One of the most important skills to master, particularly if you intend to share your faith with others, is how to form a logical argument. Though it might seem complicated, an argument in logic is really a very simple thing. To have an argument you must make a claim (called the conclusion) and provide support (called premises) for believing the claim to be true or correct. To have a good argument (sound or cogent) your premises must be (1) true; (2) relevant to your central claim; and (3) adequate to sufficiently support the conclusion.
When I give a talk or write an article that includes a logical argument, I consciously ask myself five questions. These questions serve as my “checklist” to ensure that I’m on the proper logical track. I refer to these questions as the “five Cs of logical persuasion.”
1. Clear: Is the claim that I’m defending sufficiently clear?
The claim or conclusion of my argument is what I am trying to prove or justify and, therefore, what I want people to accept. Thus, I try to be crystal clear in setting forth the important central claim.
2. Concise: Is my argument adequately concise?
Long-winded arguments often lose both focus and force. Therefore, I prefer to keep my arguments as succinct and crisp as possible. Stating an argument in its simplest form is often quite powerful.
3. Cogent: Is my argument well conceived and well evidenced—and, therefore, logically cogent?
Good arguments exhibit careful thought and logical structure. Proper support for the conclusion should be sufficient and logically relevant. A cogent argument reflects well-ordered thinking.
4. Consider: Have I considered the possible counter evidence?
Some evidence could serve to weaken or falsify an argument. Careful thinkers give consideration to their argument’s potential weaknesses. Anticipation of possible criticisms of an argument shows intellectual forethought and reflection.
5. Compelling: Have I used skillful language and powerful metaphors that can serve to compel the will of my listeners?
Persuasion often involves more than mere logical argument. Captivating rhetoric and imaginative stories can also serve to help induce the human will to conviction. It is important, however, that one’s rhetoric and narrative needs to remain consistent with the logical principles discussed above.
A great benefit of studying logic is that it serves to order a person’s thinking. Order helps protect a person from crooked or fallacious thinking. Asking the five C’s of persuasion helps ensure that valued order.
Logic is also a tool that can help people discover truth. And since truth is a sacred thing, logic is a valuable tool indeed.
Recommended Logic Resources:
T. Edward Damer, Attacking Faulty Reasoning (Belmont, CA: Wadsworth, 2001).
Patrick J. Hurley, A Concise Introduction to Logic (Belmont, CA: Wadsworth, 2003).
Kenneth Richard Samples, A World of Difference (Grand Rapids: Baker, 2007).
Reflections 
Nice post with good information. I appreciate the list of recommended resources, but at $91.63 and $141.67 I’ll have to wait until I get rich to afford these! 🙂
John:
Textbooks are indeed expensive these days. But my book is available at an inexpensive cost of $17.95 at the RTB webstore: http://shop.reasons.org/A-World-of-Difference-p/rb0701.htm
Excellent advice. The only thing I would add is this: before we present logical arguments we should spend a fair bit of time asking questions of the person we are dialoguing with in order to better understand them and their worldview. [Assuming we are dialoguing in person, of course; essays are a different kettle of fish.] Only then will we know which arguments will be most relevant to them, and what’s the best form of the argument to present. Assuming that part is taken care of, though, everything else you’ve written seems spot on! Thanks for the excellent summary.
Looks like I missed your comments all those years ago. Sorry.
Thank you for your thoughtful point. It is an important one.
Best regards.
Ken Samples
What a wonderful post! I completely agree! I took a philosophy course in college, and we spent a month on a short logic unit. Those weeks spent studying logic provided a basis for me to solve problems, keep emotion to a minimum in arguments, and plan for the future. This summer, my 9th grader had the opportunity to take a summer classical logic course. I was disappointed that there were only two students in the class. Our educational system would only strengthen if this were added to our curriculum!
maggiemurphy.wordpress.com
Maggie:
Logic is a unique class that can truly empower the student.
Best regards.
Try a Rulebook for Arguments – Anthony Weston
This gives nice ideas on how to present something pleasantly, but you can be clear, concise and so on and be completely illogical. Christians need to learn a bit about logical fallacies. One reason is so we’re not taken in by people who are manipulating us, another is to make sure we’re not begging the question, using circular reasoning, employing the genetic fallacy, using arbitrary assertions and so on.
Looks like I missed your comment a ways back. Sorry.
Thanks for your comments.
A couple points in response for your consideration:
1. Logic is ordered thought so being clear and concise helps guard against committing informal logical fallacies (like fallacies of ambiguity and presumption [i.e. amphiboly, circular reasoning]).
2. You can’t be cogent (point #3) and be illogical. Cogency has nothing to do with being pleasant instead it’s about the connectedness between premises and conclusion.
3. Detecting faulty reasoning (fallacies) is critical but it is learning what is wrong with an argument (negative). My logic check-list seeks to illustrate what is right with a cogent argument (positive).
Thanks.
Ken Samples
Thanks for the link.
Ken Samples