Parts
2-5
Basic Components,
Structure and Logic of
Argumentation
Part
2
Basic Components of
Argumentation
“Master the machinery of [logic], and you have a mental
occupation always at hand… that will be of real use to
you in any ...
Contents of this Presentation
Click below to jump to a section

Part 1: Elements of an Argument
1. Key Terms
2. Identifyin...
Part 1:
Elements of an Argument
1. Argumentation Key Terms
2. Identifying Conclusions
3. Identifying Premises
Argumentation Key Terms
Claim: a statement or opinion that is either true or
false
Argument: a claim supported by premises...
Claim
Claim: an assertion about the truth, existence, or
value of something that is either true or false
❖ Claims are also...
Argument
Argument: an assertion that contains
BOTH a conclusion and premises
○ Not all statements are arguments
○ A statem...
Click to View the Linked YouTube Video Below
Which of the following is an argument?
Vending machines stocked with soda or candy
should be removed from all public schoo...
Conclusions
Conclusion: The main claim of an argument that
is supported by a premise
○ It’s the logical result of the rela...
Click to View the Linked YouTube Video Below
2 Keys to Identifying the Conclusion
1. Ask, “Is the statement the main point, or is it a claim
given to support another s...
Premises
Premise: A reason offered as support, or
evidence, for another claim.
These are often indicated by the words:
○ B...
Premises
Today's freshmen cannot write very well. Joe is a
freshman, so he must be a poor writer.
Premise

Today's freshme...
What is the Conclusion in each
of the Following Arguments?

Abortion is wrong because all human life is sacred.
❖ Abortion...
What is the Conclusion in each
of the Following Arguments?

John will probably receive the next promotion since he’
s been...
What is the Conclusion in each
of the Following Arguments?
It’s a beautiful day. We should go to the park.
Besides, I need...
Claim: statement about the truth or
value of something that is either true or
false

Argument: a conclusion and a
supporti...
CLICK HERE
for Practice Identifying the
Premises and Conclusions of
Arguments
Part 3:
Standard Argument Form

Identify the Premises and Conclusion
Identify the Premises and Conclusion
Rewrite the argument in standard form
● Step 1: Identify which claim is the conclusio...
Identify the Premises and Conclusion
All black dogs are warm-blooded because they are
mammals, and all mammals are warm-bl...
Identify the Premises and Conclusion
All black dogs are warm-blooded because they are
mammals, and all mammals are warm-bl...
Identify the Premises and Conclusion
He must be a good basketball player. After all, he’s
tall, and all tall people are go...
Identify the Premises and Conclusion
He must be a good basketball player. After all, he’s
tall, and all tall people are go...
Identify the Premises and Conclusion
The weather report is calling for blizzard conditions.
Driving could be hazardous. St...
Write it in Standard Form
Start on your homework now. You will get done
earlier and still have time to watch the movie wit...
Identify the Premises and Conclusion
If all employers require their employees to take a flu
shot, then less people would t...
Identify the Premises and Conclusion
If all employers require their employees to take a flu
shot, then less people would t...
Identify the Premises and Conclusion
If all employers require their employees to take a flu
shot, then less people would t...
Identify the Premises and Conclusion
Less than one percent of the people receiving
parking tickets appeal those tickets. T...
Identify the Premises and Conclusion
Less than one percent of the people receiving
parking tickets appeal those tickets. T...
Identify the Premises and Conclusion
Less than one percent of the people receiving
parking tickets appeal those tickets. T...
Write the two arguments presented with the
following statements
You shouldn’t take that job. The pay is lousy, which will
...
Write the two arguments presented with the
following statements
You shouldn’t take that job. The pay is lousy, which will
...
Identify the Premises and Conclusion
You shouldn’t take that job. The pay is lousy, which
will make it hard for you to pay...
The following argument consists of
several conclusions
You spend too much time playing video games. You are not
getting en...
You spend too much time playing video games. You are not
getting enough sleep and your grades are slipping. I think you
ne...
Part 4

Recognizing Good Arguments
1. More Argumentation Key Terms
2. Valid and Invalid Arguments
3. Sound and Unsound Arg...
Recognizing a Good Argument
1. The premises must all be true - or plausible
to a given audience
This is called the The Tru...
Click to View the Linked YouTube Video Below
Argumentation Key Terms
Valid: An argument whose premises logically lead to its
conclusion. To say the argument is valid i...
Valid Argument
A Valid Argument has the following hypothetical
property: If all the premises are true, the
conclusion cann...
Valid Argument
Premise

