Given the following syllogism:
All unicorns are horses.

This syllogism is:
A) Valid from the Aristotelian standpoint only.
B) Invalid from both the Boolean and the Aristotelian standpoints.
C) Valid from the Boolean standpoint only.
D) Valid from both the Boolean and the Aristotelian standpoints.
E) Conditionally valid from the Aristotelian standpoint.

Question

Given the following syllogism: 
All unicorns are horses.

This syllogism is:
A) Valid from the Aristotelian standpoint only. 
B) Invalid from both the Boolean and the Aristotelian standpoints. 
C) Valid from the Boolean standpoint only. 
D) Valid from both the Boolean and the Aristotelian standpoints. 
E) Conditionally valid from the Aristotelian standpoint.

Quizplus · Accepted Answer

This syllogism is valid from both the Boolean and Aristotelian standpoints. From the Aristotelian standpoint, the syllogism follows the standard form of the universal affirmative, where the major premise (All unicorns are horses) affirms something about every member of a category, and the minor premise (All horses have four legs) affirms something about a specific member of that category. Therefore, the conclusion (All unicorns have four legs) is a necessary consequence of the premises. From the Boolean standpoint, the syllogism conforms to the rules of the Boolean algebra, where the major premise corresponds to the intersection of the sets of unicorns and horses, the minor premise corresponds to the intersection of the sets of horses and four-legged animals, and the conclusion corresponds to the intersection of the sets of unicorns and four-legged animals. Since there is no empty set or contradiction involved, the syllogism is valid.

Given the Following Syllogism