David W. Agler

Critical Thinking

Critical thinking (also known as informal logic & practical reasoning) is the use of reason to distinguish good arguments from bad arguments in real-life situations. This ability includes an array of different skills, e.g. being able to identify arguments from non-arguments, determining what is relevant to a conclusion, and developing a vocabulary for talking about and evaluating arguments. While all of us can and do think critically, none of us are perfect reasoning machines. We often succumb to our biases when we should't, rely on the testimony of authorities who are not genuine authorities, or uncharitably cast our political or intellectual opponents as fools when their views are actually quite sophisticated. The primary purpose of this course is to help you develop the critically thinking skills you already possess. To achieve this, this course includes an analysis of language, inductive and deductive reasoning, and a discussion of how to evaluate arguments effectively in everyday situations. At the end of this course, you should be able to do all of the following and more:

(1) distinguish the functions of language and its capacity to express and influence meaning,
(2) identify, analyze, and evaluate a variety of different types of arguments (inductive and deductive),
(3) recognize common fallacies or errors in reasoning


Fall 2013
Spring 2013
Summer 2012


Supplementary Guide for Web Course

H0: Getting to Know You Exercise
H1: Introduction, Voir Dire, Two Kinds of Critical Thinking
H2: Argument Terminology
H3: The Ad Hominem Fallacy
H4: The Strawman Fallacy
H5: Identifying the Conclusion
H6: Relevant Reasons & The Red Herring Fallacy
H7: Diagramming Arguments
H8: Appealing to Ignorance
H9: Fallacies of Ambiguity
H10: Appeals to Authority
H11: Arguments by Analogy
H12: Slippery Slope Arguments
H12s: Fallacies of Vagueness
H13: Reasoning with Dichotomies
H14: The Golden Mean Fallacy
H15: Necessary and Sufficient Conditions
H16: Scientific and Causal Reasoning
H17: Eyewitness Testimony
H18: Evaluating Statistics
H19: Reasoning with Probabilities
H20: Circularity, Begging the Question, and Evidence-Proofing
H21: Application #1: Reasoning about Legal Topics
H22: Application #2: Reasoning about Moral Topics
H23: Application #3: Reasoning about Scientific Topics
H24: Application #4: Reasoning about Religious Topics
H25: Application #5: Using Critical Thinking to Write Effectively

Teaching Resources

On Critical Thinking

The Critical Thinking Community
Critical Thinker Academy

On Writing Essays

A Basic Guide to Writing Essays
Ten Steps to Writing an Essay