There's a lot more than those three possibilities. I don't really believe that anything is unknowable, aside from semantic arguments about Godel's incompletenes

There's a lot more than those three possibilities. I don't really believe that anything is unknowable, aside from semantic arguments about Godel's incompleteness and things like that. What I'm saying is, that at the moment someone asks you "How long will X take to bring through the software development process", "I don't know" has to be a possible answer or your whole method is corrupt.