Mortal fear shifts us into a neurological state commonly called ‘fight, flight or freeze’. The autonomic nervous system takes over in milliseconds making significant bio-chemical shifts (dumping out cortisol, adrenaline, changing systemic blood flows, etc.) one of which is preferring the hind brain for instant decision making… this mental speed comes at the cost of complexity as it’s largely binary. It’s as intelligent as yes/no or more likely run/fight. This is perfect if the danger is an incoming train or a burning house, but not great for complex social, economic or political decisions.