I'd argue we evolved to think rationally in order to specifically advance our instinctive drives, rather than the "Triume brain" view of the neocortex and lizar

I'd argue we evolved to think rationally in order to specifically advance our instinctive drives, rather than the "Triume brain" view of the neocortex and lizard brain fighting for dominance. Immediate and extreme danger enforces a realistic and calculating view of reality, when otherwise people tend to avoid thinking about or dealing with a danger. Courage is the ability to choose an alternative besides first choice of fear. But it isn't necessarily rational either, more likely a different instinctive motivation winning out. A completely emotionless person, meanwhile, would probably be completely nonfunctional.