WHAT IS PHILOSOPHY? ARGUMENTATIO N. Intro to Philosophy, Summer 2011 Benjamin Visscher Hole IV

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1 WHAT IS PHILOSOPHY? ARGUMENTATIO N Intro to Philosophy, Summer 2011 Benjamin Visscher Hole IV

2 PHILOSOPHY CONSISTS IN CRITICAL ENGAGEMENT The philosophers we re reading have developed arguments to try to convince you that some proposition is true. Your job is to fight back!

3 SO HOW SHOULD YOU READ? Your goal is to: (A) understand the argument(s), and then (B) critically evaluate the argument(s).

4 SO HOW SHOULD YOU READ? Jim Pryor s three-pass method: 1. Find its Conclusion(s) and Get a Sense of its Argumentative Structure 2. Go Back and Read It Carefully 3. Evaluate the Author's Arguments

5 What is an argument? An argument is a pattern of reasoning in which premises are offered as reasons to believe in the truth of a conclusion. conclusions.

6 What is an argument? An argument is a pattern of reasoning in which premises are offered as reasons to believe in the truth of a conclusion. f conclusions. 1. Premises: reasons (propositions) offered to support the conclusion.

7 What is an argument? An argument is a pattern of reasoning in which premises are offered as reasons to believe in the truth of a conclusion f conclusions. 1. Premises: reasons (propositions) offered to support the conclusion. 2. Conclusion: what the premises are supposed to provide reason to believe.

8 Examples 1. The steps are wet and the sky is grey. 3. All the other times I ve seen that, it s been raining. 2. Therefore, it s probably raining.

9 Examples 1. The steps are wet and the sky is grey. 3. All the other times I ve seen that, it s been raining. 2. Therefore, it s probably raining. 1. All bachelors are unmarried men. 2. John is a bachelor. 3. Therefore, John is an unmarried man.

10 1. Deductive argument. The premises intend to guarantee the conclusion. 2. Inductive argument. The truth of the premises gives us probabilistic reason to believe in the truth of the conclusions. TWO KINDS OF ARGUMENT

11 Two Kinds of Argument: Deductive argument. The premises intend to guarantee the conclusion. Example: 1. Socrates is a man 2. All men are mortal 3. Therefore, Socrates is mortal This is a good deductive argument; if you grant premises, you can t avoid the conclusion.

12 Two Kinds of Argument: Inductive argument. The truth of the premises gives us probabilistic reason to believe in the truth of the conclusions. Example: 1. Every January I ve seen in Seattle has been rainy. 2. This January in Seattle will probably be rainy. This is a good inductive argument. It s evidence for the conclusion, but not a proof of that the conclusion.

13 Deductive arguments What makes a deductive argument a good one? FORM & CONTEN

14 Deductive arguments What makes a deductive argument a good one? Form. Is it impossible for the premises to be true while the conclusion is false? If so, this is a valid argument. An argument is valid if and only if the truth of the premises guarantees the truth of the conclusion. FORM & CONTEN

15 Deductive arguments What makes a deductive argument a good one? Is it impossible for the premises to be true while the conclusion is false? If so, this is a valid argument. Example: 1. If Socrates is a Martian, then Socrates has green skin. 2. Socrates is a Martian. 3. Therefore, Socrates has green skin. What s wrong with this argument? It s valid, but the premises aren t true. FORM & CONTEN

16 Deductive arguments What makes a deductive argument a good one? Content. The second requirement is that the argument be valid and the premises true. That makes the argument sound. An argument is sound if and only if it is valid and has all true premises. FORM & CONTEN

17 Deductive arguments What makes a deductive argument a good one? So the second requirement is that the argument be valid and the premises true. That makes the argument sound. Example (once again): 1. If Socrates is a man, then Socrates is mortal 2. Socrates is a man 3. Therefore, Socrates is mortal FORM & CONTEN

18 What do we do when we argue? We ask people to grant our premises, and then try to demonstrate that they are thereby committed to our conclusions. If we make sound arguments, they ll have no choice. FORM & CONTEN

19 When you read philosophy: (1)Evaluate the argument s form. Reconstruct the argument. Are the premises and conclusion connected in the right way? (2)Evaluate the argument s content. Are the premises true? FORM & CONTEN

20 1. Modus Ponens 2. Modus Tollens 3. Disjunctive Syllogism IMPORTANT FORMS OF ARGUMENT

21 Important forms of argument If Socrates is a man, then Socrates is mortal Socrates is a man Therefore, Socrates is mortal We can formalize this, to show the structure: A => B A Therefore B This is called modus ponens. MoPo

22 Important forms of argument If Socrates is a Martian, then Socrates has green skin. Socrates does not have green skin. Therefore, Socrates is not a Martian We can formalize this, to show the structure: A => B Not B Therefore not A This is called modus tollens. MoTo

23 Important forms of argument Either Socrates is dead, or he has mystic powers of survival. Socrates does not have mystic powers of survival. Therefore, Socrates is dead. A or B Not B Therefore A This is called the disjunctive syllogism. DS

