Errors in Reasoning: Faulty Logic

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SWBAT write examples of opinions with errors in reasoning about a given topic.

Big Idea

Students use critical thinking skills to detect faulty logic in arguments. Non-examples help students learn, too!

Types of Faulty Logic

20 minutes

In order to teach the Common Core writing standards of using reasoning to support opinions, I guide students to explore faulty logic examples in this unit.  Faulty logic is an argument that lacks validity. It is sometimes referred to as paradoxical reasoning because it is illogical, absurd, or contradictory.  Not only will they need to recognize faulty logic so as to avoid using it in their own opinion writing, later they will also be expected to assess reasoning provided by the author and determine if the evidence is based on fallacious reasoning as they enter middle school and high school in preparation for research in their careers or college. Students need to build on prior knowledge to get to that point.  Starting to introduce errors in logic in the primary grades gives students the foundational knowledge needed for this critical reasoning later on.

Although the concept of faulty logic and errors in reasoning is not often taught until later grades, I decided to present my gifted, high achieving class with this challenge.  It is an experiment of sorts for my class consisting of students who are out-of-the-box thinkers. The tricky part is teaching students through non-examples. This non-traditional route of teaching shows students what not to do instead of what to do.  Students use critical thinking skills as they analyze the irrationality of their writing. This activity is a demonstration of the old adage "Learn from your mistakes." Indeed, mistakes provide opportunities for learning.

I introduce students to six types of faulty logic via my Errors in Reasoning: Faulty Logic Introductory Flip Chart. We begin with a discussion about the accuracy of text and digital sources.  I asked students to recall some commercials they had seen in the past.  I scaffold on their prior knowledge, by asking them to label their commercial either fiction (if it seems inaccurate) or nonfiction (if it seems valid).  Then, we discuss reasons for their selection. 

I remind students of past experiences with research, when they find two conflicting sources.  How do we know if what we are reading is true?  How do we check?  What are some types of inaccuracies or "Faulty Logic"?  One student shared that after viewing the flipchart and participating in our discussion, that faulty logic means something doesn't make sense.  Students need to be aware of types of fallacies and persuasive techniques, such as the ones identified on the flipchart, in order to identify misnomers and improve their own ability to use logic in an argument.  Introducing students to these persuasive techniques prepares them with the knowledge to identify inaccuracies, judge credibility, and strengthen their opinion writing abilities.

Identifying Examples

20 minutes

Students are divided into cooperative groups of four to six members each.  We review the flip chart on Cooperative Groups norms, roles, rules

I give each cooperative group two samples of fallacies.  We discuss fallacies that are related to propaganda.  I explan to students that propaganda is biased information because it only tells people one side of the story.  We analyze and discuss some Errors in Reasoning and Propaganda Information.  The groups are to discuss the characteristics of their samples, using the definitions from the flipchart (I give each group a hard copy of the Errors in Reasoning Sample for reference).  Students have lively discussions coming up with example for their definitions. Ultimately, each team will produce one example.

The Results

20 minutes

Students from each team present their findings.  As each team discuss the identity of their false logic for their sample, they also elaborated on how their team collectively decided on their selection.  The audience also gets input and shares whether they agree or disagree with the team's findings and explain their reasoning.  This activity was an effective way for students to interact with one another to get clarification and elaboration on this topic, as supported by Common Core speaking and listening standards.

 Students shared innovative ideas such as Card Stacking Wow Cup Sample, Circular Reasoning student Sample, false cause student sample, and False Causality sample.  Presentations indicated student understanding of their assigned tasks: Cardstacking Student Oral Presentation.