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Informal Logic and Thinking Tools!. What’s going on here???. Burn the Witch!!!!. Definition…Logic. The study of the nature of arguments. Know known as “Critical Thinking.” Developed by the Greek Philosopher Aristotle. What is an argument?

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What s going on here
What’s going on here???

Burn the Witch!!!!


Definition logic
Definition…Logic

  • The study of the nature of arguments.

  • Know known as “Critical Thinking.”

  • Developed by the Greek Philosopher Aristotle.

  • What is an argument?

  • a group of statements that attempt to establish a claim.

  • Conclusion—the claim that an argument is trying to establish.


Why study logic
Why study Logic?

• Logic is the foundation of “deep thinking” or

Philosophy

• Learning to think logically will help you

become a better philosopher

• Becoming a better philosopher will make

philosophy more enjoyable

• You will stop believing whatever you hear and

start asking “why?” or “by what argument?”

• You will be able to better formulate your own

Arguments

• You will be able to spot fallacies


Welcome back
Welcome Back!

  • Bell Ringer…

  • Objective and Agenda: Through notes, discussion, and scenarios, students will identify the components of an argument.

  • QUIZ TOMORROW!

  • What is Logic?

  • What is an argument?



The 6 mistakes we make in thinking kida 20071
The 6 Mistakes We Make in Thinking (Kida, 2007)

1. We prefer stories to statistics.

OR

Which do YOU prefer?


The 6 mistakes we make in thinking kida 20072
The 6 Mistakes We Make in Thinking (Kida, 2007)

2. We seek to confirm, not question, our ideas.

We see what we want to see

But is this professional?


The 6 mistakes we make in thinking kida 20073
The 6 Mistakes We Make in Thinking (Kida, 2007)

3. We rarely appreciate the role of chance and coincidence.

Yes.

Could this be a coincidence?


The 6 mistakes we make in thinking kida 20074
The 6 Mistakes We Make in Thinking (Kida, 2007)

4. We sometimes misperceive the world around us.

Is this a face on Mars!?

Or a problem with our focus?


The 6 mistakes we make in thinking kida 20075
The 6 Mistakes We Make in Thinking (Kida, 2007)

5. We tend to oversimplify our thinking.

Is Hillary Orwellian?

Is Bush a Dunce?

The truth is probably more complex.


The 6 mistakes we make in thinking kida 20076
The 6 Mistakes We Make in Thinking (Kida, 2007)

6. Our memories are often inaccurate.

Researchers are able to purposely create false memories.

Hypnotists can do it by mistake!


Some notes to consider
Some notes to consider…

  • First, arguments can be either really short or they can be really long (like op-eds and books,) but really long arguments will usually be broken down into series of shorter ones.

  • Second, its important to recognize that having an argument doesn’t mean that your argument is any good. An argument might be such that its premises are false or irrelevant to the conclusion, or that they fail entirely to support the conclusion.


Arguments vs explanations
Arguments vs. Explanations

  • Both answer the questions why? So it can be tricky to tell the difference.

  • Argument- answers the question “Why should I accept this conclusion?”

  • Explanation-takes the conclusion as a given (as a fact) and then offers a story about why that particular thing is the case rather than thatit is the case.


Not everything is an argument!“A string of statements asserting or clarifying…views does not an argument make”

  • Not an argument:“I hate George Bush. Every time I see his face I want to step on it.” (assertion)

  • Not an argument:“I can’t stand Hillary Clinton. She’s such a Woman of the ‘80s--you can imagine her in a power-suit with shoulder-pads out to there and a scarf tied in a bow as a pretend necktie.” (clarification)

  • Not an argument:“I don’t like Obama or Romney either.” (statement in the interest of being Fair and Balanced)


Examples
Examples…

Ms. Krall: You didn’t turn your homework in Sally.

Sally: My dog ate my homework.

  • Sally is offering an explanation for why it is that she failed to turn in her homework.

  • She is not trying to convince me that she failed to turn it in; We both agree that she failed to turn it in.


Examples1
Examples

  • Billy: Why did I fail this class. Ms. Krall?

  • Ms. Krall: You didn’t turn in your work, Billy.

  • Billy: My dog ate my work.


Comparing the two
Comparing the two…

  • Although both sentences are identical, Billy is offering an argument.

