Drawing Conclusions

Inductive and Deductive Reasoning

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Objective

• Through the study of existing arguments, the student will be able to identify a premise, claim, and conclusion and demonstrate understanding by classifying examples as inductive or deductive.

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Why do I need to know this?

• You need to be able to construct effective arguments

• You need to be able to evaluate the argument of others so as to not fall for it

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You don’t know you know this.

• 2, 4, 6, 8, ____

• 2+4= _____

• If map becomes mapping and run becomes running, then yit becomes…

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What’s the difference in their thought processing?

• Jalen said, “I've noticed that every time I kick a ball up, it comes back down, so I guess this next time when I kick it up, it will come back down, too.”

• Emily said, “That's Newton's Law. Everything which goes up must come down. And so, if you kick the ball up, it must come down.”

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Parts of an Argument

• Claim – a statement about the truth, existence, or value of something

• Premise – the evidence used to support a conclusion or claim

• Conclusion – the main claim or point of an argument

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For example…• When detectives arrived at the scene

of the robbery, they began looking for clue to piece together the story of what happened. The broken window suggested entrance because the glass was on the inside. The only disturbance in the office was a painting which hid a safe. This suggests the person knew the safe was there. If the location of the hidden safe was known, the criminal must have known the victim.

Ask yourself…1. What is the

conclusion made in this example?

2. What evidence supports that claim?

3. Label the premise(s) and the conclusion.

4. Does the evidence come first or does the conclusion come first?

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CHECK OUT THIS VIDEO TO FIND THE CLAIM AND THE PREMISES.

Video 1: House

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Two Major Reasoning Types

Inductive• I take IN the observation

and draw a conclusion.• Think: I = INFERENCE!• Moves from general

observations to specific conclusions.

Deductive• I DRAW a conclusion and

look for facts/evidence to prove I’m right.

:: hint, hint ::

• Deductive involves an assumed truth or fact.

• Inductive involves a pattern and what could happen.

General to specific ideas.

Test questions will require identifying not only deductive, but deductive and logical.

Specific to general ideas.

Considered the least reliable reasoning, test questions will require identifying inductive or deductive.

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Inductive or Deductive?• When detectives arrived at the scene

of the robbery, they began looking for clue to piece together the story of what happened. The broken window suggested entrance because the glass was on the inside. The only disturbance in the office was a painting which hid a safe. This suggests the person knew the safe was there. If the location of the hidden safe was known, the criminal must have known the victim.

Ask yourself…1. What is the

conclusion made in this example?

2. What evidence supports that claim?

3. Label the premise(s) and the conclusion.

4. Does the evidence come first or does the conclusion come first?

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Inductive or Deductive?• When detectives arrived at the scene

of the robbery, they began looking for clue to piece together the story of what happened. The broken window suggested entrance because the glass was on the inside. The only disturbance in the office was a painting which hid a safe. This suggests the person knew the safe was there. If the location of the hidden safe was known, the criminal must have known the victim.

Ask yourself…1. What is the

conclusion made in this example?

2. What evidence supports that claim?

3. Label the premise(s) and the conclusion.

4. Does the evidence come first or does the conclusion come first?

INDUCTIVE!Observations were made and the conclusion was

based on what the detective observed at the scene.

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Recap: Inductive Reasoning• Induction moves from ______ to _______, or

is when a person uses ___________ to draw a ____________.

• But, the conclusion is based on observation and patterns and may not be logical.

• You may ask yourself…– What has been observed? What is the evidence?– What can be concluded?– Is the conclusion logical or illogical?

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So think about it…Specific Situation

Hasty Generalization

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Model: Can you use induction?

• Young children read comic strips.• Teenagers read comic strips.• Adults read comic strips.• _________________________.

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Your turn to use induction!

• The beach roads are jammed with traffic every Memorial Day.

• The beach roads are jammed with traffic every July 4th.

• The beach roads are jammed with traffic every Labor Day.

• _________________________.

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Model: I doThink: How is this inductive?• Every time I go to Wal-Mart, I end up buying

more than I planned. This time I made a list and planned to spend $25 when I actually spent $50. I must have needed more than I thought.

• Evidence from past experience, evidence from current trip, conclusion. Is it logical?– No. There is no evidence to suggest I needed the

extra items. My list included things I knew I needed.

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Model: We doThink: How is this inductive?• I got a new pair of Beat headphones for

Christmas. Every time I listen to my favorite album, it sounds funny. I think the headphones have something wrong with them.

• Stated fact, evidence from experience, conclusion. Is it logical?– Yes. If it sounds right on other devices, the

problem is most likely in the device.

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Model: We doThink: How is this inductive?• For the last six months, I have gone to the spa

for a massage. My therapist says I should drink water afterward, but I don’t. I started to notice I get headaches after the massages when I don’t drink water. Not drinking water must be a serious health concern.

• Evidence, evidence, evidence, conclusion. Is it logical?– No. People do drink things which are not water

and are fine, so I can’t say not drinking water is a serious health concern.

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Deductive Reasoning• Deduction moves from _______ to ________,

or is when a ____________ is given with ___________ to support it.

• Must see if the evidence is valid. If the evidence is valid, the conclusion must be logical.

• You may ask yourself…– What is the conclusion?– What evidence supports it?– Is the evidence logical?

