(debilitating) fear of heights = fear of pain
the type of fear of heights that is so bad that you become completely paralyzed and incapable of even moving can't be overcome until you first overcome your fear of pain.
Suppose that A fears pain and B doesnt fear pain
it isn't that A & B feel the same thing and one fears it and the other doesnt.
A & B feel completely different sensations
A feels scary pain and B feels nonscary pain
the difference is not one of intensity.
they are two fundamentally different sensations.
scary pain is completely debilitating.
if I am far enough above the ground then I am completely paralyzed with fear
furthermore fear of pain seems to be unique to humans.
Apes obviously aren't afraid of heights.