  • He is claiming (implying) that he shouldn’t fail because his dog ate his work.

  • And it’s his intentions that makes his sentence an explanation


Logic workbook
Logic Workbook

  • Answer the 5 discussion problems

  • Share with your group.


Good morning
Good Morning!

  • Bell Ringer…

  • Agenda and Objectives: Through notes and an activity students will identify premises and conclusions to deductive arguments.

  • Define Logic

  • Define argument

  • What’s the difference between an argument and explanation?

  • Quiz on Friday!


Welcome back1
Welcome Back!

  • Take a few minutes to review for your quiz…


Good morning1
Good Morning!

  • Agenda and Objectives: Through notes and an activity students will identify premises and conclusions to deductive arguments.


Types of arguments
Types of Arguments!

  • Deductive argument

  • Inductive argument

  • Argument whose premises make its conclusion certain.

  • Argument who premises make its conclusion likely.


Aristotle
Aristotle

  • Considered the Father of Logic

  • Syllogism- “an extremely subtle, sophisticated, or deceptive argument.” (Deductive Reasoning)

  • Orconsists of exactly three claims, two of which are premises and one of which is the conclusion


Breakdown of the argument
Breakdown of the argument…

  • Premise: a reason offered as support for another claim

  • Conclusion: the claim being supported by a premise or premises

  • Argument: a conclusion together with the premises that support it

  • So, to take the oldest example in logic, one that Aristotle used in teaching at his Academy:

  • 1. All men are mortal.

  • 2. Socrates was a man.

  • 3. Therefore Socrates is mortal

  • What is the conclusion?

  • What are the premises?


All men are mortal
All men are mortal

Mo

Mortal

men

mortals


Socrates is a man
Socrates is aman

men


Socrates is mortal
Socratesismortal

men

mortals


And another thing
And another thing….

  • Sometimes premises can have more than one conclusion.

  • Ex. Since yesterday’s editorial cartoon succeeded in making the mayor look silly, the cartoonist must have finally regained his touch. And the mayor probably won’t be reelected.

Premise: Yesterday’s editorial cartoon succeeded in making the mayor look silly.

Conclusion: The cartoonist has finally regained his touch.

And

Premise: Yesterday’s editorial cartoon succeeded in making the mayor look silly.

Conclusion: The mayor probably won’t be reelected.


Identify premises and conclusions
Identify premises and conclusions…

  • Premise Indicators

  • Since

  • Because

  • For

  • As

  • Follows from

  • As shown by

  • Inasmuch as

  • As indicated by

  • The reason is that

  • May be inferred from

  • May be derived from

  • May be deduced from

  • Given that

  • Conclusion Indicators

  • Therefore

  • Hence

  • So

  • Accordingly

  • In consequence

  • Consequently

  • Proves that

  • As a result

  • Thus

  • For this reason

  • For these reasons

  • It follows that

  • I conclude that

  • Which shows that

  • Which means that

  • Which entails that

  • Which implies that

  • We may infer


Review
Review!

  • Syllogism- “an extremely subtle, sophisticated, or deceptive argument.” (Deductive Reasoning)

  • Or consists of exactly three claims, two of which are premises and one of which is the conclusion


Bell ringer review
Bell Ringer Review…

  • What is a premise?

  • What is a conclusion

  • What is a Syllogism?


Activity
Activity…

  • With a neighbor, identify the premise(s) and conclusion (s) of each argument.

  • Underline the premise(s)

  • Circle the conclusion (s)



The enthymeme
The Enthymeme

  • “a syllogism or other argument in which a premise or the conclusion is unexpressed.”

  • Meaning- it’s implied!!!

  • Example: “I live in Wisconsin, so I am probably a Green Bay Packer Fan”

  • What is the missing premise?

  • “Most people from Wisconsin are Green Bay Packer Fans.”


However sometimes premises or conclusions are implied page 13
However, sometimes premises or conclusions are implied (page 13.)

  • Ex. “You spilled it. Whoever makes the mess cleans up the mess.”

  • What is clearly implied here is the conclusion: You clean up the mess.

  • Ex. You should not eat that greasy hamburger. It is loaded with fat.

  • What is the implied premise?

  • (You should not eat anything that is loaded with fat. )


Example 1
Example 1 13.)

