1. Chapter 3: Reality Assumptions
This chapter will cover
Reality assumptions
Patterns of deductive reasoning
Using deductive reasoning to test logic, discover truth, make decisions, avoid stereotyping, and understand argument.
Why is it useful to learn the patterns of deductive reasoning? Pg. 86

2. Reality Assumptions
Beliefs about what is true and factual about the world.
Based on unique experience of individual
Discuss the notion of assumptions- often hidden and though sometimes directly stated by the speaker, they are usually implied. Also call factual or descriptive assumptions

3. Detecting Reality Assumptions
Toulmin’s Model
Issue: Should we use the SAT or ACT scores to predict success in college?
When considering an issue, what are the reality assumptions?

4. Toulmin’s Model
Claim - Students should not apply to colleges at which SAT scores are 200 points higher than theirs.
Warrant
(Reality Assumption)
Scores are accurate predictions of how well a student is prepared
Reason
Students will not likely succeed
Based on
Value-Education is valued but how education is measured varies according to different assumptions

5. Test only predicts level of struggle for first year.
Toulmin’s Model
Claim
Colleges should not use standardized test scores as a measure of success.
Reason
Test only predicts level of struggle for first year.
Warrant
(Reality Assumption)
Students success based on character qualities that are not measured by the tests.
Based on
What is the reality assumption?

6. Toulmin’s Model
Issue: Should trials and executions be televised

7. Toulmin’s Model Claim: Trials and executions should be televised
Warrant
(Reality Assumption)
Televising trials would inform the public about our judicial system.
Reason:
Public has the right to have more information about the courts and the judicial system.
Based on
What is the reality assumption? What is the value assumption? Which has priority?
Warrant
(Value Assumption)
Freedom of information is an important value

8. Reasoning Deductive Reasoning General statement to a specific instance
Deductive reasoning aims to give us certainty about what is true in a given situation. Certainty is established when the premises (reasons) are true and stated in correct form.

9. Reasoning Deductive Inductive Aims for Certainty General to Specific
Gives us Probabilities
Specific to General
Chapter 6

10. Deductive Reasoning Syllogism- a classic example
All men are mortal. (major premise)
Socrates is a man. (minor premise)
Therefore, Socrates is mortal. (conclusion)
Defining a syllogism

11. Deductive Reasoning Validity
Correct form makes an argument valid (logical).
Accurate content makes it true.
When the form is valid and the content is true, the argument is sound.

12. Deductive Reasoning is content true? All students eat pizza.
Claire is a student at CSU.
Is form valid?
Therefore, Claire eats pizza.
Is it sound? No

13. Deductive Reasoning is content true? All women are terrible drivers.
Jane is a woman.
Is form valid?
Therefore, Jane is a terrible driver.
Is it sound? Yes

14. Deductive Reasoning Pattern of Deductive reasoning
All As are Bs Categorical statement
m is A.
Therefore, m is B

15. Deductive Reasoning Categorical Statement All As are Bs. A B
A statement in which
members of one
class are said
to be included in
Another class.
Example

16. Conditional/hypothetical syllogism
Modus ponens:
‘the way of affirmation’: the antecedent leads to the consequent.
If A, then B
A Therefore, B B A
A is the antecedent; B is the consequent.

17. Conditional/hypothetical syllogism
Modus tollens:
‘denying the consequent.’
If A, then B
Not A
Therefore not B B A
If I have strep throat, then the culture will be positive.
But the culture is not positive.
So, I don’t have strep throat.

18. Deductive Reasoning Questionable Premises
All drivers who speed are subject to a fine.
You are speeding.
Which premise can be contested?
Therefore, you are subject to a fine.

19. Deductive Reasoning Enthymeme
Key part is implied rather than directly stated.

20. Deductive Reasoning Sound Argument: Correct Form True Premises
False
Sound Argument:
Correct Form
True Premises
Unsound Argument:
Correct Form
Untrue Premises
Valid
Unsound Argument: Incorrect Form, True Premises
Unsound Argument: Incorrect Form, Untrue Premises
Invalid

21. Deductive Reasoning Deductive reasoning can:
Uncover Reality Assumptions
Discover Truth and Make Decisions
Combat Prejudice and Stereotyping

22. Skill
A critical thinker uses reasoning to discover truth and prevent stereotyping

23. Chapter 3: Reality Assumptions
Checkup
Reality versus value assumptions
Validity in an argument
What makes a deductive argument sound
What does deductive reasoning aim to establish