When you discover that your
code is not giving the right results, not because there is any bug in your program, but because there is a bug in the theory on which it is based.
Theoretical bugs are rare but more common than thought. When you find one, your perception of the world improves quantically.
A more day to day example, it is when you realize something you
never saw before, not because it was not there, but because your mental
model of the world didn'
t include it.
case 1
JC: I've been trying to find the bug in this program all night, but its looks perfect. Don't know why sometimes is producing
weird results.
Guru: Its time to chase some Theoretical bugs.
case 2:
Linux_user: The problem with microsoft is not that they produced bad programs, but they copypasted so much software from other
people, that the outcome was a walking Theoretical bug. At some much extent that, when it crashed it means it was really working.