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Relevance. Premises are relevant to the conclusion when the truth of the premises provide some evidence that the conclusion is true Premises are irrelevant when they do not. Non Sequitur. Latin for “it does not follow” Irrelevant premises. Exercise 2.6A. 1-10 Do as class.
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Relevance • Premises are relevant to the conclusion when the truth of the premises provide some evidence that the conclusion is true • Premises are irrelevant when they do not
Non Sequitur • Latin for “it does not follow” • Irrelevant premises
Exercise 2.6A 1-10 Do as class
Independent Premise • A premise that is intended to provide support for the conclusion by itself
Dependent Premises • A premise that is intended to provide support for the argument’s conclusion only when combined with another premise in the argument
Exercise 2.7 • Break up into groups • A 1-10
2.7A #1 (1) Socrates was a human being (2) All human beings are mortal Therefore, (3) Socrates was mortal Argument with relevant, dependent premises
2.7A #2 (1) Transfatty acids lead to heart disease (2) Children shouldn’t be given foods that lead to heart disease Therefore, (3) Children should not be given foods with transfatty acids Argument with relevant, dependent premises
2.7A #3 • Julia Roberts is either a man or a woman (2) Julia Roberts is a man Therefore, (3) Julia Roberts isn’t a woman Argument with relevant, dependent premises
2.7A #4 • If you walk on the lines in the sidewalk, you’ll be eaten by bears (2) Sometime in the next week, someone will walk on the lines in the sidewalk Therefore, (3) Sometime in the next week, someone will be eaten by bears. Argument. Relevant (but not much) dependent premises
2.7A #5 (I) All cows are pigs (2) All pigs are ducks Therefore, (3) All cows are ducks Argument with relevant, dependent premises
2.7A #6 (1) If Reza had fallen, he would have a bump on his head (2) Reza didn’t have a bump on his head Therefore, (3) Reza didn’t fall Argument with relevant, dependent premises
2.7A #7 (I) The coffee cup was still warm (2) The newspaper was open on the dining room table (3) The microwave was heating up a frozen dinner [4] Each of these three scenes indicate someone was recently present in the room Therefore, [5] If someone was recently in the room, he or she couldn’t have gone far Therefore, (6) The killer couldn’t have gone far Argument with relevant, independent premises
2.7A #8 (1) Many people think that air pollution is a serious problem (2) Vehicle emissions are a significant cause of air pollution Therefore, (3) Most people support laws requiring a reduction in the emissions produced by cars Argument with relevant, dependent premises
2.7A #9 Not an argument
2.7A #10 (I) A survey indicated 26% of voters in favor of Smith (2) A slightly later survey indicated 23% of voters favored Smith Therefore, (3) It is likely that about 25% of voters will favor Smith in the election Argument with relevant, dependent premises
Counter Argument • An argument that draws a conclusion opposed to another argument
Refutation Argument • An argument whose conclusion is that another argument fails the true premises or proper form test
Fallacies • Untrue, false, inaccurate, wrong reasoning • Something you don’t want to commit
Red Herring • The Red Herring fallacy occurs whenever someone makes a statement or offers an argument that distracts attention away from the argument under discussion.
Straw Man FallacyEasy Target Fallacy • When you restate your opponent's argument in an inaccurate way so that you can argue against it
Appeal to Fear • An Appeal to Fear occurs when someone claims that if you don’t do or don’t believe something, something bad will happen to you
Appeal to Pity • Appeals to Pity are a close relative of Appeals to Fear. • An Appeal to Pity occurs when someone claims that if you don’t do or don’t believe something, something bad will happen to someone else.
Appeal to Popularity • The fallacy of Appeal to Popularity occurs when someone argues that a view is true on the grounds that it’s popular
Appeal to Novelty or Tradition • The fallacy of Appeal to Novelty or Tradition occurs when someone argues that a statement is true because people have either believed it for a short time (novelty) or for a long time (tradition).
2.9 • Do as class
Ad Hominem • A person commits the Ad Hominem fallacy when he attacks a person instead of arguing against the view the person asserts
Appeal to Ignorance • Someone commits the fallacy of Appeal to Ignorance when he claims that a statement is true because it hasn’t been shown to be false.
Guilt by Association • A form of the Ad Hominem Fallacy • When people are attacked based upon their association with a person, group or view that is considered objectionable
Begging the Question • When you assume to be truth that which you are trying to prove
Exercise 2.10 • Break up into groups • A 1-10
Two Characteristics of Good Arguments • 1. The premises are true • 2. The argument has proper form
True Premises • The premises are true when what they say about the world is accurate
Proper Form There is a relationship or connection between the premises and conclusion that make you believe the conclusion is true
Deductive Argument You go from a general principle to a specific example It gives necessity
All men are mortal • Socrates is a man Therefore (3) Socrates is mortal
If all the members of the class of things called MEN have a particular characteristic called MORTALITY And Socrates is a member of that class called MEN Then Socrates MUST have that characteristic called MORTALITY
Why? Because we have established a necessary / logical connection between the premises and the conclusion Such that if the premises are true then the conclusion must be true
Examples • All men are mortal (1) All A has B • Socrates is a man (2) C is A There: Therefore (3) Socrates is mortal (3) C has B
Valid Deductive Argument • The conclusion follows necessarily from the premises
Sound Deductive Argument • Valid argument with true premises
Audience • The audience of the argument is the group that the person making the argument wants to convince
The Problem of Ignorance • The problem of ignorance is that we don’t know everything
Modus Ponens (MP) Affirm the Antecedent (1) If A, then B (2)We have A Therefore (3) We can affirm B
Correct Form ExampleAffirm the Antecedent (1) If Mary is a mother (A), then she must be a woman (B) (2) Mary is a mother (A) (3) Therefore, she must be a woman (B)
Incorrect Form Example:Affirm the Consequent (1) If Mary is a mother (A), then she must be a woman (B) (2) Mary is a woman (B) (3) Therefore, she must be a mother (A)