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So think about it…

General Assumed Law/Truth

Premise: EvidenceSpecific Conclusion

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Parts of Deduction• Syllogism - form of deductive reasoning made up

of three parts: a major premise, a minor premise, and a conclusion.

• Premise - general or universal statement which is said to be true.

• Major Premise - must make a universal statement. This means it must be true of all, every, no, or none of the people, objects, or events that are the subject of the statement.

• Minor Premise - fact or truth stated must be related to the major premise.

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Valid or Invalid?

• Valid argument – an argument resulting from a premise which is sound

• Non-valid argument – an argument resulting from a false premise

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Think about it…

DCE Can come with separate evidence or continuous evidence.• You shouldn’t take the job. The pay is

lousy, it has terrible hours, and there are no benefits.

• You shouldn’t take the job. The pay is lousy which will make it hard to pay your bills which will make you unhappy.

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Model: Can you use deductive reasoning?• All lawyers must pass a bar exam.• Barbara Smith is a lawyer.• _________________________.

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Your turn to use deductive reasoning!

• All ninth graders must take English I.• Sarah is a ninth grader.• _________________________.

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Model: I doThink: How is this deductive?• Taking a person’s life is always wrong.

Capital punishment involves taking a person’s life. Therefore, capital punishment is always wrong.

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Model: We doThink: How is this deductive?• All snakes are cold-blooded.• All snails are cold-blooded.• Snakes and snails are the same thing.

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Model: We doThink: How is this deductive?• Every human being has rights. John is a

human being; therefore, John has rights.

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Think you’ve got it?• What are the parts of any argument?• What is inductive reasoning?• Once finding an argument is inductive,

what must you consider?• What is deductive reasoning?• What are the key components of

deductive reasoning?• Once finding an argument is deductive,

what must you consider?

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Watch the Model

• Think aloud questions:–What is the conclusion?– Is it based on facts or observations?– Is the conclusion definitely true?–Would more evidence make the conclusion

more believable?–What type of reasoning is this?

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Inductive or Deductive?• Mrs. Jones is the principal of a middle school which

is struggling with high absenteeism. Before deciding on a plan of action to improve attendance, she begins by studying the monthly attendance reports. She also examines excuse notes students have brought. Then she gathers data from teachers and parents about why students are absent. Finally, she writes a report explaining her findings and offering suggestions for improving the problem.

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Inductive or Deductive?• Mrs. Jones is the principal of a middle school which

is struggling with high absenteeism. Before deciding on a plan of action to improve attendance, she begins by studying the monthly attendance reports. She also examines excuse notes students have brought. Then she gathers data from teachers and parents about why students are absent. Finally, she writes a report explaining her findings and offering suggestions for improving the problem.

This is an example of inductive reasoning. Notice that Mrs. Jones is gathering facts and data (monthly attendance reports, excuse notes, parent and teacher feedback and data) before she writes the report, so she is going from the specific pieces of information to the general conclusion.

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Inductive or Deductive?• Jim is a 9th grader at a very strict private school. His

class is taking a field trip tomorrow. Since they will be going to the park after touring the Parthenon, Jim would like to wear athletic shorts. When he asks his teacher if that would be alright, she consults the dress code section of the student handbook. She discovers that it says students are allowed to wear athletic shorts only during P.E. She then tells Jim that he will not be allowed to wear the athletic shorts on the field trip.

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Inductive or Deductive?• Mrs. Jones is the principal of a middle school which

is struggling with high absenteeism. Before deciding on a plan of action to improve attendance, she begins by studying the monthly attendance reports. She also examines excuse notes students have brought. Then she gathers data from teachers and parents about why students are absent. Finally, she writes a report explaining her findings and offering suggestions for improving the problem.

This is an example of deductive reasoning because the teacher consults the student handbook (the overarching guide for dress code) before arriving at a conclusion regarding whether or not Jim will be allowed to wear athletic shorts on the field trip. She is moving from the general/universal statement to the specific, more limited statement.

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SO HOW IS THIS TESTED?

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On the EOC…

• Questions will give a conclusion and evidence

• You determine inductive or deductive• You determine logical/illogical or

valid/invalid• May also ask to identify premises

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another LAME memory trick!

Inductive = Evidence to Conclusion

Deductive = Conclusion to Evidence

Starts with a Vowel

Starts with a Vowel

Starts with a Consonant

Starts with a Consonant

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Help me think through this example…

Which of the following claims would be best expressed by inductive reasoning?

A. Your first quiz grade usually indicates how you will do in the course.

B. The final exam accounts for 30% of the course grade.

C. Late papers will not be accepted.D. Gravity’s Rainbow is required reading

in your course.

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Which of the following claims would be best expressed by inductive reasoning?

A. Your first quiz grade usually indicates how you will do in the course.

B. The final exam accounts for 30% of the course grade.

C. Late papers will not be accepted.D. Gravity’s Rainbow is required reading

in your course.

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Model: I do

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Model: We do

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Closure: Do you have it?• Recap:

– Who can summarize our learning?– How does this connect to what we have been learning? To

life outside of the classroom?• Apply the Skills on your Exit Ticket!

– What is the conclusion?– Is it based on facts or observations?– Is the conclusion definitely true?– Would more evidence make the conclusion more

believable?– What type of reasoning is this?