This preview shows page 1. Sign up to view the full content.
Unformatted text preview: Philosophy 201 Philosophy Introduction to Logic
Prof. A. T. Anchustegui Logic Logic Logic is the study of the principles of correct reasoning. What makes a good argument? What makes a bad argument? What principles can we use to distinguish between good and bad arguments? Argument Argument A vehicle of persuasion in which least one statement is offered in support of another statement. The ‘premise’ is the evidence or support. The ‘conclusion’ is the statement supported. Statements Statements Statements are linguistic items that are either true or false. A statement is a sentence in declarative form that makes an assertion. Some linguistic items that are not statements are questions and commands. What time is it? Shut the door! Argument or not? Argument
Which of the following are arguments? 1. Forbear to judge, for we are sinners all. 2. Close your mouth. 3. Close your mouth, for you have very bad breath. 4. Open the door! For you are letting in too much cold air! Continued… Continued…
4. Since you stayed out late all night, you are grounded for a week! 5. He bought me flowers and sent me a card. Therefore, he loves me. 6. A bat uses echolocation to move through the environment. 7. Eat your dinner! Review Review What is logic? What is a statement? What distinguishes premises from conclusions? What are some other nonargumentative uses of language? Informal Fallacies Informal A fallacy is an error in reasoning. We will look at three types of informal fallacies: fallacies of relevance, fallacies of presumption, and fallacies of ambiguity. Fallacies of Relevance Fallacies When the conclusion of an argument relies on premises that are irrelevant to it, the argument commits a relevance fallacy. Often the premises appear relevant at first, but on closer inspection, the premises really have nothing to do with the truth of the conclusion. Fallacies of Relevance Fallacies
1. 2. 3. 4. 5. 6. 7. Argument from Ignorance Appeal to inappropriate authority Ad Hominem: Abusive and Circumstantial Appeal to Emotion Appeal to Pity Appeal to Force Irrelevant Conclusion Fallacies of Presumption Fallacies
1. 2. 3. 4. 5. Complex Question False Cause Begging the Question Accident Converse Accident Fallacies of Ambiguity Fallacies
1. 2. 3. 4. 5. Equivocation Amphiboly Accent Composition Division Categorical Propositions Categorical Deductive Validity
A deductively valid argument is one in which it is impossible to have all true premises and a false conclusion. A deductively valid argument is one in which all the information in the conclusion is contained in the premises. Categorical Propositions Categorical
Universal Affirmative All As are Bs Universal Negative No As are Bs No universal statement implies existence Continued… Continued…
Particular Affirmative Some As are Bs Particular Negative Some As are not Bs All particular statements do imply existence. “Some” means “at least one exists” Venn Diagrams Venn Universal Affirmative
animals cats All animals are cats Universal Negative Universal No animals are cats animals cats ...
View Full Document
This note was uploaded on 02/03/2011 for the course PHIL 201 taught by Professor Peterhodges during the Spring '08 term at Boise State.
- Spring '08