1. …and comparison to Deductive Reasoning
Inductive Reasoning
…and comparison to Deductive Reasoning

2. Inductive reasoning
The process of determining general principles by logic or observation from specific data; reasoning from parts to whole (e.g., all ice I’ve ever felt is cold; therefore, all ice is cold)
In other words, the process of reasoning from the specific to the general

3. Inductive Reasoning
When writers make inductive arguments, they present a series of examples and argue that these examples justify the conclusions they have drawn. Take a look at the following examples:

4. Every tornado I have ever seen in the United States rotated counterclockwise, and I have seen dozens of them.
We see a tornado in the distance, and we are in the United States.
I conclude that the tornado we see right now must be rotating counterclockwise.

5. Jennifer leaves for school at 7:00 a.m.
Jennifer is always on time.
Jennifer assumes, then, that she will always be on time if she leaves at 7:00 a.m.

6. I never see my friend Marty without a cigarette or a cigar
I never see my friend Marty without a cigarette or a cigar. When we go out, he drinks more than anybody else in our group. If I go by his house on Saturday mornings, he opens the door with a beer in his hand. He eats junk food constantly; his car is littered with smelly pizza boxes, hamburger wrappers, and empty soda cans. I think Marty’s lifestyle is very unhealthy; he is going to die prematurely of a heart attack or end up in rehab for his addictions.

7. Inductive reasoning only deals with degrees of certainty
Inductive reasoning only deals with degrees of certainty. While Marty definitely has an unhealthy lifestyle, the speaker should change the second part of her conclusion to speculation rather certainty: If he keeps living like this, Marty is more likely to die of a premature heart attack or end up in rehab.

8. Deductive vs. Inductive Reasoning
Deductive Reasoning follows this pattern:
You already have a broad theory and are seeking to apply it to individual observations. Deductive arguments are strictly valid or invalid.

9. Inductive Reasoning looks more like this:
You are forming a broad theory based on multiple individual observations. Inductive arguments can be more or less accurate, but not 100% valid or invalid.

10. You’ll notice this looks pretty similar to the scientific method:
Inductive reasoning is used when generating hypotheses, formulating theories and discovering relationships, and is essential for scientific discovery.
Deductive reasoning, meanwhile, can be used to test or apply an existing theory to new circumstances.

11. Let’s practice determining if arguments are deductive or inductive:
The figure he drew has only three sides, so it isn’t a square.
A) Deductive B) Inductive

12. Let’s practice determining if arguments are deductive or inductive:
The figure he drew has only three sides, so it isn’t a square.
A) Deductive B) Inductive
ANSWER: A

13. Deductive or Inductive?
It was the pizza that made my stomach churn. What else could it be? I was fine until I ate it.
A) Deductive B) Inductive

14. Deductive or Inductive?
It was the pizza that made my stomach churn. What else could it be? I was fine until I ate it.
A) Deductive B) Inductive
ANSWER: B

15. Deductive or Inductive?
It’s wrong to hurt someone’s feelings, and that is exactly what you are doing when you speak to me like that.
A) Deductive B) Inductive

16. Deductive or Inductive?
It’s wrong to hurt someone’s feelings, and that is exactly what you are doing when you speak to me like that.
A) Deductive B) Inductive
ANSWER: A

17. Deductive or Inductive?
Either Colonel Mustard or Reverend Green killed Professor Plum. But whoever ran off with Mrs. White did not kill the professor. Since Reverend Green ran off with Mrs. White, Colonel Mustard killed professor plum.
A) Deductive B) Inductive

18. Deductive or Inductive?
Either Colonel Mustard or Reverend Green killed Professor Plum. But whoever ran off with Mrs. White did not kill the professor. Since Reverend Green ran off with Mrs. White, Colonel Mustard killed professor plum.
A) Deductive B) Inductive
ANSWER: A

19. Deductive or Inductive?
I’ve never met a golden retriever with a nasty disposition. I bet there aren’t any.
A) Deductive B) Inductive

20. Deductive or Inductive?
I’ve never met a golden retriever with a nasty disposition. I bet there aren’t any.
A) Deductive B) Inductive
ANSWER: B

21. Deductive or Inductive?
Since some grapes are purple, and all grapes are fruit, some fruit is purple. A) Deductive B) Inductive

22. Deductive or Inductive?
Since some grapes are purple, and all grapes are fruit, some fruit is purple.
Deductive B) Inductive
ANSWER: A

23. Deductive or Inductive?
Why is Sarah so mean to Janice? The only thing I can think of is that she’s jealous. Jealousy is what’s making her mean.
A) Deductive B) Inductive

24. Deductive or Inductive?
Why is Sarah so mean to Janice? The only thing I can think of is that she’s jealous. Jealousy is what’s making her mean.
A) Deductive B) Inductive
ANSWER: B

25. Deductive or Inductive?
Obama will make a fine president. After all, he made a fine senator.
A) Deductive B) Inductive

26. Deductive or Inductive?
Obama will make a fine president. After all, he made a fine senator.
A) Deductive B) Inductive
ANSWER: B