Like any computer, it has no "reason" for doing something - it doesn't "know" why it is doing something because the design is "hard-wired", but we are not.
If I may nitpick a little - while the process is indeed hard-wired, the output could be considered as a process of "reason[ing]" and "know[ledge]". Where you're absolutely correct is that the results of said process are only as good as the data being fed into it, as well as the fact that the artificial reasoning process is by its very nature circumscribed in terms of what it can handle. This is why modern autoflight systems are designed so that they will not only disengage if those parameters are exceeded, but will also not permit re-engagement until those parameters are returned to within those limits.
The human brain is infinitely better at recognising and coping with such abnormal situations, and that fact underpins the notion that electronic aids like the FD should never be trusted blindly - if it looks wrong, it probably is.
Airbus recognizes this by stating that if you don't intend to follow the FDs, turn them both off.
As do Boeing, and probably most if not all of the others.
Originally Posted by
petitb
I think a big problem lies in the (apparent) Airbus philosophy which seems to advertise it's aeroplanes as ultra safe and if the automation is used throughout, the aeroplane "will fly itself" and you are protected throughout the flight regime.
That's a common misconception. Airbus's FMC/autoflight setup is no more complicated or clever than anyone else's. Envelope protection is a feature of both Airbus and Boeing's FBW systems (albeit implemented differently), and with apologies for sounding like a broken record, do not confuse FBW with automation!
The industry-wide push for adoption of automation originated with the airlines, not with Airbus, or for that matter, any other manufacturer. PJ2 wrote a wonderfully concise post a while back on the encroachment of the MBA generation on airline management, and now as then I concur completely with his assessment.