Fallacies in Comics

Comic strips are a great place to find examples of informal fallacies. It seems that we tend to find improper reasoning funny. In the “Peanuts” comic strip, Lucy is ad baculum incarnate. Below is the entire strip:


Note that the fallacy is not really made by Lucy making the threat, but by Charlie Brown, who is convinced by her “argument.”

Here is another example, where Lucy persuades Linus to memorize his lines using “five good reasons”:

Here is an example of Calvin falling for his father’s ipse dixit :

Related image

For the ad populum, consider this classic bandwagon example from “Zits”:


There are many more examples of informal fallacies in the funnies. See what you can find!


Logic with James B Nance

Audit Intermediate Logic

Would you like to be a fly on the wall in my logic class? Want to improve your understanding and/or teaching of logic by watching me teach and interact with my students, discussing the lesson after the class, and having the recorded class sessions available? If so, click HERE to audit Intermediate Logic for the 2017 school year!

What’s included for Auditors? First, you have access to all the live classes. During the discussion, you will not be called upon as I do with my regular students. You are free to watch in the background by muting your mic and camera, but you also have the option of appearing to ask a question or make a comment if you’d like.

After the regular class time has ended, students leave the virtual classroom while auditors are invited to stick around for a few minutes to ask “Teacher Questions”! This is when you would have me all to yourselves as teachers. Turn on your webcams and mics, and discuss the lesson, teaching logic in general, or whatever questions you might have.

We will meet together live for online recitations Monday/Thursday from 8:00-9:30 AM (PST), or Tuesday/Friday from 8:00-9:30 AM (PST). The spring semester starts January 5/6, 2017, and goes to May 18/19, with a Winter Break in mid-February and an Easter Break in mid-April.

I hope to see you there!


In Defense of the Winter Soldier

As I teach for the first time through Fitting Words: Classical Rhetoric for the Christian Student, I am pleased with what my students are producing.

We have been learning about forensic (or judicial) oratory, including the definition of wrongdoing, the elements of proving wrong, the state of mind of wrongdoers, non-technical modes of persuasion, and more. The most recent assignment was this:


Here is the forensic speech of one of my students, Daniel Seifert, defending Bucky Barnes (from “Captain America: The Winter Soldier”) of the alleged murder of Tony Stark’s parents and others.


Help With Establishing Conclusions

One of the most practical lessons in Introductory Logic is Lesson 32, “Establishing Conclusions.” Here you are no longer analyzing someone else’s arguments; you are now writing your own. The hardest part of this lesson is developing an argument for a conclusion while being allowed to use any valid form. In the video for this lesson, I encourage you to find a middle term that connects to the major and minor terms in the conclusion. Let me suggest another way to continue this process.

If you understood hypothetical syllogisms well in the lesson prior, you may use them to help you develop a valid argument. For example, in Exercise 35, question 2, you are asked to establish this conclusion (straight out of Calvin and Hobbes):


Ask yourself why bats aren’t bugs. You might say, “Because mammals are not bugs.” Turn that into a hypothetical statement, and complete the modus ponens: Continue reading Help With Establishing Conclusions


Exercise 30, problem 4: Is my answer correct?

Mr. Nance,

As I am reviewing Exercise 30, I am confused  if my answer works , since its different from the original answer. I put:

No logic is a tangible study
No chemistry is logic
∴ All chemistry is a tangible study

As opposed to the answer key:

All non-logic sciences are tangible studies
All chemistry is a non-logic science
∴  All chemistry is a tangible study

Which one is right? Continue reading Exercise 30, problem 4: Is my answer correct?


Gospel Enthymemes

Arguments in which one statement is left assumed are called enthymemes. Most logical arguments encountered in daily life are enthymemes. We can use the tools of logic to determine the assumption being made in an enthymeme.

Let’s examine three enthymemes in the Bible, all on the topic of Gospel salvation. Continue reading Gospel Enthymemes


Exclusive help

Unit 4: Arguments in Normal English in my Introductory Logic text is a difficult section, primarily because of the ambiguities within English. But if we want to be able to apply the tools for analyzing syllogisms to everyday arguments, it is essential that we understand it.

One of the more difficult parts of this difficult section ideals with translating exclusive statements into categorical form. Exclusives are statements that exclude all or part of the predicate of the subject, statements that use words like only, unless, except. Let me give some suggestions that may help. Continue reading Exclusive help


Alternate Answers for Exercise 27

I have received several inquiries regarding other possible solutions to the syllogism translations in Introductory Logic Exercise 27. Though the Teacher’s Edition offers only one solution per problem, there are in fact many possible correct answers to each question.

Here is one more reasonable possibility for each: Continue reading Alternate Answers for Exercise 27


Some Uses of Immediate Inference in Scripture

Logic students sometimes struggle with understanding and remembering immediate inferences. The more opportunities they have to see them used, the more likely they are to grasp them. Consequently, I want to give some examples of immediate inferences used in the Bible. Two equivalent immediate inferences for categorical statements are obverse and contrapositive. Continue reading Some Uses of Immediate Inference in Scripture