Hawk 37,
sorry my quote ref Airbus 330/340 should not have been so simplistic but I didn't wish to stray too far from the main thread.
Suffice to say that in the most basic FBW Direct Law [stick position= control surface position] the aircraft is stable [download on tailplane]and flyable. This Direct Law is overlaid by artificial means both in Alternate Law and [the usual case] Normal Law. In these cases [in pitch] stick position is usually a G command with Normal Law providing enhanced response and flight envelope protection. This provides enhanced stability to certification requirements. Therefore, CG can be controlled further aft [fuel trim tank transfer] with ensuing lower drag.
This is a short explanation only! please accept that there is more to this...
spleener