How to prove that all odd integers > 2 are prime numbers?

[Renato Assunção <assuncao@est.ufmg.br>]

Several scientists were asked to prove that all odd integers higher
than 2 are prime.

 Mathematician: 3 is a prime, 5 is a prime, 7 is a prime, and by
induction - every odd integer higher than 2 is a prime.
Physicist: 3 is a prime, 5 is a prime, 7 is a prime, 9 is an
experimental error, 11 is a prime. Just to be sure, try several
randomly chosen numbers: 17 is a prime, 23 is a prime...
Engineer: 3 is a prime, 5 is a prime, 7 is a prime, 9 is an
approximation to a prime, 11 is a prime,...
Programmer (reading the output on the screen): 3 is a prime, 3 is a
prime, 3 a is prime, 3 is a prime....
Biologist: 3 is a prime, 5 is a prime, 7 is a prime, 9 -- results have
not arrived yet,...
Psychologist: 3 is a prime, 5 is a prime, 7 is a prime, 9 is a prime
but tries to suppress it,...
Chemist (or Dan Quayle): What's a prime?
Politician: "Some numbers are prime.. but the goal is to create a
kinder, gentler society where all numbers are prime... "
Programmer: "Wait a minute, I think I have an algorithm from Knuth on
finding prime numbers... just a little bit longer, I've found the last
bug... no, that's not it... ya know, I think there may be a compiler
bug here - oh, did you want IEEE-998.0334 rounding or not? - was that
in the spec? - hold on, I've almost got it - I was up all night
working on this program, ya know... now if management would just get
me that new workstation that just came out, I'd be done by now...
etc., etc. ..."