[Lecture One] Introduction to Logic
by Dr. Leonard Peikoff
Total Time: 2 hours, 23 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 provides an overview of man’s need for logic and the fundamental rules that guide it. Dr. Peikoff provides a definition of logic, discusses its origins in the thought of Aristotle, and reviews the basic axioms of logic.
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 facts give rise to man’s need of logic? |
| Why do all men need logic? |
| Why is logic both an intellectual and an existential need of man? |
| How does logic play a role in politics? |
| What are the differences between ontological and non-ontological approaches to logic? |
| What is the fundamental basis of the laws of logic? |
| How does Dr. Peikoff define logic? |
| How are the three Aristotelian laws of logic all contained in one? |
| What is the definition of proof? |
| How does the doctrine of mysticism undermine logic? |
| How does the doctrine of subjectivism undermine logic? |
| In what ways do mysticism and subjectivism differ in view of how they attack logic? |
| Why do both mysticism and subjectivism cut the mind off from reality? |
| Explain the error behind demanding a proof for the law of identity. |
| Work out an example of how Aristotle would handle a skeptic about logic. |
Q&A Guide
Below is a list of questions from the audience taken from this lecture, along with (approximate) time stamps.
| 1:45:30 | Could you suggest reading material aside from Aristotle? |
| 1:47:57 | Many universities do not have a traditional course as you describe it. They begin by describing logic as the study of how to manipulate sentences to preserve truth value. Such courses are anti-conceptual and require only mechanical symbol manipulations as proof. What should we do if required to take such a course? |
| 1:52:02 | Why is comparatively little known about inductive reasoning and what kinds of observations will be required to achieve such knowledge? |
| 1:52:59 | Is there any serious attempt or possibility to defend mysticism without subjectivism or the other way around, i.e., is the connection always one of psycho-epistemology? |
| 1:55:15 | Recalling that Marx was a materialist, which he claimed was based on sense perception, and that he claimed dialectic materialism was derived from observation of reality, in what sense would you claim that Marx represents a non-ontological approach to logic? |
| 1:57:16 | Is there any important reason as to why logic is defined in terms of identification and in terms of thinking? |
| 1:58:29 | You said that logic is the art of non-contradictory identification. Why did you use the word “art”? |
| 1:59:51 | Please comment on the relationship between a volitional consciousness and one that is fallible. Does one presuppose the other? |
| 2:01:32 | Does the law of the excluded middle, which allows only the extremes, relate to or contradict Aristotle’s ethics of the Golden Mean? |
| 2:03:12 | Why are so many colleges today offering courses in mysticism, such as astrology? |
| 2:05:47 | Wasn’t the Roman Catholic religion based on logic many, many years ago? |
| 2:08:19 | Could you define “induction” and “deduction”? |
| 2:08:32 | Would you repeat the definition of “proof” that you gave (the last one)? |
| 2:09:37 | What was the source of the quote by the follower of Bergson? |
| 2:10:08 | Why is the implementation of logic considered an art rather than a skill |
| 2:10:52 | How does the law of excluded middle apply to borderline cases, that is existents that are neither clearly A- nor non-A? |
| 2:13:08 | Would you please review Aristotle’s argument against conclusions viewed as opinions? You made some analogy about health being more important to a non-healthy man? |
| 2:15:28 | In place of inference, I am more familiar with the term “judgment.” If one exists, may I have a distinction through definitions? |
| 2:16:42 | What is the relation between the terms “reason” and “logic”? |
| 2:18:15 | What is the definition for the term “proposition”? |
| 2:19:14 | Is our society so irrational that we cannot rid our young of the many socialists that teach in our American universities today? |