Newton's Third Law of Motion.
It reminds me of the technique for recovering from the stall in the Gloster Javelin. With a delta wing and high tail one could get to a situation where the tailplane was blanked off by the mainplane. If a normal recovery didn't work you ejected the navigator. The recoil of the high powered seat would pitch the nose down and normal flight would be recovered.
That was a case where navigators were really useful.