All actors are robots

Premise

Tom Cruise is an actor

Conclusion

Therefore, Tom Cruise is a rob...
Valid Argument
Premise

Tom is happy only if the Tigers win,

Premise

the Tigers lost;

Conclusion

therefore, Tom is not...
Click to View the Linked YouTube Video Below
Valid Argument Forms
i. If Joe makes this field goal, then Davison
wins
ii. Joe made the field goal .
iii. Therefore the D...
Valid Argument Forms
i. Either the Detroit Tigers or the Giants will
win the World Series.
ii. The Tigers did not win the ...
Valid Arguments
Premise

If a plane is flying it is in the air.

Premise

Flight 999 is flying,

Conclusion

Therefore it ...
Valid Arguments
Premise

If there are clouds in the sky, then rain is
possible.

Premise

No rain is possible.

Conclusion...
Valid Arguments
Premise

Either Elizabeth owns a Honda or she
owns a Saturn.

Premise

Elizabeth does not own a Honda.

Co...
Valid Arguments
Premise

All toasters are items made of gold.

Premise

All items made of gold are time-travel
devices.

C...
Invalid Arguments
Invalid: An argument where the conclusion could be
false even if the premises are true
○ Premise: Steve ...
Invalid Argument Forms
i. Anyone who lives in the city of Davison,
MI also lives in Genesee County.
ii. Frank lives in Gen...
Invalid Argument Forms

i. All smurfs are snorks
ii. All ewoks are snorks
iii. Therefore, All smurfs are
ewoks
Generalizat...
Invalid Arguments- A False Cause
Premise

Every time there is someone in the front
yard, Spot barks.

Premise

Spot is bar...
Invalid Arguments
Premise

All dogs have four legs.

Premise

Francis the Talking Mule is not a dog

Conclusion

Therefore...
Invalid Arguments
Premise

If Obama is president, then a Democrat
is president

Premise

A Democrat is president

Conclusi...
Invalid Arguments
Premise

If my power goes out, then my cable TV
goes out.

Premise

My power is not out,

Conclusion

th...
Invalid Arguments
Premise

If I am with the one I love, then I am
happy.

Premise

I am happy.

Conclusion

Therefore, I a...
FINAL NOTE: Valid or Invalid?
FOR VALID arguments: the addition of extra premises can not
change the conclusion - a valid ...
Spotting Valid and Invalid Arguments
i. If A, then B.
ii. B.
iii. So, A.
i. All monkeys have
blue teeth
ii. Meg is a monke...
i. All OSU fans are
arrogant.
ii. All arrogant people are
dumb.
iii. So, all OSU fans are
dumb.
i. Shermer and Randi are
A...
i. If my astrologer is
clairvoyant, then she
predicted my travel plans
correctly.
ii. She predicted my travel plans
correc...
Unsound Arguments
Unsound: An argument that has at least one false
premise
Example: i. Cows are insects.
ii. Insects are m...
Sound Arguments
Sound: An argument that is valid and contains
only TRUE premises
Example:
i. All cows are mammals.
ii. All...
Valid and Sound Arguments
All athletes are professional golfers

T or F?

Lebron James is an athlete

T or F?

Therefore, ...
Inductive and
Deductive
Reasoning

Part 5:
Deductive Reasoning

A process of reasoning in which
we start with a general rule or conclusion and
look to see whether sp...
Deductive Reasoning
1. What is the conclusion?
2. What evidence supports it?
3. Is that evidence logical?
If you can answe...
Click to View Video on YouTube
Inductive Reasoning

A process of reasoning in which we use small,
specific examples or observation to reach a BIG,
genera...
Inductive Reasoning
When detectives arrive at the scene of a crime, the
first thing they do is look for clues that can hel...
Click to View Video on YouTube
Inductive or Deductive
Inductive: Evidence

Deductive: Conclusion

Conclusion (IEC)

