It is false that some four-sided triangles are commonplace figures. Therefore, some four-sided triangles are not commonplace figures.
A) Valid, no fallacy.
B) Invalid, existential fallacy.
C) Invalid, illicit subcontrary.
D) Invalid, illicit contrary.
E) Invalid, illicit subalternation.

Question

Quizplus · Accepted Answer

The statement commits an existential fallacy because it assumes the existence of "four-sided triangles," which is a contradictory or impossible concept. Therefore, the argument's conclusion cannot logically follow.

It Is False That Some Four-Sided Triangles Are Commonplace Figures