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Hypothetical Syllogism Quiz #3

Robert Harris
Version Date: June 14, 2000

Choose the correct answer in each case.

1. If the planning committee approves the door design, John will install it today. But the planning committee rejected the design, so John will not install the door today.

a. affirming the consequent
b. denying a conjunct
c. denying the antecedent
d. affirming a disjunct
e. valid

2. Weíve narrowed the problem in the walkway light to two possibilities: either the transformer is defective or the bulb is not working. Iíve just checked the bulb and it works okay. So the transformer must be defective.

a. affirming the consequent
b. denying a conjunct
c. denying the antecedent
d. affirming a disjunct
e. valid

3. Because of the limits of the circuit, we cannot run both the microwave oven and the toaster at the same time. But the microwave is not running, so the toaster must be on.

a. affirming the consequent
b. denying a conjunct
c. denying the antecedent
d. affirming a disjunct
e. valid

4. The refrigerator will not drip if the freezer compartment was defrosted last week. Look, the refrigerator is not dripping. So we know that the freezer compartment was defrosted last week.

a. affirming the consequent
b. denying a conjunct
c. denying the antecedent
d. affirming a disjunct
e. valid

5. There are only two possibilities for this flat: your valve stem is leaking or there is a nail in the tire. I just noticed that your valve stem is leaking, so that means you donít have a nail in the tire.

a. affirming the consequent
b. denying a conjunct
c. denying the antecedent
d. affirming a disjunct
e. valid

6. If Jane is planning a trip to the mountains, she will be packing the picnic basket. Look, she's packing the picnic basket now. That proves she's planning a trip to the mountains.

a. affirming the consequent
b. denying a conjunct
c. denying the antecedent
d. affirming a disjunct
e. valid

7. We've narrowed the problem in our pretzel making to two final possibilities: either we mistakenly used self-rising flour or the oven was too hot. But I've just checked the oven temperature and it is just right. Therefore, we must have used self rising flour by mistake.

a. affirming the consequent
b. denying a conjunct
c. denying the antecedent
d. affirming a disjunct
e. valid

8. John cannot both draw the fish for biology and photograph the trees for art at the same time. I know he is not drawing the fish because he finished it yesterday, so he must therefore be photographing the trees now.

a. affirming the consequent
b. denying a conjunct
c. denying the antecedent
d. affirming a disjunct
e. valid

9. Flight 456 will be late if the jet stream shifts down from Oregon into California. Here's the weather report: the jet stream has shifted down into California. Well, that means that Flight 456 will be late.

a. affirming the consequent
b. denying a conjunct
c. denying the antecedent
d. affirming a disjunct
e. valid

10. A CD player will contain an eight-times oversampling circuit if the CD player is high quality. This Sony CD player contains an eight-times oversampling circuit, so this Sony CD player must be high quality.

a. affirming the consequent
b. denying a conjunct
c. denying the antecedent
d. affirming a disjunct
e. valid


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About the author:
Robert Harris is a writer and educator with more than 25 years of teaching experience at the college and university level. RHarris at virtualsalt.com