1. Using Inductive Arguments

2. Inductive Arguments
Move from specific examples or facts to a general conclusion
Opposite of deduction (syllogisms)
No distinctive form
BUT there is a process to follow

3. Induction - Process 1) Decide on a question to be answered
Or a tentative answer to a question (hypothesis)
2) Gather evidence
3) Move from evidence to conclusion by making an inference

4. Inference A statement about the unknown based on the known
Answers the question
Takes all evidence into account

5. Inductive process: example (557)
Question: How did that living-room window get broken?
Evidence:
There is a baseball on the living-room floor.
The baseball was not there this morning

6. Inductive process (cont’d)
Evidence: (cont’d)
Some children were playing baseball this afternoon
They were playing in the vacant lot across from the window.
They stopped playing a little while ago.
They aren’t in the vacant lot now.

7. Inductive process (cont’d)
Conclusion: One of the children hit or threw the ball through the window; then, they all ran away.

8. Induction: Problems
One additional piece of evidence can make the conclusion doubtful
Ex: children were playing volleyball, not baseball
Result? True answer can’t be inferred

9. Induction: Problems (cont’d)
Even if conclusion is believable, you can’t necessarily assume it’s true
The window could have broken some other way!

10. Induction: Problems (cont’d)
What if the ball in the living-room had gone unnoticed all day?
The second piece of evidence on the list would be untrue (conclusion is therefore unsound)

11. Induction: Problems (cont’d)
Solution: Consider several possible conclusions
Form multiple hypotheses and test each one
Hypothesis: One of those children playing baseball broke the living room window.
Hypothesis: A bird broke the window.

12. Induction: Problems (cont’d)
If the gap between your evidence and conclusion is too great = jumping to a conclusion
Hasty
Not supported by the facts
Essentially a premature inductive leap

13. Induction: Problems (cont’d)
REMEMBER
Hypothesis is just the starting point!
Continue the inductive process as if the question were still to be answered (which it is)

14. Induction: Problems (cont’d)
More evidence = smaller logical gap between evidence and conclusion
Whatever the size of the gap, the crucial step between evidence and conclusion is called an inductive leap

15. Example of bad inductive leap
Messenger: The Joan of Arc Story

16. Conclusion Inductive conclusions ARE NOT facts
Facts = verifiable statements
Inductive conclusions are inferences/opinions
Never 100% certain
At best, highly probable

17. Conclusion – Soundness?
Not always easy to move from evidence you’ve collected to sound conclusion
Gap
REPEAT: More information = smaller inductive leap

18. Analysis of “A Scandal in Bohemia”
The King of Bohemia hires Holmes to get compromising letters and a photograph from a former illicit lover, Irene Adler. As we read the end of this story together, try to figure out what type of reasoning is used by the characters!

19. Analysis of “A Scandal in Bohemia”
Sherlock Holmes is a master of deductive reasoning
Irene Adler, “the woman,” beats Holmes using inductive reasoning
What a great twist!
Rachel McAdams

20. Argumentation HW
Patterns Argumentation Casebook Assignment: Casebook Assignment 
Due 11/22 A Day and 11/23 B Day