I’m usually at a loss to know what to write on an all-purpose blog, but the true anecdote below seems appropriate and too good not to preserve somehow.

A friend was complaining to me today about the two exams he had to write with finals approaching.  I said to him that I will often save time with what I call the “Putnam question,” named after my teacher, Hilary Putnam.

You may have heard the supposititious story about the philosophy professor who gave the one word exam, “Why?”  (And then stories differ over whether it was “Because” or “Why not?” or some other short answer that got full credit.)   Well, Putnam was eccentric, but not that eccentric.  He gave the same exam in every one of his courses, consisting of just a single question:

Compose a question suitable for an exam in this course, and answer it.

Naturally students would write complicated, multi-component questions–before going on to write equally complex answers–but in any case effectively writing the exam for the professor and taking away that onerous job.  Since then, as I said, I have often used the Putnam Question myself, at least for the essay portion of an exam.  The genius of it is that one gets to grade the student on the difficulty of the question, the excellence of the answer, and the match between the two.

But as a student I wanted to save labor as much then as I do now as a professor.  And so one year (in Putnam’s course on “Scientific Knowledge”) I determined to answer Putnam’s question by simply writing it twice:

Compose a question suitable for an exam in this course, and answer it.

Compose a question suitable for an exam in this course, and answer it.

The first instance obviously counted as a suitable question, because it was Putnam’s own, and the second was obviously an answer, just as the first was an answer to Putnam’s own.  Putnam gave me a straight A.  And that was easy, right?

Yet, quite unlike itself, it was an answer never to be repeated.  After that year Putnam always took care when announcing the final to add the explicit condition: “But you won’t get credit if you answer the exam recursively!”