4. Suppose your friend Allen gives the following speech. Is Allen right? Has he presented a valid argument? Should we accept his conclusion? "I can prove that I know logic! Michael Jackson was a famous logician, so it follows that either Michael Jackson was a famous logician or Allen knows logic. Right? But since Michael Jackson was not a famous logician, and we just proved that either Michael Jackson was a famous logician or Allen knows logic is true, we can conclude that Allen knows logic. See? Flawless logic!"