Formal Fallacy Handbook

Formal fallacies are mistakes in an argument’s logical structure. They’re fallacies because the conclusion doesn’t logically follow from the premises. Unlike informal fallacies, formal fallacies don’t depend on context or subject matter: you can spot them even after translating the argument into symbols.

Note: This handbook includes many example arguments. In some, the premises are true; in others, they’re false. The correctness of premises doesn’t affect whether the argument is valid or invalid.

Get a free printable version of this handbook here.

Want to introduce your teens to formal logic? Check out Critikid's interactive course, Logic for Teens.

Courses

Fallacy Detectors

Ages 8–12

Develop the skills to tackle logical fallacies through a series of 10 science-fiction videos with activities. Recommended for ages 8 and up.

US$15

Social Media Simulator

Ages 9+

Teach your kids to spot misinformation and manipulation in a safe and controlled environment before they face the real thing. Recommended for ages 9 and up.

US$15

A Statistical Odyssey

Ages 13+

Learn about common mistakes in data analysis with an interactive space adventure. Recommended for ages 12 and up.

US$15

Logic for Teens

Ages 13+

Learn how to make sense of complicated arguments with 14 video lessons and activities. Recommended for ages 13 and up.

US$15

Emotional Intelligence

Ages 5–7

Learn to recognize, understand, and manage your emotions. Designed by child psychologist Ronald Crouch, Ph.D. Recommended for ages 5 to 7.

US$10

Worksheets

Logical Fallacies Worksheets and Lesson Plans

Ages 8–12

Teach your grades 3-7 students about ten common logical fallacies with these engaging and easy-to-use lesson plans and worksheets.

US$10

Symbolic Logic Worksheets

Ages 13+

Worksheets covering the basics of symbolic logic for children ages 13 and up.

US$5

Elementary School Worksheets and Lesson Plans

Ages 7–10

These lesson plans and worksheets teach students in grades 2-5 about superstitions, different perspectives, facts and opinions, the false dilemma fallacy, and probability.

US$10

Middle School Worksheets and Lesson Plans

Ages 10–13

These lesson plans and worksheets teach students in grades 5-8 about false memories, confirmation bias, Occam’s razor, the strawman fallacy, and pareidolia.

US$10

High School Worksheets and Lesson Plans

Ages 13+

These lesson plans and worksheets teach students in grades 8-12 about critical thinking, the appeal to nature fallacy, correlation versus causation, the placebo effect, and weasel words.

US$10