“Logic is the study of reasoning — the nature of good (correct) reasoning and of bad (incorrect) reasoning. Its focus is the method by which an argument unfolds, not whether any arbitrary statement is true or accurate. Thus, an argument can be both deductively valid and perfectly absurd, as in 1. All telephone poles are elephants. 2. Sally is a telephone pole. 3. Therefore, Sally is an elephant. The conclusion is valid because it conforms to a correct syllogistic pattern — in this case, affirmation of the antecedent — but is ludicrous at the same time.
As a “branch” of philosophy, logic is often broken down into many subsets: for instance, modal logic, many-valued logic, modern logic, symbolic logic, formal and informal logic, deductive and inductive logic. Those interested in pursuing the subject in depth should read and carefully examine the long articles in The Encyclopedia of Philosophy, especially “A Glossary of Logical Terms.” Each article is followed by an extensive bibliography. (See also Logic.)
A fallacy is an invalid form of argument, an instance of incorrect reasoning. Below is a list of common fallacies. Hit the “Back” button to return to the top.”