Without getting too philosophical about _why_ things fail (yes I'm cheating), I reckon there are only two practical generic things you can do: 1. Make it very

Without getting too philosophical about _why_ things fail (yes I'm cheating), I reckon there are only two practical generic things you can do: 1. Make it very small (how small is subjective and language dependent of course). 2. Make the large part fault tolerant and recoverable, e.g triple redundancy. (or make the lower level part fault tolerant). Leaving a third option of making perfect software in the face of immense complexity sounds more like magic to me, I doubt any solution in this area could be generalised.