Table of Contents: Logic 101


(To find something more quickly, use Ctrl+F.)

General Topics: What’s an Argument? → Three Basic Types of Arguments → Learning to R.E.A.D. → A Code of Intellectual Conduct → The Qualities of Good Arguments → How to Have Fruitful Conversations (Part 1, Part 2)


General Topics: How to Reconstruct an Argument → Four Types of Terms → How to Define Terms → How to Raise an Argument → How to Outline an Argument

Deductive Logic: Necessary and Sufficient Conditions → Introduction to Logical Symbols → 8 Basic Rules of Logic → Conditional Proofs

Aristotelian (Categorical) Logic: Introduction to Aristotelian (or Categorical) Logic → Terms and Categorical Statements → Introduction to Syllogisms → Mood and Figure for Syllogisms → Enthymemes and Sorites → How to Reconstruct a Syllogism → How to Raise a Syllogism


Deductive Logic: Introduction to Truth Tables → 7 Ways to Use Truth Tables · DeMorgan’s Laws and Other Logically Equivalent Statements → Some Technical (But Important) Topics in Deductive Logic

Aristotelian (Categorical) Logic: Aristotle’s Six Rules → A Mnemonic Device for Valid Syllogisms → A List of Valid Syllogisms → Venn Diagram Analysis

Other Topics: Explanatory Criteria for Abductive Arguments


To Believe, or Not to Believe? → Arguing Forward and Arguing Backward → On Revisiting Arguments


General Topics: Rules for Denying Arguments → Constructing Dilemmas

Deductive Logic: Reductio ad Absurdum Arguments → Parodies and Counterexamples → The Role of Counter-Arguments

Aristotelian (Categorical) Logic: The Traditional Square of Opposition

Logical Fallacies


Structural Principle: Circular Reasoning → Denying the Antecedent and Affirming the Consequent → Improper Direct Inference → Undistributed Middle Term

Relevance Principle: The Genetic Fallacy → Appeal to Authority

Acceptability Principle: Begging the Question → Equivocation → Fallacy of Composition → Is-Ought Fallacy

Sufficiency Principle: The Post Hoc Fallacy → Gambler’s Fallacy

Rebuttal Principle: Shifting the Burden of Proof → Arguing Ad Hominem → Poisoning the Well → Attacking a Straw Man → Red Herring