[Lecture Six] Introduction to Logic
by Dr. Leonard Peikoff
Total Time: 2 hours, 35 minutes
Course summary: This lecture course by Dr. Leonard Peikoff provides a comprehensive introduction and overview of the study of logic. Through exercises provided to the reader and discussion of answers, the course covers definitions, syllogisms, fallacies, and the rules of generalization. It is equivalent to a university level course in logic. Read more »
In this lecture: This lecture continues the analysis of syllogistic reasoning. Dr. Peikoff works through immediate inferences, contradictions, contraries, alternatives, and implications.
Study Guide
This material is designed to help you digest the lecture content. You can also download below a PDF study guide for the entire course.
| What is the value of understanding the immediate inference? |
| What does it mean for statements to be contradictory? |
| What does it mean for two statements to be contrary? |
| What does it mean for two statements to be sub-contrary? |
| What does it mean for two statements to be sub-alternative? |
| What are the sub-implicant and super-implicant of a statement? |
Q&A Guide
Below is a list of questions from the audience taken from this lecture, along with (approximate) time stamps.
| 56:44 | Would you please review why the predicate term is distributed in “some S is not P”? |
| 2:14:14 | Do you have any comment on Ambrose Bierce’s quote condemning logic? |
| 2:17:57 | Can syllogisms be expressed via diagram? |
| 2:18:59 | You stated that you were philosophically opposed to reducing hypothetical categoricals. Would you explain why? |
| 2:21:41 | What, if any, is the difference between a group and a class? |
| 2:22:51 | Does my argument for free will beg the question? “If man did not have free will, he could not have knowledge. Man has knowledge, therefore he has free will.” |
| 2:26:26 | Do you say that a dog or cat has knowledge? |
| 2:27:32 | Would you care to comment on how ignorantiam is used by the government to regulate business? |
| 2:29:49 | Is misuse of the mean a subcategory of cliché thinking? |
| 2:30:29 | Certain of the rules that you gave us about inferring one proposition from another do not apply if you’re talking about a null class… |
| 2:32:54 | What is the relationship between the axiom of existence and the axiom of identity? |