  • Bill only owns blue pants and brown pants. Bill is wearing a pair of his pants today. So Bill is wearing either blue or brown pants today.

  • Deductive! The two premises (first 2 sentences) guarantee the truth of the conclusion.


Example 2
Example 2 13.)

  • January has always been cold here in Siberia. Today is January 14, so it is going to be another cold day in Siberia.

  • Inductive.Premise makes the conclusion likely, but does not guarantee that the conclusion is true. (it is possible that the premise could be true and the conclusion could still be false.)


Another example
Another example… 13.)

  • Peach number 1 contains a pit.

  • Peach number 2 contains a pit.

  • Peach 3 contains a pit…and so on until…

  • Peach 1,000 contains a pit.

  • Conclusion: All peaches contain pits!

  • The premises do not logically entail the conclusion-it remains possible that the 1,001st peach will not contain a pit. Still despite not being deductively valid, we still suppose the conclusion will be true.


Good morning3
Good morning… 13.)

  • Bell Ringer…

  • Agenda and Objective: Through exercises students will identify invalid statements by using the counter argument and Venn Diagram strategies.

  • Turn to page 5 in your packet. Read about “Point of Issue” and do the 5 exercises. What is the point of each argument?


Packet exercises
Packet Exercises… 13.)

  • Premise: All human beings (a) are mortal (b)

  • Premise: Corky (c) is a human being (a)

  • Conclusion: Corky (c) is mortal (b)

  • All A are B

  • C is A

  • Therefore C is B


Validity
Validity 13.)

  • A deductive argument is validif it has a form that would make it impossible for the premises to be true and the conclusion false.

  • If a deductive argument is valid, then its premises' being true would guarantee that its conclusion is true.


Checking validity
Checking Validity 13.)

  • Valid- logical form of argument whereas “Truth” refers to the relationship of a statement to the objects that it describes in the world.

  • Some arguments can be valid with false premises.

  • Invalid- has some problems with its logical form, such as an ambiguous key term. It is possible for an invalid argument to have all true premises.

  • Two ways…

  • Counter argument

  • Venn Diagram


Practice 1 the counter argument
Practice #1-the counter argument 13.)

  • The most convincing way to show invalidity of an argument is to present a counter example

  • In defining the case for invalidity, the premises are true but the conclusion is false


Practice 1the counter argument from alice s adventures in wonderland
Practice…#1The Counter argument 13.)From Alice's Adventures in Wonderland

  • “Then you should say what your mean,” the March Hare went on.

  • “I do, “ Alice hastily replied; “at least-at least I mean what I say-that’s the same thing, you know.”

  • “not the same thing a bit!” said the Hatter. “you might just as well say that ‘I see what I eat’ is the same thing as “I eat what I see’!”

  • “you might just as well say,” added the March Hare, “that ‘I like what I get’ is the same thing as ‘I get what I like’!”

  • “you might just as well say,” added the Dormouse, who seemed to be talking in his sleep, “that “I breathe when I sleep’ is the same thing as “I sleep when I breathe’!”

  • It is the same thing with you,” said the Hatter, and here the conversation dropped, and the party sat in silent for a minute…


Example alice s premise
Example…Alice’s premise 13.)

  • Premise: “I say what I mean is the same as I mean what I say.”

  • Argument Form:

  • (A) I say what I mean is the same as (B) I mean what I say

  • A is B


The counter argument
The Counter argument… 13.)

  • The Hatter responds…

  • “I see what I eat (A)” is the same thing as “I eat what I see! (B)”

  • A is B


Practice 1 the counter argument1
Practice #1-the counter argument 13.)

  • From Alice's Adventures in Wonderland do the following…

  • Put the premises on the March Hare and the Dormouse into argument form and explain how they represent the use of counter example to show invalidity…


Answer
Answer… 13.)

  • The March Hare

  • Argument Form..(A) “I like what I get” is the same thing as (B) “I get what I like!”

  • A is B

  • (first statement is true, second false)

  • The Dormouse

  • Argument form: (A) “I breathe when I sleep” is the same thing as “I sleep when I breathe!”

  • A is B

  • (first statement is true, second false)


Checking validity1
Checking validity 13.)

Valid

Invalid

Has some problems with its logical form, such as being ambiguous. It is possible for an invalid argument to have all true premises.

