When people speak of a fear being rational, I think that what they really mean is “fear which has a rational basis”, and not that the experience of fear itself is reasoned. But people make many lazy omissions in speech with the guess that others will know close enough what they mean.
That’s more or less the distinction I was trying to make in my earlier post. If you can already reason it through, then feeling afraid also won’t help, although it can happen anyway. Just like how pain is a necessary message to prevent further injury, but once you’ve gotten the message it’s nice to not need the incapacitating effects.
