There is an important difference between "all hp represent physical toughness (ie meat)" and "all hp loss (ie damage) is physical injury". The first entails the second. But the second doesn't entail the first.
I think 3E, by its official rules, asserts the second but denies the first. It has rules features, though, that encourage the first (ie hp = meat) interpretation (I mention 4 of them below).
I think that 4e, by its offical rules, rejects both proposition. This opens up the door for martial healing, fear attacks causing psychic damage, etc.
I think that AD&D is ambiguous as between the 3E and 4e approaches, but it certainly has some features that (in practice) push in the hp = meat direction.
There's no way to muddle through IMO (past the first few levels) with damage being purely physical.
By 11th level, an average hp Barbarian (3e) with 18 Con has 111 hp. An improbably lucky barbarian who rolls max hp and has a 20 Con will have 187 hp.
By comparison, a megaraptor (huge sized dinosaur) has only an average of 76 hp, while the typical tyrannosaurus only has 171 hp. How exactly can you muddle through justifying that an average 11th level barbarian can absorb more physical punishment than a megaraptor
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The barbarian isn't a magical class. All of his powers are extraordinary, not supernatural. So then how is it that he achieves this seemingly superhuman feat of resilience? I posit that he doesn't. He may take some small amount of physical harm when he is hit, but he doesn't get bitten in half by the t-rex and then pull himself back together through sheer fortitude.
I agree with this as a problem for the "hp as meat" approach. But you can hold that "all hp loss is physical damage" without holding that "hp are meat" - for example, by taking the "damage divisor" approach instead. (You could also go DougMcCrae's way, and say that high level PCs become magical or quasi-magical meat - the barbarian's hp become an EX ability, a bit like a troll's regeneration - less than mundane in some fashion, although not being lost in an anti-magic field.)
I'm not certain what you mean by a damage divisor, but since you're responding to my comment on hp representing purely physical damage, I'll assume you mean "hp as only physical damage."
By "damage divisor" approach I mean the idea that all hp loss represents physical damage, but that the
amount of physical damage that X lost hit point represent is proporionate to level.
On this approach, when a 2nd level PC add a second die of hp, it's functionally equivalent to keepig hp static, but dividing all damage by 2. And, in general, when an Nth level PC has N hit dice, that is the functional equivalent of dividing all damage taken by N.
I think this is a very common interpretation of the standard rules text on hp, especially this from the d20 SRD:
Hit points mean two things in the game world: the ability to take physical punishment and keep going, and the ability to turn a serious blow into a less serious one.
One natural reading of that sentence, in light of the way that hp work, is that all hit point loss represents physical damage, but a given amount of hit point loss means more or less damage depending on the total number of hp that the PC in question possesses. (That passage, for example, seems to rule out purely mental or emotional effects - like fear or 2nd ed-style Psychic Crush - causing hp loss. It also seems to rule out your swashbuckler narration - the swashbuckler is not making more serious blows less serious, but avoiding them altogether.)
The main places where the "divisor" approach breaks down are these:
*classic healing magic - if 32 hp on my 8th level fighter represents the same amount of injury as 4 hp on my 1st level fighter, how come Cure Light Wounds can fully heal the injury of the second character, but barely help the (ostensibly identical) injury of the first character?
*falling damage - how does fighting skill let you turn a fall into something less serious? are all high level PCs thief-acrobats?
*AoE damage - when you're caught in the middle of a fireball or dragon's breath, how can your fighting skill make that less serious? (Not everyone has a shield to duck behind, and not all these effects are directional.)
*the killing blow.
The last of these is interesting. Think about an actual "divisor rule" with standard D&D rounding down: an 8th level PC would take no damage from an attack dealing fewer than 8 hp. So no matter how badly injured, a blow would have to be at least an 8 hp blow (the best possible sword attack from an ordinary person with a longsword) to drop the PC. A 7 hp blow would do nothing.
Whereas with the actual hp mechanics that we have, the 7 hp blow can drop the 8th level PC to 1 hp, and then the merest scratch of a dagger can drop him/her. I don't know what those who hold with the "all hit points are physical, but there is a divisor effect" approach make of this fact, that when we get to very low hp left blows that should be having no effect can in fact drop the character. It's as if, at very low hp totals, the divisor is suddenly lost - the character loses his/her combat skill.
That's why I say that, on the divisor approach, you have to squint a bit to make it work. (On the pure "hp as meat" approach, in which we ignore the second phrase in the SRD definition, we don't get any of these squinting issues. Damage hacks away meat, while healng spells pack it back on. But of coures we do get the much more blatant issue of high level fighters being meatier than dinosaurs.)
I don't think the two are contradictory at all.
I think when the 1st ed says both that hp loss is not all physical damage (in the famous/notorious essay) and also glosses loss of hit points as physical damage (in the footnote to the psionic combat table) it has fallen into contradiction.
I don't think it's an especially severe contradiction. My only point was that even the 1st ed DMG had trouble making up its mind what hp loss represents.