Evidence (DCE)
Inductive or Deductive
If the truth of the premises does not definitely
establishes the truth of the conclusion, but provi...
Inductive or Deductive
1. The Giants have lost their last seven games. Thus, they will
probably lose their next game.
 2. ...
Inductive or Deductive
1. The Giants have lost …Inductive argument – uses 7 specific
examples to reach a bigger conclusion...
Understanding Logical Argumentation, Structure, and Reasoning
Understanding Logical Argumentation, Structure, and Reasoning
Understanding Logical Argumentation, Structure, and Reasoning
Understanding Logical Argumentation, Structure, and Reasoning
Understanding Logical Argumentation, Structure, and Reasoning
Understanding Logical Argumentation, Structure, and Reasoning
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Understanding Logical Argumentation, Structure, and Reasoning

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Understanding Logical Argumentation, Structure, and Reasoning by looking at sample arguments in standard and argument form. With practice exercises for argument analysis and Links to supplemental videos.

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Understanding Logical Argumentation, Structure, and Reasoning

  1. 1. Parts 2-5 Basic Components, Structure and Logic of Argumentation
  2. 2. Part 2 Basic Components of Argumentation
  3. 3. “Master the machinery of [logic], and you have a mental occupation always at hand… that will be of real use to you in any subject you take up. It will give you clearness of thought – the ability to see your way through a puzzle – the habit of arranging your ideas in an orderly and getat-able form – and, more valuable than all, the power to detect fallacies, and to tear to pieces the flimsy illogical arguments, which you will so continually encounter in books, in newspapers, in speeches, and even in sermons, and which so easily delude those who have never taken the trouble to master this fascinating Art. Try it. That is all I ask of you!” -Lewis Carroll
  4. 4. Contents of this Presentation Click below to jump to a section Part 1: Elements of an Argument 1. Key Terms 2. Identifying Conclusions 3. Identifying Premises Part 2: Recognizing Elements of Good Arguments 1. More Key Terms 2. Valid and Invalid Arguments 3. Sound and Unsound Arguments Part 3: Inductive and Deductive Reasoning
  5. 5. Part 1: Elements of an Argument 1. Argumentation Key Terms 2. Identifying Conclusions 3. Identifying Premises
  6. 6. Argumentation Key Terms Claim: a statement or opinion that is either true or false Argument: a claim supported by premises Conclusion: the main claim in an argument Premises: claims that support an argument’s conclusion
  7. 7. Claim Claim: an assertion about the truth, existence, or value of something that is either true or false ❖ Claims are also called Statements or Propositions ❖ When supported by a premises, a claim becomes a conclusion ○ This class is easy. ○ The Detroit Lions have the potential to make the NFL playoffs. ○ This chemical structure is unstable. ○ Democratic socialism is superior to a pure democracy.
  8. 8. Argument Argument: an assertion that contains BOTH a conclusion and premises ○ Not all statements are arguments ○ A statement of fact or opinion based on evidence ○ Some statements contain multiple arguments
  9. 9. Click to View the Linked YouTube Video Below
  10. 10. Which of the following is an argument? Vending machines stocked with soda or candy should be removed from all public schools. ○ NOT AN ARGUMENT. It offers no support Star Wars is the best movie ever. ○ NOT AN ARGUMENT. It offers no support We’d better leave now. If we don’t, we might miss the last train and we’ll be stuck here all night. ○ THIS IS AN ARGUMENT. It offers support (premises) to support the claim.
  11. 11. Conclusions Conclusion: The main claim of an argument that is supported by a premise ○ It’s the logical result of the relationship between the premises. Identifying the Conclusion is the first step in understanding the argument
  12. 12. Click to View the Linked YouTube Video Below
  13. 13. 2 Keys to Identifying the Conclusion 1. Ask, “Is the statement the main point, or is it a claim given to support another statement in the argument 2. Identify the indicator word that often precedes the conclusion, such as: ○ This shows ○ Therefore ○ It follows that ○ Thus ○ This suggests ○ As a Result ○ Hence ○ That's why ○ So ○ Consequently ○ Accordingly ○ This means
  14. 14. Premises Premise: A reason offered as support, or evidence, for another claim. These are often indicated by the words: ○ Because ○ As shown by ○ For ○ Given that ○ As ○ As indicated by ○ Since ○ The reason is that ○ Inasmuch as
