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Introduction to Logic

Leonard Peikoff

Date: n/a

This course (with exercises) covers the standard topics taught in introductory courses in Aristotelian logic. It defines the principles of valid reasoning, and discusses prevalent logical fallacies. It formalizes the steps by which one derives conclusions from premises, and it provides a methodology by which to evaluate one's own thinking processes. (Each lecture includes a question period.)

1. Basic Logical Theory
The cognitive role of logic. The laws of logic and their validation. Logic vs. mysticism and subjectivism. Logic and reality.

2-3. Informal Fallacies
Twenty-two common fallacies, including: the appeal to authority, ad hominem, ad populum, ad ignorantiam, begging the question, equivocation, composition, division, misuse of the mean and false alternative.

4. Introduction to Deductive Reasoning
The nature of deductive argument. Validity and truth. Mixed and pure hypothetical arguments. Alternative arguments.

5.-6. The Aristotelian Syllogism
Categorical propositions. Immediate inference. Rules of syllogistic validity. Analyzing arguments in ordinary language.

7-8. Definition
The cognitive role of definitions. Genus and differentia. The method of formulating valid definitions: five Aristotelian rules of definition. Definitional fallacies.

9-10. Inductive Generalization
Induction vs. deduction. Induction by simple enumeration. Experimental induction: Mill's methods of discovering causal connections. Major inductive fallacies, including: hasty generalization, oversimplified generalization, post hoc. The justification of induction. The argument from analogy.

Recorded in 1974.

logic

Parts: 10

Handout: none

Publications: