Reductio ad absurdum...
The FAR subsection dealing with static longitudinal stability was written, I guess, to ensure increasing control forces at high angles of attack so as to be a natural aerodynamic anti-stall characteristic of the airplane.
So Boeing claims that MCAS isn't an anti-stall system because it was developed to counter unsuitable control forces, That I grant you, qualifies as reductio...
Two questions then:
1.does MCAS trigger with a certain alpha value only, or anytime the aircraft has sensed stall ID?
(Stall ID is a Boeing term for how the aircraft determines when its stalled...its determined by either alpha vane or low airspeed)
2. Is the failure of a stall prevention feature defined as a critical failure? Ie, a failure too consequential for Boeing's cobbled together MCAS?
Another bit of Latin: After both accidents Boeing was claiming the fallacy of post hoc, ergo propter hoc. Turns out it wasn't false.