  15. 15. Premises Today's freshmen cannot write very well. Joe is a freshman, so he must be a poor writer. Premise Today's freshmen cannot write very well Premise Joe is a freshman, Conclusion so he must be a poor writer.
  16. 16. What is the Conclusion in each of the Following Arguments? Abortion is wrong because all human life is sacred. ❖ Abortion is wrong. It’s flu season and you work with kids, so you should get a flu shot. ❖ You should get a flu shot. We should believe that rocks exist because we are able to see them. ❖ Rocks Exist
  17. 17. What is the Conclusion in each of the Following Arguments? John will probably receive the next promotion since he’ s been here the longest ❖ John will receive the next promotion We must reduce the amount of money we spend on space exploration. Right now, the enemy is launching a massive military buildup, and we need the additional money to purchase military equipment to help match the anticipated increase in the enemy’s strength ❖ We must reduce the amount of money we spend on space exploration.
  18. 18. What is the Conclusion in each of the Following Arguments? It’s a beautiful day. We should go to the park. Besides, I need some exercise. We should go to the park. That movie has had horrible reviews. My sister saw it and said it was boring and her friend spotted three mistakes. Pick a different movie. I am sure we can find something better. We should pick a different movie.
  19. 19. Claim: statement about the truth or value of something that is either true or false Argument: a conclusion and a supporting premise together Conclusion: the main claim or point in an argument that’s supported by premises Premises: pieces of evidence that support the conclusion
  20. 20. CLICK HERE for Practice Identifying the Premises and Conclusions of Arguments
  21. 21. Part 3: Standard Argument Form Identify the Premises and Conclusion
  22. 22. Identify the Premises and Conclusion Rewrite the argument in standard form ● Step 1: Identify which claim is the conclusion. ● Step 2: Identify which claims are premises supporting conclusion Standard Form 1 Premise 1 2 Premise 2 Conclusion
  23. 23. Identify the Premises and Conclusion All black dogs are warm-blooded because they are mammals, and all mammals are warm-blooded Standard Form Premise 1: Premise 2: Conclusion:
  24. 24. Identify the Premises and Conclusion All black dogs are warm-blooded because they are mammals, and all mammals are warm-blooded “because” = indicates a Premise Standard Form Premise 1: Black dogs are mammals Premise 2: All mammals are warm-blooded Conclusion: All black dogs are warm-blooded
  25. 25. Identify the Premises and Conclusion He must be a good basketball player. After all, he’s tall, and all tall people are good basketball players. Standard Form Premise 1: Premise 2: Conclusion:
  26. 26. Identify the Premises and Conclusion He must be a good basketball player. After all, he’s tall, and all tall people are good basketball players. “After all” = indicates a Premise Standard Form Premise 1: He’s tall Premise 2: All tall people are good basketball players Conclusion: He must be a good basketball player
  27. 27. Identify the Premises and Conclusion The weather report is calling for blizzard conditions. Driving could be hazardous. Stay here tonight and you can head back to college after the road is plowed tomorrow. Standard Form Premise 1: Premise 2: Conclusion:
  28. 28. Write it in Standard Form Start on your homework now. You will get done earlier and still have time to watch the movie with us. It shouldn’t take too long and your father can help you if you need it. Standard Form
  29. 29. Identify the Premises and Conclusion If all employers require their employees to take a flu shot, then less people would take sick days. This would result in increased productivity for the nation as a whole. Standard Form Premise 1: Premise 2: Conclusion:
  30. 30. Identify the Premises and Conclusion If all employers require their employees to take a flu shot, then less people would take sick days. This would result in increased productivity for the nation as a whole. Standard Form Premise 1: If all employers require their employees to take a flu shot, then less people would take sick days Premise 2: What is the implied premise? Conclusion: The flu shot would increase productivity for the nation as a whole.
  31. 31. Identify the Premises and Conclusion If all employers require their employees to take a flu shot, then less people would take sick days. This would result in increased productivity for the nation as a whole. Standard Form Premise 1: If all employers require their employees to take a flu shot, then less people would take sick days Premise 2: Less people taking sick days would increase productivity for the nation Conclusion: The flu shot would increase productivity for the nation as a whole.
