Question Database: Critical Thinking
Asssumptions
The following questions relate to three 'rules of thumb' for identifying assumptions:
Rule #1: The Lonely Premise Rule
An argument with only one premise usually depends on an unstated assumption.
Rule #2: The Rabbit Rule
If the conclusion contains a significant word or phrase that does not appear in any of the premises, then the argument depends on an assumption that makes use of that missing word or phrase.
Rule #3: The Holding Hands Rule
If a premise contains a significant word or phrase that does not appear in the conclusion, then the argument depends on an assumption. The assumption will be a co-premise of the first premise and will make use of the missing word or phrase.
Scientific and technological discoveries have considerable effects on the development of any society. It follows that future predictions concerning societies in which scientific and technological discoveries are frequent are especially unreliable.
Which of the following phrases occurs as a ‘rabbit out of a hat’ in this argument?
I. Future predictions
II. Unreliable
III. Scientific and technological discoveries
IV. Considerable effects
A. I and II
B. I, II and IV
C. I, II, III and IV
D. I, II and III
Answer: A
Topic:
assumptions
Course Level:
First year, critical thinking.
Notes:
1. Scientific and technological discoveries have considerable effects on the development of any society.
A2. ... Future predictions ... unreliable ...
Therefore:
C. Future predictions concerning societies in which scientific and technological discoveries are frequent are especially unreliable.
Which one of the following is the best way to complete assumption A2?
A. Future predictions of scientific and technological discoveries are unreliable.
B. The development of a society requires scientific and technological discoveries.
C. Scientific and technological discoveries have unexpected effects in some societies.
D. Scientific and technological discoveries are an unreliable indicator of social development.
Answer: A
Topic:
assumptions
Course Level:
First year, critical thinking.
Notes:
1. Scientific and technological discoveries have considerable effects on the development of any society.
A2. Future predictions of scientific and technological discoveries are unreliable.
Therefore:
C. Future predictions concerning societies in which scientific and technological discoveries are frequent are especially unreliable.
The ‘holding hands’ rule applies to which one of the following phrases?
A. Considerable effects
B. Future predictions
C. Both A and B
D. Neither A nor B
Answer: A
Topic:
assumptions
Course Level:
First year, critical thinking.
Notes:
The rule says: If a stated premise contains a phrase that does not appear in the conclusion, then an assumption will make use of that phrase.
1. Scientific and technological discoveries have considerable effects on the development of any society.
A2. Future predictions of scientific and technological discoveries are unreliable.
A3. ... considerable effects ...
Therefore:
C. Future predictions concerning societies in which scientific and technological discoveries are frequent are especially unreliable.
The ‘holding hands’ rule applies to which one of the following phrases?
A. Development of any society
B. Especially unreliable
C. Scientific and technological discoveries
D. None of the above
Answer: A
Topic:
assumptions
Course Level:
First year, critical thinking.
Notes:
1. Scientific and technological discoveries have considerable effects on the development of any society.
A2. Future predictions of scientific and technological discoveries are unreliable.
A3. considerable effects .... development of society
Therefore:
C. Future predictions concerning societies in which scientific and technological discoveries are frequent are especially unreliable.
The rabbit rule applies to which one of the following phrases?
A. Concerning societies
B. Development
C. Frequent
D. None of the above
Answer: C
Topic:
assumptions
Course Level:
First year, critical thinking.
Notes:
Final argument:
1. Scientific and technological discoveries have considerable effects on the development of any society.
A2. Future predictions of scientific and technological discoveries are unreliable.
A3. If X has considerable effects on the development of a society and X occurs frequently in that society, then reliable predictions concerning that society require reliable predictions about X.
Therefore:
C. Future predictions concerning societies in which scientific and technological discoveries are frequent are especially unreliable.