noted by them that they may be able to learn and teach it; for it exists eternally in the reason of things, and has its origins with God.

- St. Augustine (On Christian Doctrine)

Learning to reason well is an act of worship because studying logic is the practice of training our minds to see and approve of what is true while also rejecting what is false and not worthy of belief. The word logic is derived from the Greek word λόγος. This word, as you may know, is in John 1:1 when the Scriptures tell us, “In the beginning was the Word and the Word was with God and the Word was God.” Then later in verse 14 we are told, “and the Word was made flesh and dwelt among us, and we have seen his glory, glory as of the only Son from the Father, full of grace and truth.” The Word (i.e. λόγος) is the Son, the Christ, Jesus.

I am not here to take you on some weird trip and try to convince you to worship logic as God, no sir, but there is a meaningful connection that is worth seeing here. The Son of God, Jesus of Nazareth, is the λόγος. The fact that this word can be reasonably translated as “logic” is not nothing. What is meant by calling the Son “the Word” other than that he is the rational communication of God to man? It is by the Word made flesh that we may see, hear, and know God himself. Jesus is God’s self disclosure, the rational communication of himself, to us. In other words, God speaks to us in ways that we might understand him, ways that make sense, “For God is not a God of confusion but of peace.” (1 Corinthian 14:33)

Ultimately the purpose of learning Logic as a discipline is to know truth and separate it from falsehood, to gain wisdom and understanding which starts with “the fear of the Lord” (Proverbs 1:7; 9:10). Jesus tells us that he is himself “the Truth” (John 14:6) and that God’s word “is truth” (John 17:17). Pilate once asked “Quid est veritas?” or “What is truth?” while literally staring truth in the face while he asked!

God has communicated to us through his word (the Scriptures) and through the Word (Jesus, his Son) and all of it requires reason to rightly receive his message. The Scripture is full of propositional statements, reasoned arguments, intentionally given evidence, and even displays of illogic (for indeed the Bible records inerrantly and faithfully the historical folly of foolish men as well as God’s own faultless words and deeds by his prophets, apostles, and Son).

To faithfully interpret the Bible we must be able to follow extended lines of argument. 1 Corinthians is a great example of extended arguments in Scripture. For instance, 1 Corinthians chapters 8, 9, and 10 present one argument about how Christians should think about food offered to idols and the ramification of those same principles on other areas of Christian living. 1 Corinthians chapters 12, 13, and 14 present one argument about what the Spiritual Gifts are, what they are for, and how, when, and in what way they should operate in private life and corporate worship. The failure to see the continuity of arguments in Scripture or to understand the premises of Paul’s arguments, the various conclusions he draws and how those same conclusions become new premises for further arguments, etc., will result in a misunderstanding of what God is telling his people in his word. Indeed, misunderstanding is rampant because too many Christians (even seminary trained ministers) fail to see the arguments in their whole and in their parts. In fact, most seminaries don’t teach logic (to their shame and to the detriment of the men they are training and the local churches that will call them as shepherds).

Logic also brings believers comfort when they reason from what the Scripture says to greater assurance of their salvation. Take for instance when the apostle Paul writes, “But if anyone loves God, he is known by God.” (1 Corinthians 8:3) The believer, who does in fact love God, may reason thus:

1. If anyone loves God, he is known by God.

2. I love God.

3. God knows me.

This is a modus ponens (a valid form of a mixed hypothetical syllogism). If the premises are true then the conclusion is guaranteed by the laws of logic to also be true. How comforting to draw from God’s word such assurance!? This is but a small example but such work can be done all over the Scriptures (not to mention other forms of literature) to draw out truth by inference. Sometimes that truth is comforting, often it is convicting, but always it is there for the reader to know and be changed by for the better if only he or she knows how to reason it out.

The Scriptures tell believers that we are to be “wise as serpents and innocent as doves.” (Matthew 10:16) We are not to be taken in by every claim, to believe every rumor, nor “tossed to and fro by the waves and carried about by every wind of doctrine, by human cunning, by craftiness in deceitful schemes.” (Ephesians 4:14) God invites us, “Come now, let us reason together, says the Lord” (Isaiah 1:18). Paul, likewise, “reasoned in the synagogue with the Jews and the devout persons, and in the marketplace every day with those who happened to be there.” (Acts 17:17) Indeed he “tried to persuade Jews and Greeks.” (Acts 18:4) All of this requires logic, good logic.

Everyone reasons, but few people reason well without instruction on the principles and methods of proper reasoning. While it is true that the laws of logic are built into the fabric of the universe, and they are woven in because they are a reflection of the perfect and changeless mind of the eternal God¹ it does not follow that people are going to reason well automatically. We all make use of the laws of logic all the time without thinking about them (indeed communication is only possible because the laws of logic exist) but we are greatly helped by actually thinking about them! We become clearer thinkers, clearer communicators, greater ambassadors of truth, we let go of falsehoods, and become more consistent in our own beliefs when we learn how to use logic well.

Lord willing, in the not too distant future, I intend to start a series of posts to teach the foundations and principles of logic and argument making. In the meantime I want to point you towards some great resources you can pick up now if you’d like.

Here are the logic textbooks which I know best, have used substantially, and can recommend without reservation:

1. Introductory Logic, by James Nance

2. Intermediate Logic, by James Nance

3. Come, Let Us Reason, by Geisler and Brooks

4. Socratic Logic, by Peter Kreeft

I use the James Nance texts as my primary teaching textbooks for 7th and 8th grade while bringing in elements of Come Let Us Reason to teach Inductive Logic. I am planning to use much of the Socratic Logic text for 9th grade Logic while also reading some primary source material (see below). Throughout 7th-9th grade I add some of my own exercises beyond what is in these texts and I am working to develop material to help students master the skills of argument building and recognizing and interacting with arguments found in the literature they are reading in all of their classes. Again, I hope to post some of this material here on Study the Great Books in the near future.

If you want to go to the primary sources on logic as opposed to textbooks, which I heartily approve of, then here are just a few worth your time (there are many others):

1. Aristotle’s Organon

   1. Categories

   2. On Interpretation

   3. Prior Analytics

   4. Posterior Analytics

   5. Topics

   6. On Sophistical Refutations

2. The Metalogicon by John of Salisbury

3. Francis Bacon’s New Organon

Here are some further Logic Texts which I have interacted with some but have not studied or taught through thoroughly, which are nevertheless worth your time if you are looking for even more material to play with:

1. Traditional Logic 1 & Traditional Logic 2, by Martin Cothran

2. Logic: The Right Use of Reason in the Inquiry After Truth, by Isaac Watts

3. Introducing Logic and Critical Thinking, by T. Ryan Byerly

4. The Game of Logic, by Charles Dodgson (i.e. Lewis Carroll of Alice in Wonderland fame)

1. Logic is not made by man, it is discovered. The laws of Logic, unlike the laws of physics, are immutable. God could have made the laws of physics differently had he desired, but the laws of logic actually correspond with God’s own changeless being. Such being the case, the laws of Logic can be nothing other than what they are.