it’s fairly simple:
clinical death = heart stops = reversible, depends on circumstances
brain death = irreversible = perma-dead. no one’s ever come back.
legal death = brain dead (not clinical) or court order (missing for X years/etc)
I’m putting the current medical definition aside, we’ve been pushing the boundaries of what’s possible and who knows what the next centuries redefine. For the longest time in human history “clinical death” was almost always followed by permadeath.
As the person doing the dying you can’t rationalize it as “no worries, it’s just clinical, I’ll be back”. You die, it’s light out, later on, a blink for you, you recover and are told “you were clinically dead”. You experienced death for all intents and purposes because I don’t think there’s a cognitive process that allows you to differentiate the stages. Heck, deep sleep might be how death “feels” like.
Do people fear death (excluding suffering) because of the threshold itself or the FOMO? Missing on what would come next?
The medical standard for death has equated it with brain death since at least 1981, though arguably it started in the 1960s. The history of the definition of death[1] is fascinating.
1. https://pmc.ncbi.nlm.nih.gov/articles/PMC5570697/