24 1. Affirming the consequent 2. Denying the antecedent 3. False dilemma 4. Post hoc ergo propter hoc 5. Equivocation 6. Argument ad hominem 7. Begging the question 8. Complex question FALLACIES

25 These are the first two fallacies we re looking at: 1. Affirming the consequent 2. Denying the antecedent

26 Affirming the Consequent If Socrates is a man, then Socrates is mortal Socrates is mortal Therefore, Socrates is a man A => B B Therefore A This is called affirming the consequent. AtC

27 I ve just read about a disease that has absolutely no symptoms, and kills you within the day. I feel fine, so I m going to be dead by this evening. AtC

28 Denying the Antecedent If Socrates is an American citizen, then Socrates is a human. Socrates is not an American citizen. Therefore, Socrates is not a human A => B Not A Therefore not B This is called denying the antecedent. DtA

29 People who eat broken glass get sick and die. I don t eat broken glass, so I guess I m immortal. DtA

30 What s wrong with this? I don t know why you won t watch Transformers 3 with me. I never knew you hated watching movies!

31 What s wrong with this: I don t know why you won t watch Transformers 3 with me. I never knew you hated watching movies! This is an example of a false dilemma. 1.Either you want to watch Transformers 3. or you hate watching movies. 2. You don t want to watch Transformers Therefore, you hate watching movies. False Dilemma

32 Another false dilemma exposed False Dilemma

33 What s wrong with this exchange? Homer: Not a bear in sight. The Bear Patrol must be working like a charm. Lisa: That's specious reasoning, Dad. Homer: Thank you, dear. Lisa: By your logic I could claim that this rock keeps tigers away. Homer: Oh, how does it work? Lisa: It doesn't work. Homer: Uh-huh. Lisa: It's just a stupid rock. Homer: Uh-huh. Lisa: But I don't see any tigers around, do you? [Homer thinks of this, then pulls out some money] Homer: Lisa, I want to buy your rock. [Lisa refuses at first, then takes the exchange]

34 This is the fallacy of post hoc, ergo propter hoc. (Latin for: after this, therefore because of this.) It asserts a causal relationship between things which just happen to come after one another.

35 This is the fallacy of post hoc, ergo propter hoc: It asserts a causal relationship between things which just happen to come after one another. Another example: The Cargo Cults built replica airplanes and landing strips to attract airplanes and their cargo.

36 What s wrong with this? The Archchancellor is going to send the Dean to the counterweight continent, where foreigners are killed on sight. Dean: You re sending me to the counterweight continent? But they hate foreigners! Archchancellor: So do you. You should get along famously. - Terry Pratchett, Interesting Times

37 This is an example of equivocation. It uses words to mean different things at different parts of the argument, with the result that an incorrect conclusion is inferred. To make it explicit here: 1. The Dean hates foreigners. 2. The inhabitants of the counterweight continent hate foreigners. 3. Therefore, the Dean and the inhabitants of the counterweight continent will hate the same people.

38 This is an example of equivocation. It uses words to mean different things at different parts of the argument, with the result that an incorrect conclusion is inferred. Further example: 1. A feather is light. 2. What is light cannot be dark. 3. Therefore, a feather cannot be dark.

39 What s wrong with this? Johnny Depp says that quantum mechanics might be successfully combined with relativity via string theory. He s pretty ugly, though, so I don t think he s right.

40 This is the fallacy of arguing ad hominem: against the person, rather than the argument.

41 What s wrong with this? Of course the Bible is God s word. The Bible says so, and God wouldn t lie.

42 What s wrong with this: Of course the Bible is God s word. The Bible says so, and God wouldn t lie. This is the fallacy known as begging the question. It means to assume as a premise what is being argued for in the conclusion.

43 * Note that begging the question isn t the same as asking for a question, in philosophical terms - despite the use of the phrase in ordinary language. Begging the question means that you ve used what you re trying to argue for as a premise in your argument. Further Example: Why should we give criminals the right to a fair trial? When they committed crimes, they showed us that they don t care about our rights!

44 What s wrong with this? Doctor, have you stopped abusing drugs yet?

45 What s wrong with this? Have you stopped abusing drugs? This is the fallacy known as a complex question. It is a fallacy because either way you answer, you admit to having used drugs - even if you haven t!

46 Either you have used drugs before but now don t; or you have used drugs before and still use them now. Therefore, you have used drugs. The question is phrased in a way that hides the fact that the options aren t exclusive.

47 Get to know these fallacies: 1. Affirming the consequent 2. Denying the antecedent 3. False dilemma 4. Post hoc ergo propter hoc 5. Equivocation 6. Argument ad hominem 7. Begging the question 8. Complex question

48 Conclusion: 1. Remember these fallacies. 2. Remember what they all have in common: they involve arguments where the premises don t connect up with the conclusions in the right way. 3. Avoid these fallacies when making your own arguments. 4. Try to spot these fallacies when evaluating arguments.

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