In some things we have come to trust machines more than man; particularly when it comes to complicated calculations. Machines just don't make careless mistakes. Why, though, do we not trust machines, to say pilot a commercial airplane? It's all fly-by-wire anyway. We could just punch in the coordinates, align the satellites and let it rip. We could eliminate the careless error.

Maybe it's because machines don't have a sense of proportion. The complex Excel formula and the life-dependent airplane landing are just as important to a machine -- that is to say, not important at all. You can't point a finger at a CPU and warn it not to "mess this one up" or that "there's a lot riding on these tires."

Somehow, with all of our flaws (in this case read: pilot error) we still prefer having "men in the loop." Until computers can understand the gravity of their responsibilities it will stay this way.