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

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

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?

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.”

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 2015 Homecoming.

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”

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

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.

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.