All tooth fairies are silent visitors. Therefore, no tooth fairies are noisy visitors.
A) Invalid, illicit subalternation.
B) Valid, no fallacy.
C) Invalid, existential fallacy.
D) Invalid, illicit contrary.
E) Invalid, illicit subcontrary.

Question

Quizplus · Accepted Answer

This is a valid statement and there is no fallacy present. It follows the form of a universal affirmative proposition, "All A are B," and the subalternation is valid, "If all A are B, then it follows that some A are B." The conclusion of the subalternation, "no tooth fairies are noisy visitors," is also a universal negative proposition and is therefore valid.

All Tooth Fairies Are Silent Visitors