1. Propositions and Truth Tables
Chapter 1, Unit B
Propositions and Truth Tables

2. Essential Question:
From the previous section, we know common fallacies to avoid when making arguments. Now, what constitutes a logical argument?

3. Key Term: PROPOSITION A claim that may be either true or false
Must be a complete sentence
Examples:
My brother lied to my parents.
I did not brush my teeth this morning.
Five more minutes.
When are you going to the store?

4. Key term: NEGATION Opposite of a proposition
Makes the opposite claim of the proposition
Examples:
My brother did not lie to my parents.
I did brush my teeth this morning.
Double negation: “not not” p
“No, I didn’t cheat on my significant other.”

5. Key Term: CONJUNCTION “and”
“p and q are true” mean that BOTH p and q are true
True example: Mr. Halfmann is the PCHS principal and Ms. Limoz is the senior class advisor.
False example: Mr. Miyashiro is the PCHS principal and PCHS plays Radford for the Homecoming.

6. Key Term: DISJUNCTION “or” in logic class means the inclusive “or”
Inclusive “or” either or both are true
Example: Students who took Algebra II or MOW 2 can be in college math
Exclusive “or” one or the other, but not both
Example: You can be dead or alive
“or” in logic class means the inclusive “or”

7. Key Term: “IF…. THEN..”
Statement that proposes something to be true on the condition that something else is true
p = hypothesis, q= conclusion
Structure of the sentence: If p, then q
Example: If a daily assignment is listed on the calendar, then I have to do it for homework

8. Practice Rephrasing Conditionals:
You will pass your exam if you study tonight.
Being an Asian student implies that the person is good at math.
It rains whenever I don’t have my umbrella
A drought will lead to high fruit prices.

9. Answers to Rephrasing Conditionals:
If you study tonight, then you will pass your exam.
If you are Asian, then you are good at math.
If I don’t have my umbrella, then it will rain.
If there is a drought, then the fruit prices are high.