1. Informal Logic and Thinking Tools!

2. Definition…Logic What is an argument?
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.

3. 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

4. The 6 Mistakes We Make in Thinking (Kida, 2007)

5. The 6 Mistakes We Make in Thinking (Kida, 2007)
1. We prefer stories to statistics. OR
Which do YOU prefer?

6. 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?

7. 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?

8. 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?

9. 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.

10. 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!

11. Some notes to consider…
First, arguments can be either really short or they can be really long (like op-eds and books,)
long arguments should be made in a series of shorter ones.
Second, its important to recognize that having an argument doesn’t mean that your argument is any good. premises may be false irrelevant to the conclusion, or that they fail entirely to support the conclusion.

12. 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). It helps tell why.

13. Not everything is an argument
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)

14. 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.

15. 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.

16. 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

17. Syllogisms –
A=B Some C=B Some A=C NOPE!!!

18. Types of Arguments! Deductive argument Inductive argument
Argument whose premises make its conclusion certain.
Argument who premises make its conclusion likely.

19. Aristotle Considered the Father of Logic
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

20. 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?

21. All men are mortal Mo
Mortal
men
mortals

22. Socrates is a man
men

23. Socrates is mortal
men
mortals

24. And another thing….
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
Conclusion: The mayor probably won’t be reelected.

25. 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

26. Bell Ringer Review… What is a premise? What is a conclusion
What is a Syllogism?

27. 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.”

28. More Enthymeme
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. )

29. Example 1
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.

30. Example 2
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.)

31. Another example… Peach number 1 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.

32. Validity
A deductive argument is valid if 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.

33. Checking Validity
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

34. Practice #1-the counter argument
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

35. Practice…#1The Counter argument 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…

36. Example…Alice’s premise
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

37. The Counter argument… The Hatter responds…
“I see what I eat (A)” is the same thing as “I eat what I see! (B)”
A is B

38. Practice #1-the counter argument
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…

39. Answer…
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!”

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

41. Practice #2…Venn Diagram..
Rules for shading:
1. add argument form to the syllogism and label the circles
2. Within your syllogism, identify the qualifiers (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.
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.

42. Example 1 P: all Labradors are dogs Argument form: All L are D
Quantifier: All

43. Example 2 P= No cats are dogs Argument form: No C are D Quantifier: No
(remember No= nothing in common)

44. All orchids are Cattyleas.

45. All ribosomes are structures in the cytoplasm.

46. Some musicians are not pianists.

47. Some sculptors are not painters.

48. Let’s try two premises
All pollution-free devices are completely efficient machines.
No automobiles are completely efficient machines.
No automobiles are pollution-free devices.

49. And again No logic teachers are benevolent persons.
Some dictators are benevolent persons.
Some dictators are not logic teachers.

50. 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.)

51. Examples…
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.

52. And another…
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!

53. Welcome Back! Monty Python and the Argument Clinic
Agenda and Objectives: By analyzing video clips students will identify common fallacies.

54. Burn the Witch!!!
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

55. Breakdown of the argument…
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)

56. Anything valid??
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

57. Do the same for the following clips. 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.

58. Lexus Moments
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.

59. Twilight zone
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).

60. No regrets…
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.

61. Trump-Hitler
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.