Deductive and Inductive Reasoning

F.O.A. (Bellwork)

Mr. Ezzell is a man. Men like to watch football. Therefore, …. You fill in the blank. Mrs. Ezzell is a woman. Women like to shop. Therefore, …. You fill in the blank. Turn in signed test

Classwork (continued)

Finish questions 1-6 on page 1,011

Video

Write down the definition for inductive reasoning.

Think of an example for inductive reasoning.

Write down the definition of deductive reasoning.

Think of an example for deductive reasoning.

Key Terms…

Deductive- an argument whose conclusion is certain

Inductive- an argument whose conclusion is likely

Premise- a reason offered as support for a claim

Example

All men are messy.(–premise) Coach Long is a man.(– premise) Therefore Coach Long must be messy.

(--conclusion)

Let’s try one…

Smith owns only blue and brown pants. Smith is wearing a pair of his pants today. Therefore…

This is a deductive argument because the first two premises prove the last sentence must be true.

The soccer game is either on Thursday or Friday.

I just found out that the game is not on Thursday.

So the game must be on __________

Is this deductive?

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January has always been cold in Siberia. Today is January 14. It will be another cold day in Siberia.

This argument is inductive. It is likely but not guaranteed.

The local branch of Wachovia Bank was robbed yesterday. Jenny needed money to pay off her debts. She just bought a gun two days ago, and I saw her hanging around the local Wachovia bank yesterday morning. Today the people she owed money to stopped looking for her. So Jenny must have robbed that bank.

If you have ever seen an episode of Law & Order you know that they prove issues like this to be wrong so this is _______ reasoning.

Deductive (based on laws, rules, & things known)

All dogs are mammals. All mammalshave kidneys. Therefore, all dogs havekidneys.

Inductive (based on an observation):All dogs that we have seen are white;therefore the next dog we see will bewhite.

Deductive (based on facts, laws, rules):All squares are rectangles and allrectangles have four sides. So all squaresmust have four sides.

Inductive (based on observations):Since Chris is a good athlete, his sistermust be a good athlete, too.

Emily’s shirt is red. My’kia is wearing a

red shirt. Malik’s shirt is also red.

Therefore, the next person I see will be

wearing a red shirt.

I noticed that every time I spent more than two hours on the computer, my head hurt. I’ve been on the computer for a while and my head hurts, so I must have been on for more than two hours.

Dairy products ruin if left out of the refrigerator overnight. Cristian left his yogurt on the counter overnight, so it is ruined.

According to the LMS discipline policy, if a student is disrespectful to a teacher, they receive a dean referral. Anthony was disrespectful to his teacher, so he will receive a dean referral.

1. Nails puncture bike tires. If you run over that nail, your tire will pop.

2. Dairy products ruin if left out overnight. Al left his yogurt on the counter overnight, so it is bad.

3. Every time I buy a bag of Hot Cheetos from the cafeteria, it is only half full. I guess if I buy a bag today, it will be half full, too.

4. Wasps have stingers. Be careful! That wasp might sting!

5. The baseball coach sees that the opposing batter hits fast-balls well, so he instructs his pitcher not to throw a fast-ball.

Apples turn brown when cut and left out. Bananas turn brown when cut and left out. That must mean that apples are bananas.

Does this have a false premise? Hint: Look at the 1st two statements. Is one of those false?

Apples are red. Santa’s suit is red. Apples and Santa’s suit must both be fruits.

Women hate sports. Mrs. Ruis is a woman. So, she must hate sports.

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