An eccentric philosophy professor gave a one question final
exam after an entire semester dealing with a broad array of
topics.

The class was already seated and ready to go when the
professor picked up his chair, plopped it on his desk and
wrote on the board: "Using everything we have learned this
semester, prove that this chair does not exist."

Fingers flew, erasers erased, notebooks were filled in furious
fashion. Some students wrote over 30 pages in one hour
attempting to refute the existence of the chair.

One member of the class however, was up and finished in
less than a minute.

Weeks later when the grades were posted, the rest of the
group wondered how he could have gotten an A when he had
barely written anything at all.

They found his answer consisted of two words: "What chair?"