  32. 32. Identify the Premises and Conclusion Less than one percent of the people receiving parking tickets appeal those tickets. Therefore, one cannot claim that the Parking officers are issuing unwarranted citations. Standard Form Premise 1: Premise 2: Conclusion:
  33. 33. Identify the Premises and Conclusion Less than one percent of the people receiving parking tickets appeal those tickets. Therefore, one cannot claim that the Parking officers are issuing unwarranted citations. Standard Form Premise 1: Less than one percent of the people receiving parking tickets appeal those tickets. Premise 2: What is the implied premise? Conclusion: one cannot claim that the Parking officers are issuing unwarranted citations.
  34. 34. Identify the Premises and Conclusion Less than one percent of the people receiving parking tickets appeal those tickets. Therefore, one cannot claim that the Parking officers are issuing unwarranted citations. Standard Form Premise 1: Less than one percent of the people receiving parking tickets appeal those tickets. Premise 2: People appeal unwarranted citations Conclusion: one cannot claim that the Parking officers are issuing unwarranted citations.
  35. 35. Write the two arguments presented with the following statements You shouldn’t take that job. The pay is lousy, which will make it hard for you to pay your bills, and that will make you unhappy. Main Argument Premise 1: Premise 2: Conclusion: Secondary Argument Premise 1: Premise 2: Conclusion:
  36. 36. Write the two arguments presented with the following statements You shouldn’t take that job. The pay is lousy, which will make it hard for you to pay your bills, and that will make you unhappy. Main Argument Premise 1: The lousy pay of that job will make it hard for you to pay your bills Premise 2: Not being able to pay your bills will make you unhappy Conclusion: You shouldn’t take that job Secondary Argument Premise 1: it hard for you to pay your bills Premise 2: Not being able to pay your bills Conclusion: It will make you unhappy
  37. 37. Identify the Premises and Conclusion You shouldn’t take that job. The pay is lousy, which will make it hard for you to pay your bills, and that will make you unhappy. Main Argument Premise 1: The lousy pay of that job will make it hard for you to pay your bills Premise 2: Not being able to pay your bills will make you unhappy Conclusion: You shouldn’t take that job
  38. 38. The following argument consists of several conclusions You spend too much time playing video games. You are not getting enough sleep and your grades are slipping. I think you need to change your daily routine. Make a list of your priorities. If you don’t, I think you’re headed for big trouble. Write the claims in standard form in the chart on the next slide. 1. You may have multiple conclusions 2. Support each conclusion with at least one premise written above it. 3. Some claims may support multiple conclusions. 4. Write as many standard argument forms as needed.
  39. 39. You spend too much time playing video games. You are not getting enough sleep and your grades are slipping. I think you need to change your daily routine. Make a list of your priorities. If you don’t, I think you’re headed for big trouble.
  40. 40. Part 4 Recognizing Good Arguments 1. More Argumentation Key Terms 2. Valid and Invalid Arguments 3. Sound and Unsound Arguments
  41. 41. Recognizing a Good Argument 1. The premises must all be true - or plausible to a given audience This is called the The Truth Condition 2. The conclusion must logically follow from the premises This is called the The Logic Condition
  42. 42. Click to View the Linked YouTube Video Below
  43. 43. Argumentation Key Terms Valid: An argument whose premises logically lead to its conclusion. To say the argument is valid is to say that it is logically impossible for its premises to be true and its conclusion false. Invalid: If an argument is invalid, then it is possible for the conclusion to be false even if all the premises are true. Unsound: An argument that has at least one false premise Sound: An argument that is valid and contains only TRUE premises Inductive Reasoning: A process of reasoning in which we use small, specific examples or observation to reach a BIG, general rule, conclusion or theory Deductive Reasoning: A process of reasoning in which we start with a general rule or conclusion and look to see whether specific evidence supports, or fits, that previously held belief
  44. 44. Valid Argument A Valid Argument has the following hypothetical property: If all the premises are true, the conclusion cannot be false. That is, if you were to imagine that all the premises were true, then it would be logically impossible for the conclusion false at the same time Logic guarantees of the truth of the conclusion, (now provided that the premises are true)
