understanding logical argumentation, structure, and reasoning
DESCRIPTION
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.TRANSCRIPT
Basic Components, Structure and Logic of
Argumentation
Parts 2-5
Basic Components of Argumentation
Part 2
“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 get-
at-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
Part 1: Elements of an Argument1. Key Terms2. Identifying Conclusions3. Identifying Premises
Part 2: Recognizing Elements of Good Arguments1. More Key Terms2. Valid and Invalid Arguments3. Sound and Unsound Arguments
Part 3: Inductive and Deductive Reasoning
Contents of this PresentationClick below to jump to a section
Part 1: Elements of an Argument
1. Argumentation Key Terms2. Identifying Conclusions3. Identifying Premises
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
Argumentation Key Terms
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.
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
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 schools.
Star Wars is the best movie ever.
We’d better leave now. If we don’t, we might miss
the last train and we’ll be stuck here all night.
○ NOT AN ARGUMENT. It offers no support
○ NOT AN ARGUMENT. It offers no support
○ THIS IS AN ARGUMENT. It offers support
(premises) to support the claim.
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
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 statement in the argument
2. Identify the indicator word that often precedes
the conclusion, such as:
○ Therefore
○ Thus
○ As a Result
○ That's why
○ Consequently
○ This means
○ This shows
○ It follows that
○ This suggests
○ Hence
○ So
○ Accordingly
Premises
Premise: A reason offered as support, or
evidence, for another claim.
These are often indicated by the words:
○ Because
○ For
○ As
○ Since
○ Inasmuch as
○ As shown by
○ Given that
○ As indicated by
○ The reason is that
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.
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
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.
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.
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
CLICK HEREfor 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 conclusion.● Step 2: Identify which claims are premises supporting
conclusion
Standard Form1 Premise 1
2 Premise 2
Conclusion
Identify the Premises and Conclusion
All black dogs are warm-blooded because they are mammals, and all mammals are warm-blooded
Standard FormPremise 1:
Premise 2:
Conclusion:
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 FormPremise 1: Black dogs are mammals
Premise 2: All mammals are warm-blooded
Conclusion: All black dogs are warm-blooded
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 FormPremise 1:
Premise 2:
Conclusion:
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 FormPremise 1: He’s tallPremise 2: All tall people are good basketball players
Conclusion: He must be a good basketball player
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 FormPremise 1:
Premise 2:
Conclusion:
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
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 FormPremise 1:
Premise 2:
Conclusion:
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 FormPremise 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.
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 FormPremise 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.
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:
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.
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 citationsConclusion: one cannot claim that the Parking officers are
issuing unwarranted citations.
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.
Secondary ArgumentPremise 1:
Premise 2:
Conclusion:
Main ArgumentPremise 1:
Premise 2:
Conclusion:
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.
Secondary ArgumentPremise 1: it hard for you to pay your bills
Premise 2: Not being able to pay your bills
Conclusion: It will make you unhappy
Main ArgumentPremise 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
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 ArgumentPremise 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
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.
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.
Part 4
Recognizing Good Arguments
1. More Argumentation Key Terms2. Valid and Invalid Arguments3. Sound and Unsound Arguments
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
Click to View the Linked YouTube Video Below
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
Argumentation Key Terms
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)
Valid Argument
Premise If Michigan scores the most points then they win the game.
Premise Michigan scored more points.
Conclusion So, Michigan won the game
Premise All actors are robots
Premise Tom Cruise is an actor
Conclusion Therefore, Tom Cruise is a robot
Valid Argument
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.
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
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 Davison won.
If P then Q
P
Therefore 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
Not Q
Therefore
Not P
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
Not P
Therefore 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
If Q then R
Therefore ...
If P then R
Premise If a plane is flying it is in the air.
Premise Flight 999 is flying,Conclusion Therefore it is in the air.
Valid Arguments
Premise If P then Q
Premise PConclusion Therefore, Q
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
Valid Arguments
Premise If P then Q
Premise Not QConclusion Therefore, Not P
Premise Either Elizabeth owns a Honda or she owns a Saturn.
Premise Elizabeth does not own a Honda.Conclusion Therefore, Elizabeth owns a Saturn.
Valid Arguments
Premise Either P or Q
Premise Not PConclusion Therefore, Q
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.
Valid Arguments
Premise All P are Q
Premise All Q are RConclusion Therefore, All P are R
Invalid ArgumentsInvalid: 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
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, PGeneralization
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
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’re against me.
ii. You’re not with me.iii. So, you must be against me.
False Dichotomy
X or Y
not X
Therefore, Y
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
Invalid Arguments- A False Cause
Premise If X then Y
Premise YConclusion Therefore, X
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
Invalid Arguments
Premise All X are Y
Premise not XConclusion Therefore, Not Y
Premise If Obama is president, then a Democrat is president
Premise A Democrat is president
Conclusion Therefore, Obama is president
Invalid Arguments
Premise If X then Y
Premise YConclusion Therefore, X
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.
Invalid Arguments
Premise If X then Y
Premise not XConclusion Therefore, Not Y
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
Invalid Arguments
Premise If X then Y
Premise YConclusion Therefore, X
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.
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 monkeyiii. Therefore Meg has
blue teeth
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.
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.
Unsound ArgumentsUnsound: 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
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.
Valid and Sound ArgumentsAll 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?
Inductive and Part 5:Deductive Reasoning
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
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
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, general rule, conclusion or theory
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
Click to View Video on YouTube
Inductive or Deductive
Inductive: Evidence Conclusion (IEC)
Deductive: Conclusion Evidence (DCE)
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
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.
Inductive or Deductive1. 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