Cpt 104,
to correct what I assume was a slip (hmm, or a skid, to open a whole new can of definitional worms
), modern fighter aircraft are designed to be
statically unstable which is then compensated for by the FBW computers.
Plenty of aircraft are slightly dynamically unstable. Take your hands off and they go into the infamous 'graveyard spiral'... it is quite easy to compensate though, as a pilot. Statical unstability really requires the pilot to be on his toes at all times and correct any attitude deviations. Can be done though, the Wrights did it.
Cheers,
/Fred