  • Refers to the logical form of an argument whereas “truth” refers to the relationship of a statement to the objects it describes in the world.

  • So an argument can be valid with false premises


Counter example
Counter example… 13.)

  • “used to argue that a certain philosophical position is wrong by showing that it does not apply in certain cases.”

  • 1. the worth of an argument depends on the form(s) that the argument creates.

  • 2. The defining case of invalidity occurs when the premises are true and the conclusion is false. (All dogs are animals, All cats are animals Therefore, all cats are dogs.)

  • 3. It should be possible to show the invalidity of an argument by reducing that argument to one that is obviously bad or invalid by applying counter examples.


Steps
Steps… 13.)

  • No famous celebrities are poor people.

    Some computer geniuses are not poor people.

    So, Some computer geniuses are not famous celebrities.

  • A= famous celebrities.B=poor people.C= computer geniuses.


Next step
Next step 13.)

  • Now think of statements or terms to substitute that produce a well-known falsehood when substituted for the variables in the argument.

  • Let’s use dogs to replace geniuses and animals to replace celebrities…

  • No A are B.Some C are not B.So, Some cats are not animals.

  • No animals are B.Some cats are not B.So, Some cats are not animals.


Further
Further… 13.)

  • Find statements that, if substituted for the associated remaining variables in the argument, produce premises that are well-known truths.

  • No animals are volcanoes.Some cats are not volcanoes.So, Some cats are not animals.


Practice 2 venn diagram
Practice #2…Venn Diagram.. 13.)

  • Diagram both Premises in the picture

  • See if the conclusion is represented in the picture

  • If the Conclusion is not shown in the diagram, the syllogism is invalid: if it is, it is valid.

  • Rules for shading:

    1. add argument form to the syllogism and label the circles

    2. Within your syllogism, identify the qualifies (all, no, some)

    3. Shading show emptiness and means that there are no entities in the shaded area.

    4. Do the universal quantifiers all and no first.


Example 11
Example 1 13.)

  • P: all Labradors are dogs

  • Argument form: All L are D

  • Quantifier: All


Example 21
Example 2 13.)

  • P= No cats are dogs

  • Argument form: No C are D

  • Quantifier: No

  • (remember No= nothing in common)


Welcome back2
Welcome Back… 13.)

  • Bell Ringer…review yesterday’s Venn Diagrams

  • Agenda and Objectives: Through notes, worksheet, and discussion students will identify fallacies in reasoning.


All orchids are cattyleas
All orchids are 13.)Cattyleas.


All ribosomes are structures in the cytoplasm
All 13.)ribosomes are structures in the cytoplasm.




Let s try two premises
Let’s try two premises 13.)

  • All pollution-free devices are completely efficient machines.

  • No automobiles are completely efficient machines.

  • No automobiles are pollution-free devices.


And again
And again 13.)

  • No logic teachers are benevolent persons.

  • Some dictators are benevolent persons.

  • Some dictators are not logic teachers.


Fallacies and booby traps to arguments or simply mistakes in reasoning
Fallacies and Booby Traps to arguments (or simply mistakes in reasoning)

  • Arguments fail due to…

  • One of the premises is false

  • When conclusion does not properly follow the premises.

  • Or booby traps! (argument, while not a fallacy itself might lead an inattentive reader to commit a fallacy.)


Examples2
Examples… in reasoning)

  • Whichever candidate receives the greatest share of the popular vote will be elected President.

  • Al Gore received more votes than George Bush.

  • Therefore, Al Gore was elected President of the United States.

  • Which premise is false and why?

  • Getting the most votes is not the way one gets elected President.

  • Therefore it is unsound.


And another
And another… in reasoning)

  • If Burger King sells Big Macs, then McDonald’s will go out of business.

  • Burger King does sell Big Macs.

  • Therefore, McDonald’s will go out of business.

  • Although formally sound, why is this false?

  • Because BK is not in the business of selling Big Macs!


Welcome back3
Welcome Back! in reasoning)

  • Monty Python and the Argument Clinic

  • Agenda and Objectives: By analyzing video clips students will identify common fallacies.


Burn the witch
Burn the Witch!!! in reasoning)

  • As you watch the video clip consider the following questions.

  • What is the argument being offered?

