This is an excerpt from a 1967 speech in the U.S. House of Representatives by
Representative Adam Clayton Powell:
He who is without sin should cast the first stone. There is no one here who
does not have a skeleton in his closet. I know, and I know them by name.
Powell's argument can be expressed as follows:
No sinner is one who should cast the first stone.
All people here are sinners.
Therefore, no person here is one who should cast the first stone.
Use an Euler diagram to determine whether the argument is valid or invalid.