Is the number one a prime number?
I occasionally get some cruel and bitter criticism from an odd source. I’m putting my response here for two reasons:
(1) so that I can simply refer them to it and not have to repeat myself or engage in the equally impersonal displeasure of internet arguments, and
(2) I think there is something interesting to be learned about mathematics, logic, and knowledge more generally.
It all started when I wrote a very controversial book about an extremely taboo topic: mathematics. In my book ABCs of Mathematics, “P is for Prime.” The short, child-friendly description I gave for this was:
A prime number is only divisible by one and itself.
I thought I did a pretty good job of reducing the concept and syllables down to a level palatable to a young reader. Oh, boy, was I wrong. Enter the angriest group of people I have met on the internet.
You see, by the given definition, I had to include one as a prime number since, as we should all agree, it is divisible only by one and itself.
Big mistake.
