Identify the fallacy committed in the argument.

All household pets are domestic animals.
No unicorns are domestic animals.
Therefore, some unicorns are not household pets.

Choose the correct answer from the options given below:

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Correct option is A

Fallaci of Illicit Minor

The argument presented is a categorical syllogism. To analyze it, we need to put it into standard form:

• Major Premise: All household pets are domestic animals. (All P are D)
• Minor Premise: No unicorns are domestic animals. (No U are D)
• Conclusion: Therefore, some unicorns are not household pets. (Some U are not P)

Analyzing the Terms

• Major Term (P): Household pets
• Minor Term (U): Unicorns
• Middle Term (D): Domestic animals

Identifying the Fallacy

The fallacy here is the Fallacy of Illicit Minor. Here's why:

1. Undistributed Minor Term: In the conclusion "Some unicorns are not household pets," the term "unicorns" (the minor term) is distributed. This means the conclusion makes a statement about ALL unicorns.

2. Undistributed Minor Term in Premise: However, in the minor premise "No unicorns are domestic animals," the term "unicorns" is NOT distributed. This premise only tells us that unicorns are excluded from the category of domestic animals; it doesn't make a statement about ALL unicorns.

The Rule Violated:

A valid syllogism cannot have a term distributed in the conclusion if it is undistributed in the premises.

Why the Other Options Are Incorrect

• Fallacy of Illicit Major: This occurs when the major term is distributed in the conclusion but not in the major premise. This is not the case here.
• Fallacy of Four Terms: This occurs when the syllogism uses more than three terms, making it impossible to establish a relationship. We have three clear terms.
• Existential Fallacy: This occurs when a syllogism draws a particular conclusion from two universal premises. This is not the primary issue, although it's related because the conclusion is particular (some).