Suppose, in the above situation, the man had instead answered: ‘Brothers and sisters have I none, but this man’s son is my father’s son.’ Now whose picture is the man looking at?

We will start with some good old-time puzzles which have amused many a generation. Some of these, many of you already know, but even for those in the know, I have a few new wrinkles.

This puzzle was extremely popular during my childhood, but today it seems less widely known. The remarkable thing about this problem [...]

A fellow graduate student of mine at the University of Chicago had two brothers, aged six and eight. I was a frequent visitor to their house and often did tricks for the children. One day I came and said,’ I have a trick in which I could turn you both into lions.’ To my surprise, [...]

A related incident occurred many years later when I was a graduate student at the University of Chicago. I decided to have a job as a seller. I applied to a vacuum cleaner company and had to take an aptitude test. One of the questions was, ‘Do you object to telling a little lie every [...]