  45. 45. Valid Argument Premise All actors are robots Premise Tom Cruise is an actor Conclusion Therefore, Tom Cruise is a robot Premise If Michigan scores the most points then they win the game. Premise Michigan scored more points. Conclusion So, Michigan won the game
  46. 46. Valid Argument Premise Tom is happy only if the Tigers win, Premise the Tigers lost; Conclusion therefore, Tom is not happy. The Argument Form is... If A then B A Therefore, B When we say "If A then B" it means that, every time, if A is true or false, then B is true or false also.
  47. 47. Click to View the Linked YouTube Video Below
  48. 48. Valid Argument Forms i. If Joe makes this field goal, then Davison wins ii. Joe made the field goal . iii. Therefore the Davison won. If P then Q i. If the patient has malaria, then a blood test will indicate that his blood harbors the P. vivax virus ii. Blood test indicate that the patient’s blood does not harbor the P. vivax virus. iii. Therefore the patient does not have malaria. If P then Q P Therefore Q Not Q Therefore Not P
  49. 49. Valid Argument Forms i. Either the Detroit Tigers or the Giants will win the World Series. ii. The Tigers did not win the Word Series iii. Therefore, the Giants won Either P or Q i. If John gets a raise, then he will buy a house. ii. If John buys a house, he'll run for city council. iii. Therefore, if John gets a raise, he will run for a position on the city council If P then Q Not P Therefore Q If Q then R Therefore ... If P then R
  50. 50. Valid Arguments Premise If a plane is flying it is in the air. Premise Flight 999 is flying, Conclusion Therefore it is in the air. Premise If P then Q Premise P Conclusion Therefore, Q
  51. 51. Valid Arguments Premise If there are clouds in the sky, then rain is possible. Premise No rain is possible. Conclusion Therefore, there are no clouds in the sky Premise If P then Q Premise Not Q Conclusion Therefore, Not P
  52. 52. Valid Arguments Premise Either Elizabeth owns a Honda or she owns a Saturn. Premise Elizabeth does not own a Honda. Conclusion Therefore, Elizabeth owns a Saturn. Premise Either P or Q Premise Not P Conclusion Therefore, Q
  53. 53. Valid Arguments Premise All toasters are items made of gold. Premise All items made of gold are time-travel devices. Conclusion Therefore, all toasters are time-travel devices. Premise All P are Q Premise All Q are R Conclusion Therefore, All P are R
  54. 54. Invalid Arguments Invalid: An argument where the conclusion could be false even if the premises are true ○ Premise: Steve owns a Lexus automobile. ○ Premise: Rich people own Lexus automobiles ○ Conclusion: Therefore, Steve must be rich The Argument Form is... ● P is Q ● R is Q ● Therefore, P is R
  55. 55. Invalid Argument Forms i. Anyone who lives in the city of Davison, MI also lives in Genesee County. ii. Frank lives in Genesee County. iii. Therefore, Frank lives in the city Davison, MI. If P, then Q. Q Therefore, P Generalization i. Anyone who lives in the city of Davison, MI also lives in Genesee County. ii. Frank does not live in the city Davison, MI. iii. Therefore, Frank does not live in Genesee County. If P, then Q. Not P. Therefore, not Q. Generalization
  56. 56. Invalid Argument Forms i. All smurfs are snorks ii. All ewoks are snorks iii. Therefore, All smurfs are ewoks Generalizations All P are Q All R are Q Therefore, P are R i. Either you’re with me or you’ X or Y re against me. not X ii. You’re not with me. Therefore, Y iii. So, you must be against me. False Dichotomy
  57. 57. Invalid Arguments- A False Cause Premise Every time there is someone in the front yard, Spot barks. Premise Spot is barking, Conclusion so someone must be in the front yard Premise If X then Y Premise Y Conclusion Therefore, X
  58. 58. Invalid Arguments Premise All dogs have four legs. Premise Francis the Talking Mule is not a dog Conclusion Therefore, Francis the Talking Mule does not have four legs Premise All X are Y Premise not X Conclusion Therefore, Not Y
  59. 59. Invalid Arguments Premise If Obama is president, then a Democrat is president Premise A Democrat is president Conclusion Therefore, Obama is president Premise If X then Y Premise Y Conclusion Therefore, X
  60. 60. Invalid Arguments Premise If my power goes out, then my cable TV goes out. Premise My power is not out, Conclusion therefore, my cable TV is not out. Premise If X then Y Premise not X Conclusion Therefore, Not Y
  61. 61. Invalid Arguments Premise If I am with the one I love, then I am happy. Premise I am happy. Conclusion Therefore, I am with the one I love Premise If X then Y Premise Y Conclusion Therefore, X
