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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
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Non Sequitur
• Latin for “it does not follow”
• Irrelevant premises
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Exercise 2.6A
1-10 Do as class
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Independent Premise
• A premise that is intended to provide support for the conclusion by itself
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Dependent Premises
• A premise that is intended to provide support for the argument’s conclusion only when combined with another premise in the argument
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Exercise 2.7
• Break up into groups • A 1-10
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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
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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
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2.7A #3
(I) 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
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2.7A #4 (I) 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 11
2.7A #5
(I) All cows are pigs (2) All pigs are ducks Therefore, (3) All cows are ducks
Argument with relevant, dependent premises
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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
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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
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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 15
2.7A #9
Not an argument
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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
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Arguing about Arguments
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Counter Argument
• An argument that draws a conclusion opposed to another argument
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Refutation Argument
• An argument whose conclusion is that another argument fails the true premises or proper form test
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Fallacies
• Untrue, false, inaccurate, wrong reasoning
• Something you don’t want to commit
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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.
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Straw Man Fallacy Easy Target Fallacy
• When you restate your opponent's argument in an inaccurate way so that you can argue against it
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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
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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.
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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
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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).
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2.9
• Do as class
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Ad Hominem
• A person commits the Ad Hominem fallacy when he attacks a person instead of arguing against the view the person asserts
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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.
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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
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Begging the Question
• When you assume to be truth that which you are trying to prove
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Exercise 2.10
• Break up into groups
• A 1-10
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Chapter 2 Review
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What makes a Good Argument?
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Two Characteristics of Good Arguments
• 1. The premises are true
• 2. The argument has proper form
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True Premises
• The premises are true when what they say about the world is accurate
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Proper Form
There is a relationship or connection between the premises and conclusion that make you believe the conclusion is true
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Deductive Argument
You go from a general principle to a specific example
It gives necessity
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(1) All men are mortal (2) Socrates is a man Therefore (3) Socrates is mortal
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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
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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
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Examples
(1) All men are mortal (1) All A has B (2) Socrates is a man (2) C is A There: Therefore (3) Socrates is mortal (3) C has B
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Valid Deductive Argument
• The conclusion follows necessarily from the premises
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Sound Deductive Argument
• Valid argument with true premises
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Audience
• The audience of the argument is the group that the person making the argument wants to convince
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The Problem of Ignorance
• The problem of ignorance is that we don’t know everything
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Modus Ponens (MP)
Affirm the Antecedent (1) If A, then B (2)We have A Therefore (3) We can affirm B
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Correct Form Example Affirm 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)
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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)
You must learn the FORM
• 1. If it rains tomorrow (A), then I will bring my umbrella (B)
• 2. I brought my umbrella (B) • 3. Therefore what?
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Correct Form
• 1. If it rains tomorrow (A), then I will bring my umbrella (B)
• 2. It rained (A) • 3. Therefore?
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Modus Tollens (MT)
Deny the Consequent If A, then B We do not have B Therefore, we do not have A
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Correct Form Example Deny the Consequent
(1) If Mary is a mother (A), then she must be a woman (B)
(2) Mary is not a woman (-B)
(3) Therefore, she must not be a mother (-A)
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Disjunctive Syllogism (DS)
Deny the Disjunct Either A or B Either A or B Not A Not B Therefore B Therefore A
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Reductio ad Absurdem (RAA)
Reduce to an absurdity Reduce to a contradiction
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Inductive Arguments
From Specific Examples to General Principle
Gives Probability
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Example
(1) There are trees on Island 1 (2) There are trees on Island 2 (3) There are trees on Island 3 ________________________ (4) All Islands have trees
Weak vs. Strong Inductive Arguments
The more examples / evidence, the stronger
the argument 1,000,000,000 Islands have trees Therefore all Island have trees
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Strong and Weak Inductive Arguments
• Strong Inductive Arguments have many examples (Cogent)
• Weak Inductive Arguments have few examples
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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
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Non Sequitur
• Latin for “it does not follow”
• Irrelevant premises
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Independent Premise
• A premise that is intended to provide support for the conclusion by itself
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Dependent Premises
• A premise that is intended to provide support for the argument’s conclusion only when combined with another premise in the argument
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Counter Argument
• An argument that draws a conclusion opposed to another argument
• What your opponent gives
• An argument against your
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Refutation Argument
• An argument whose conclusion is that another argument fails the true premises or proper form test
• Not necessarily against your argument, but that your argument is wrong
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Fallacies
• Untrue, false, inaccurate, wrong reasoning
• Something you don’t want to commit
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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.
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Straw Man Fallacy Easy Target Fallacy
• When you restate your opponent's argument in an inaccurate way so that you can argue against it
70
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
71
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.
72
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
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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).
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Ad Hominem
• A person commits the Ad Hominem fallacy when he attacks a person instead of arguing against the view the person asserts
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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.
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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
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Begging the Question
• When you assume to be truth that which you are trying to prove
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