An Online Resource for Logic Teachers and Students of Logic

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These slides are supplemental material on topics in the book Introduction to Logic

Fundamental Concepts of Logic

For more information on these topics, see chapters 1-6 in Introduction to Logic

Introduction to Logic

A concise introduction to the discipline and some resources for further study.

What is an Argument?

One of the fundamentals of logic and an important starting point.

Supplement - The Argument Clinic

Deductive and Inductive Arguments

Arguments of necessity and impossibility, and probability.

Deductive and Deductively Valid Distinguished

The conclusion must follow from the premises in the right way.

What is Validity?

Hint: It's about the structure not truth value.

More on Validity

Digging deeper on the concept of validity.

Inductive Strength

The stronger the argument, the more probable is the conclusion.


How statements in logic relate to each other and how truth plays a role.

Overview of the Fundamentals of Logic

An overview of key concepts in the Fundamentals of Logic

Categorical Logic

For more information on these topics, see chapters 7-9 in Introduction to Logic

Elements of a Categorical Sentence

An introduction to categorical logic -- the logical system of the Ancient Greeks.

Elements of a Categorical Syllogism

Categorical logic applied to arguments.

Venn: Testing an Immediate Inference

Using a Venn Diagram to test whether a conclusion follows from just one premise.

Venn: Testing a Syllogism

Using a Venn Diagram to determine whether a syllogism is valid.

Truth-Functional Logic

For more information on these topics, see chapters 10-22 in  Introduction to Logic

What is a Truth-functional Compound Sentence?

Identifying Truth-functional Argument Forms

Translation from English to TL Part 1

Translating from English to TL Part 2

Calculating the Truth Value of a Sentence

Elementary Truth Tables

Inference Rules: The Second Four

Replacement Rules 1

Replacement Rules 2

Replacement Rules 3

Let's Do an Indirect Proof

Let's Do a Conditional Proof

Let's Do a Premise-free Proof

Predicate Logic

For more information on these topics, see chapters 23-28 in Introduction to Logic

Intro to the Language of Predicate Logic

Sample Translations in Predicate Logic

A Second Proof in Predicate Logic


Applying the Quantifier Rules

Elementary Predicate Proof

Let's Do a Proof in Predicate Logic