> And then there's a class of problems that neither debugger nor print statements will help: many years ago a very junior co-worker was wondering why his C code was giving the wrong answer for some math. It took me pointing out that one of the numeric types he was using in his code was different from the rest

A debugger and watches on the values of concern absolutely will help with that (so will properly placed print statements), so its a really bad example. (Of course, strong typing helps even more with that particular case.)