Chapter 10: DISJUNCTIVE AND HYPOTHETICAL SYLLOGISMS
- Practice -


Multiple Choice:
Click on the button next to the answer you wish to select. Your results will be displayed immediately in the question's text box.

No. of Questions = 30
In these exercises, you will be given hypothetical or disjunctive syllogisms, and asked to determine whether they are Valid or Invalid.

There are two levels of difficulty. In level (a) questions 1-15, then syllogisms will all be in standard form; in level (b) questions 16-30, they may be in standard or nonstandard form.


1 If I win the lottery, then I'll quit my job
If I quit my job, then I'll be unemployed
Therefore, if I win the lottery, then I will be unemployed
a) Valid
b) Invalid
2 John is either a knave or a fool
He is not a fool
Therefore, he is a knave
a) Valid
b) Invalid
3 If the tomato is a fruit, then it contains seeds
The tomato is a fruit
Therefore it contains seeds
a) Valid
b) Invalid
4 If there were no reindeer, Santa Claus would not exist
Santa Claus does exist
Therefore, there are reindeer
a) Valid
b) Invalid
5 If ice were heavier than water, ponds would freeze solid in winter
Ice is not heavier than water
Therefore, ponds do not freeze solid in winter
     
a) Valid
b) Invalid
6 Either wealth is evil or it is good
Wealth is not evil
Therefore, wealth is good
a) Valid
b) Invalid
7 If his clothing carries traces of radioactivity, then he was in the area
His clothing carries no traces of radioactivity
Therefore, he was not in the area
     
a) Valid
b) Invalid
8 If this is not a terrific deal, then my name's not Donald Trump
My name is not Donald Trump
Therefore, this is not a terrific deal
     
a) Valid
b) Invalid
9 If two snowflakes ever formed under identical conditions, they would have the same shape
Two snowflakes never form under identical conditions
Therefore, two snowflakes never have the same shape
     
a) Valid
b) Invalid
10 If astrology had any validity, the predictions of astrologers would be more accurate than sheer guessing
The predictions of astrologers are not more accurate than sheer guessing
Therefore, astrology has no validity
a) Valid
b) Invalid
11 If the fetus is an actual human being, then it has a right to life
The fetus is not an actual human being
Therefore, it does not have a right to life
     
a) Valid
b) Invalid
12 If Melanie is a champion windsurfer, then she must have good balance
Melanie has good balance
Therefore, Melanie is a champion windsurfer
     
a) Valid
b) Invalid
13 If used car dealers were not aware of defects in the cars on their lots, they would not stay in business long
They do stay in business long
Therefore, used car dealers are aware of defects in the cars on their lots
a) Valid
b) Invalid
14 If Israel allows the creation of a Palestinian state on the West Bank, its own survival will be jeopardized
If Israel's survival is jeopardized, violence in the Middle East will increase
Therefore, if Israel allows the creation of a Palestinian state on the West Bank, violence in the Middle East will increase.
a) Valid
b) Invalid
15 He'll leave town if he knows what's good for him
He knows what's good for him
Therefore, he'll leave town
a) Valid
b) Invalid
16 If the island of Thera exploded around 1550 BC, then Crete would have been inundated
Crete was inundated
Therefore, the island of Thera exploded around 1550 BC
     
a) Valid
b) Invalid
17 Whenever Sally finishes a crossword puzzle, she does a little jig
Sally is doing a little jig
Therefore, Sally finished the crossword puzzle
     
a) Valid
b) Invalid
18 If the account of creation in Genesis is literally correct, then the sun was not created until the fourth day
If the sun was not created until the fourth day, then the word "day" cannot be taken literally to mean one cycle of sunrise and sunset
Therefore, if the account of creation in Genesis is literally correct, the word "day" cannot be taken literally to mean one cycle of sunrise and sunset
a) Valid
b) Invalid
19 She will not graduate unless she passes geology
She will pass geology
Therefore, she will graduate
     
a) Valid
b) Invalid
20 A figure is a triangle if and only if its internal angles are equal to two right angles
This is not a triangle
Therefore its internal angles do not equal two right angles
a) Valid
b) Invalid
21 If the human mind were an information processing system like a computer, then creativity would be hard to explain
Creativity is hard to explain
Therefore, the human mind is not an information processing system like a computer
     
a) Valid
b) Invalid
22 The show is over only if the fat lady has sung
The show is over
Therefore, the fat lady has sung
a) Valid
b) Invalid
23 A person cannot love both God and Mammon
Marjorie loves Mammon
Marjorie does not love God
a) Valid
b) Invalid
24 The anti-clot medicine TPA may be sold if and only if it has been approved by the FDA
It has been approved by the FDA
Therefore, it may be sold
a) Valid
b) Invalid
25 Smith would have been convicted only if the jury believed the star witness
Smith was not convicted
Therefore, the jury did not believe the star witness
     
a) Valid
b) Invalid
26 She will get into medical school only if she does very well on the MCAT
She did very well on the MCAT
Therefore, she will get into medical school
     
a) Valid
b) Invalid
27 The President was obligated to notify Congress about sending troops and ships to the Persian Gulf unless considerations of national security prevented him
Considerations of national security did not prevent him
Therefore, the President was obligated to notify Congress about sending troops and ships to the Persian Gulf
a) Valid
b) Invalid
28 If organic molecules can form spontaneously in a liquid containing the chemical building blocks, then life could have emerged in the oceans of the earth without outside intervention
Organic molecules can form spontaneously in a liquid containing the chemical building blocks
Therefore, life could have emerged in the oceans of the earth without outside intervention
a) Valid
b) Invalid
29 Only if a candidate has lots of money will he run successfully for national office
Ronald Reagan ran successfully for national office
Therefore, Ronald Reagan had lots of money
a) Valid
b) Invalid
30 Joe Candidate is running for President either because he has a vision of what's good for the country or because he wants the power and prestige of the office
Joe Candidate is running for President because he wants the power and prestige of the office
Therefore, he is not running for President because he has a vision of what's good for the country
     
a) Valid
b) Invalid



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