# PHI103: Informal Logic

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1) In the truth table for an invalid argument,
Student Answer: on at least one row, where the premises are all true, the conclusion is true.
CORRECT on at least one row, where the premises are all true, the conclusion is false.
on all the rows where the premises are all true, the conclusion is true.
on most of the rows, where the premises are all true, the conclusion is true.
Instructor Explanation: The answer can be found in Chapter Six of An Introduction to Logic.
2. Question : The truth table for a valid deductive argument will show
Student Answer: CORRECT wherever the premises are true, the conclusion is true.
that the premises are false.
INCORRECT that some premises are true, some premises false.
wherever the premises are true, the conclusion is false.
Instructor Explanation: The answer can be found in Chapter Six of An Introduction to Logic.
3. Question : Truth tables can be used to examine
CORRECT deductive arguments.
abductive arguments.
All of the above
Instructor Explanation: The answer can be found in Chapter Six of An Introduction to Logic.
4. Question : A conditional sentence with a false antecedent is always
false.
Cannot be determined.
not a sentence.
Instructor Explanation: The answer can be found in Chapter Six of An Introduction to Logic.
5. Question : Truth tables can determine which of the following?
Student Answer: CORRECT If an argument is valid
If an argument is sound
If a sentence is valid
All of the above
6. Question : "P v Q" is best interpreted as
Student Answer: P or Q but not both P and Q
CORRECT P or Q or both P and Q
Not both P or Q
P if and only if Q
7. Question : What is the truth value of the sentence "P v ~ P"?
INCORRECT False
Cannot be determined
Not a sentence
8. Question : One of the disadvantages of using truth tables is
Student Answer: INCORRECT it is difficult to keep the lines straight
T's are easy to confuse with F's.
CORRECT they grow exponentially and become too large for complex arguments.
they cannot distinguish strong inductive arguments from weak inductive arguments.
9. Question : "Julie and Kurt got married and had a baby" is best symbolized as
CORRECT M & B
M ¡æ B
M ¡ê B
10. Question : If P is false, and Q is false, the truth-value of "P ¡êQ" is
CORRECT true.
Cannot be determined.
All of the above.

• PHI103: Informal Logic -

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