  62. 62. FINAL NOTE: Valid or Invalid? FOR VALID arguments: the addition of extra premises can not change the conclusion - a valid conclusion reached from a set of premises can never be changed by the addition of new premises. Also, it is impossible for the premises of a valid argument to be true and the conclusion to be false FOR INVALID arguments: the addition of new premises will many times strengthen or weaken a given conclusion. Also, it is possible for the conclusion of an invalid argument to be false even if it has true premises.
  63. 63. Spotting Valid and Invalid Arguments i. If A, then B. ii. B. iii. So, A. i. All monkeys have blue teeth ii. Meg is a monkey iii. Therefore Meg has blue teeth
  64. 64. i. All OSU fans are arrogant. ii. All arrogant people are dumb. iii. So, all OSU fans are dumb. i. Shermer and Randi are Arabic. ii. Shermer and Randi are cops iii. So, some Arabs are cops.
  65. 65. i. If my astrologer is clairvoyant, then she predicted my travel plans correctly. ii. She predicted my travel plans correctly. iii. So, my astrologer is clairvoyant. i. If God created the universe, we should observe order and design in Nature. ii. We do observe order and design in Nature. iii. So, God created the universe.
  66. 66. Unsound Arguments Unsound: An argument that has at least one false premise Example: i. Cows are insects. ii. Insects are mammals. iii. So cows are mammals. Example: i. All dogs have 5 legs. ii. Fido is a dog. iii. Therefore Fido has 5 legs
  67. 67. Sound Arguments Sound: An argument that is valid and contains only TRUE premises Example: i. All cows are mammals. ii. All mammals are animals. iii. So cows are animals.
  68. 68. Valid and Sound Arguments All athletes are professional golfers T or F? Lebron James is an athlete T or F? Therefore, Lebron James is a professional golfer T or F? All humans are whales T or F? All whales are mammals T or F? So, all humans are mammals T or F? All Detroit Lions are football players T or F? Calvin Johnson is a football players T or F? Therefore, Calvin Johnson is a Detroit Lion T or F?
  69. 69. Inductive and Deductive Reasoning Part 5:
  70. 70. Deductive Reasoning A process of reasoning in which we start with a general rule or conclusion and look to see whether specific evidence supports, or fits, that previously held belief
  71. 71. Deductive Reasoning 1. What is the conclusion? 2. What evidence supports it? 3. Is that evidence logical? If you can answer yes to question 3, then the conclusion should be logical and the argument valid and sound. Many deductive arguments are valid
  72. 72. Click to View Video on YouTube
  73. 73. Inductive Reasoning A process of reasoning in which we use small, specific examples or observation to reach a BIG, general rule, conclusion or theory
  74. 74. Inductive Reasoning When detectives arrive at the scene of a crime, the first thing they do is look for clues that can help them piece together what happened. 1. What have you observed? What evidence is available? 2. What can you conclude from that evidence? 3. Is that conclusion logical? Many Inductive arguments are strong but invalid
  75. 75. Click to View Video on YouTube
  76. 76. Inductive or Deductive Inductive: Evidence Deductive: Conclusion Conclusion (IEC) Evidence (DCE)
  77. 77. Inductive or Deductive If the truth of the premises does not definitely establishes the truth of the conclusion, but provides a strong reason to believe the conclusion true, then you have an inductive argument If the truth of the premises definitely establishes the truth of the conclusion then you have a valid deductive argument
  78. 78. Inductive or Deductive 1. The Giants have lost their last seven games. Thus, they will probably lose their next game.  2. If you brush and floss your teeth daily then you will have fewer cavities. Marie brushes and flosses her teeth daily. Thus, she will have fewer cavities.  3. Jones will play tennis today if Smith plays. Jones will not play tennis today. Therefore, Smith will not play.  4. 4 out of 5 times I beat Corey at pool and I'm going to play him tomorrow. So, I'll very likely win. 5. No man has ever gotten pregnant. Therefore, no man ever will get pregnant.
  79. 79. Inductive or Deductive 1. The Giants have lost …Inductive argument – uses 7 specific examples to reach a bigger conclusion 2.  If you brush and floss your teeth …Deductive argument – states the broadly accepted research and reaches a specific conclusion 3.  Jones will play tennis today if …Deductive argument –gives an overarching rule that governs the behavior to predict a specific outcome 4.  4 out of 5 times I beat Corey…Inductive argument – uses specific examples to predict the conclusion 5. No man has ever gotten pregnant…Inductive argument – the conclusion is a BIG, overarching rule based on numerous specific examples to date. More Practice Here
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