re: Debugging is twice as hard as writing the code in the first place.

Yeah - still not a fan of this quote. It relies on 'writing the code in the first place' meaning something of any importance. I could say that my 12 line strong AI program is written and just needs to be debugged a little... given these terms.

Sounds more like an entropy argument where incorrect code is much more highly probable than correct code, and while our caffeine and cool ranch dorito fueled minds may get into the neighborhood of order it only comes at great cost: every bug we move out of code, ends up munching in the dorito bag we left under the table several weeks before.

It seems the fundamental point, or a way to better define 'writing code' is to say that you can write code that works for some input/outputs much more easily than for ALL input/outputs. Therefore, Skilling et al can create a house of cards that works for some time but once reality random walks to something unanticipated then someone is left shuffling out the door.