LOGIC OVERVIEW: EXERCISES FOR HOMEWORK

Instructions: Determine whether the following are propositions. If some are not propositions, see if they can be rewritten as propositions.

(1) I think that the Feds are watching me.

(2) Put down the porcupine and come out with your hands up.

(3) I have contacted the spirits of the dead.

Instructions: Identify the premises and conclusions in the following arguments, and identify any premise and conclusion indicators.

(4) In view of the fact that I almost never wash my hair, the odds are pretty slim that I’ll get a date.

(5) I’ll do whatever the guy in front of me wants given that he is holding a gun.

(6) There is an ever-increasing population of flesh-eating zombies; it follows that the apocalypse has begun.

Instructions: Diagram the following arguments. First number each statement, then use plus signs and arrows to connect the numbers in the appropriate argument structure.

(7) My life is over since I lost my cell phone, and my life depends upon that device.

(8) I won’t play follow the leader with you since you have no leadership skills, and, even if you did, you’d just lead me right off a cliff.

Instructions: Identify the informal fallacy in each of the following.

(9) Defenders of capital punishment are wrong since they think that even shoplifters should be executed.

(10) John has diabetes, which he probably got from drinking water since he drinks more water than anyone I’ve ever seen.

(11) The sign said “fine for littering”. Since it was fine, I littered.

Instructions: Put the following in standard propositional form by replacing the clue word with the correct logical connective (for example, “d however e” translates into “d and e”).

(12) x follows from y

(13) a although b

(14) r implies s

Instructions: Which of the following are not well formed propositions?

(15) (P or Q) not (R and S)

(16) if (P and Q)

(17) (P or Q) if and (R then S)

(18) What is the name of the following argument form or fallacy?

if A then B

not B

therefore, not A

(19) What is the name of the following argument form or fallacy?

X or Y

not X

therefore, Y

(20) Make up a modus tollens which leads to the following conclusion: “Therefore, the taxman is not my friend.”

(21) Is the following argument sound or unsound? If unsound, why?

If I am at Graceland then I can see Elvis memorabilia

It is not the case that I am at Graceland

Therefore, it is not the case that I can see Elvis memorabilia

Instructions: What is the inductive strength of the following (that is, very strong, strong, weak, very weak)?

(22) A sixteen-year-old girl was struck by lightning and the next day she won the lottery. Joe was struck by lightning today. Therefore, Joe will probably win the lottery tomorrow.

Instructions: For each of the following, indicate the inductive argument form that is followed, and whether it commits any inductive fallacy.

(23) 21% of Americans believe a UFO crashed at Roswell in 1947. Therefore, there is a 21% chance that Joe believes a UFO crashed at Roswell in 1947.

(24) 4% of 1,247 registered American voters believe that shape-shifting reptilian people control our world by taking on human form and gaining power. Therefore, there is a 4% chance that Joe, who is an American voter, believes that shape-shifting reptilian people control our world by taking on human form and gaining power.