The study of logic doesn’t teach you to think—people do that intuitively and naturally. Rather instruction in logic teaches you to order your thinking.
Logic is typically defined as “the principles of correct reasoning.” Mastery of these principles helps a person to consistently order their thinking so they can arrive at truthful, rational conclusions. Known as the “father of logic,” famous Greek philosopher Aristotle (384-322 BC) was the first to systematize the principles of logic. He referred to logic as a “tool” or “instrument” that helps one arrive at truth.
Logic is used to prove (or verify) things through the use of arguments. (By arguments, I don’t mean verbal fights.) An argument consists of two essential parts: (1) a claim (or conclusion), and (2) support for the claim (or premises) in the form of reasons, evidence, or facts. A good argument (sound or cogent) requires that the premises genuinely support the conclusion—a necessary connection called an inferential relationship must exist. A breach in this relationship results in a breakdown or failure of the argument to prove the conclusion. Fallacies (errors in reasoning) describe various types of breakdowns in the premise(s)-conclusion relationship.
ARGUMENT = CLAIM + SUPPORT
Since the conclusion of an argument is only as good as the premises that support it, it’s critical that the premises genuinely backup the central claim being made. I came up with the following acrostic to serve as a guideline to help keep a person’s reasoning on the logical
- All premises must be factually true or intellectually acceptable. In some cases premises are generally accepted as true rather than actually demonstrated to be so.
Relevant support: The premises must be connected and readily applicable to the conclusion. Many informal fallacies fall into the irrelevant premise category.
Adequate support: The premises must provide enough support—sufficient in number, kind, and weight—to justify the conclusion. Sometimes one premise is enough, but other arguments require numerous premises.
Clear support: The premises must possess clarity, thus avoiding vagueness, ambiguity, and grammatical error. Thinking and speech should form a unity.
Knowledgeable support: The premises must qualify as knowledge (justified, true belief), avoiding unwarranted presumption and vulnerability to possible counter evidence.
Paying careful heed to the principles of logic makes our arguments and viewpoints rational and ultimately persuasive. It behooves us as Christians to excel in our thinking. Sound reasoning not only helps remove obstacles to faith in Jesus Christ, but it also—especially when combined with a winsome spirit—exemplifies Christian virtue. Careful thinking brings honor and glory to our Creator and Lord (Romans 12:2).
Remember, a mind made in the direct image of an infinite and eternal God (Genesis 1:26-27) is all the more a terrible thing to waste!
For more about the importance of logic and critical thinking, see my book A World of Difference: Putting Christian Truth-Claims to the Worldview Test. For a great handbook in dealing with logical fallacies, see Attacking Faulty Reasoning: A Practical Guide to Fallacy-Free Arguments by T. Edward Damer.