  • Evaluate the arguments for fallacies and/or booby-traps.

  • Share with neighbor


Welcome back4
Welcome Back! in reasoning)

  • Bell Ringer:

  • Define: Straw Man, General Fallacy, Undistributed Middle

  • Agenda and Objectives: By analyzing video clips students will identify common fallacies.


Breakdown of the argument1
Breakdown of the argument… in reasoning)

  • 1. All witches are things that can burn

  • 2. all things that can burn are made of wood

  • C=.therefore all witches are made of wood (1,2)

  • 4. all things that are made of wood are things that can float

  • 5. all things that weigh as much as a duck are things that can float.

  • 6. C1=so all things that weigh as much as a duck are things that are made out of wood (4, 5)

  • 7. C2=therefore, all witches are things that weigh as much as a duck (3,6)

  • 8. this thing is a thing that weighs as much as a duck

  • C= therefore, this thing is a witch! (7,8)


Anything valid
Anything valid?? in reasoning)

  • The first argument (1,2,3) is valid. This is 3 really does follow logically from 1 and 2.

  • That’s not to say that it’s convincing because premise 2 is rather obviously false. Still, if 2 were true, then the conclusion would have to be true as well.

  • However, arguments 2 (4,5,6), 3 (3,6,7), and 4 (7, 8, 9) are false.

  • Commits the fallacy of the “undistributed middle.”

  • All A is C

  • All B is C

  • Therefore, all A is B


Common fallacies and booby traps
Common Fallacies and Booby Traps in reasoning)

  • Fallacy-“incorrect reasoning in argumentation resulting in a misconception”

  • Booby traps- “causing somebody to infer a false conclusion.”

  • Look over handout discussing different types of Fallacies and booby Traps

  • With a partner, evaluate arguments on the list.

  • Identify fallacy (fallacies) or booby trap(s)


Do the same for the following clips what are the fallacies
Do the same for the following clips. in reasoning)What are the Fallacies?

  • Lexus “Moments”

  • Vernon Robinson “Twilight Zone”

  • Coca Cola “no More Regrets for Old Man”

  • MoveOn.org “Bush-Hitler”

  • Hints: They are either equivocation, straw man, false cause, undistributed middle, genetic fallacy (or some combination!)

  • Share with neighbor.


Lexus moments
Lexus Moments in reasoning)

  • It is one long (very well done) red herring. The general approach is always the same: Invoke a number of positive images and then place your product at the very end.

  • Many ads use sex in this way

  • The Lexus spot provides quick cuts of multiple good images, with corresponding voice-over. At the end viewers are invited to savor all of life’s moments…while being treated to an image of a Lexus driving down the road.


Twilight zone
Twilight zone in reasoning)

  • equivocating on “aliens,” suppressed evidence (that it is not, in fact, illegal to say “under God” in the pledge of allegiance; that Jackson and Sharpton support racial quotas which are, in fact, already illegal), and straw man (“you can burn the American flag and kill babies” pretty seriously oversimplifies the arguments at issue).


No regrets
No regrets… in reasoning)

  • This is a instance of a false cause fallacy. In the commercial, drinking a Coke causes the old man to go out and do all the things that he’s never done before. Obviously, though, there is no evidence that drinking a Coke will actually cause this sort of behavior.


Bush hitler
Bush-Hitler in reasoning)

  • This is a special instance of the genetic fallacy, one common enough that some lists of fallacies include it as a separate instance. The basic structure of the argument is something like the following:

    Person X did/said/believed some particular thing Y.

    Hitler also did/said/believed Y.

    Therefore, we ought to reject Y.

  • OR

    Therefore, person X is just as bad as Hitler.

  • The first of those conclusions is a genetic fallacy. The second possible conclusion is an undistributed middle. The “Bush-Hitler” ad is doing the second of those two things.


Welcome back5
Welcome Back! in reasoning)

  • Bell Ringer… Check with your neighbor and compare answers from Friday’s argument worksheet

  • Agenda and Objective: Through review, students will identify invalid arguments through counter examples and Venn diagrams


Good morning4
Good Morning! in reasoning)

  • Bell Ringer…

  • Agenda and Objective: Through notes and partner activity students will identify arguments through formulation as well as identify validity.

  • What is an Enthymeme?


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