How promiscuous are the French?

Some time last summer the paper published without comment the following fact. Asked at the end of his (active) life with how many Frenchwomen he has slept, the average answer of the Frenchman is 14; ask the Frenchwoman with how many Frenchmen she has slept, and her average is 7.

Let M be the number of Frenchmen that have lived, say since 1500 and let F be the number of Frenchwomen that have lived since the same moment. Let P be the number of pairs in that whole population that have slept together. The average number of Frenchwomen a Frenchman has slept with equals P/M, and similarly the average number of Frenchmen a Frenchwoman has slept with is P/F. With P/M = 14 and P/F = 7, the unavoidable but somewhat startling conclusion would be F = 2M, i.e. in the French population twice as many females as males! [The most likely explanations are general dishonesty or between the sexes a different definition of "having slept with", but that is neither here nor there.]

I would not have written this note, had it not been for the reaction of one of my friends. As an example (probably of people not understanding what they talk or write about) I had quoted my paper in one of my letters to him. But, somehow, my friend had no problems at all with the quoted statistics! He saw no discrepancy.

It is amazing, but probably an example of what studying Law, and then leading a Life in Business, can do to an otherwise subtle and intelligent mind.

And for us scientists, it should be a reminder, each time we don't understand the world we live in.

Austin, 11 October 1993

prof. dr. Edsger W. Dijkstra
Department of Computer Sciences
The University of Texas at Austin
Austin, TX 78712–1188

transcribed by Tristram Brelstaff
revised Sun, 30 Dec 2007