Originally Posted by
AlexGG
derjodel, probably the reason for shear pins is that the probability of mechanical failure somewhere in the system is higher (or is considered higher) than the probability of pilots having a duel on control sticks.
More likely, I think, the reason is that the shear pins (or whatever) can (or may, with some probability) effectively mitigate a failure elsewhere.
There is no mechanical/automated system that can cope with the two pilots fighting each other on the controls. Either the pilot who is correct disables (or persuades to desist) the other one, in time to recover, or the ground will intervene and end it.
Two of anything is only for redundancy if one bails out (figuratively or literally), in case of disagreement
two is the worst number to have - voting is inevitable tie. Three physical pilots isn't really going to fit in today's aircraft, but in the future we may be able to have a third synthetic pilot, whose job will be: in the event of disagreement, determine which is the errant pilot and remove them from the control path. Pilots or AOA vanes, take your pick - two is not enough to resolve a disagreement.