The hit point problem

...Or, what do HP actually represent (in traditional RPGs and their descendants)?

Dr Bret Devereaux's recent article on armour and RPGs, in talking about how armour actually works, reminded me about this argument. It's an argument that's older than the internet, an argument that's fundamentally pointless, an argument that's been rehashed thousands if not millions of times... so I thought I might as well get into it briefly.

Let's start here:

Hit points are a combination of actual physical constitution, skill at the avoidance of taking real physical damage, luck and/or magical or divine factors. [...] a near-miss, a slight wound, and a bit of luck used up, [...] more often than not a grazing blow, a mere light wound which would have been fatal (or nearly so) to a lesser mortal. If sufficient numbers of such wounds accrue to the character, however, stamina, skill, and luck will eventually run out, and an attack will strike home

- Gary Gygax, Dragon #24


It seems widely accepted, as well as being straight from the horse's mouth, that hit points are a mixture of a creature's capacity for and resilience against suffering injury ('meat points') and its chances, for various reasons, of avoiding serious injury in situations in which it might suffer serious injury ('grace points').

There's an implication that grace points are mostly 'used up' before meat points. And the obvious interpretation is that there's some (unspecified) ratio of grace to meat.

Unfortunately it's still impossible to arrive at a really self-consistent understanding of hit points in D&D-likes, whether you think HP is 0.1% meat and 99.9% grace, 99.9% meat and 0.1% grace, or anything in between.

HP must be almost entirely meat points, for the following reasons.

• 1 damage to a 100-HP creature has to entail actual physical harm because it can come with 'riders' like injecting poison from a poison-tipped dart. If the dart didn't pierce the flesh 'on hit', it wouldn't have been able to convey the poison. At the other end of the spectrum, 100 damage is enough to kill the creature (or nearly so, depending on edition), so that too must be actual physical harm.
• In trad games, higher Constitution improves HP (i.e., meat points). In comparison, Dexterity, Wisdom, and Intelligence (i.e., grace points) don't improve hit points at all, and neither do weapon/armour use skills and features (when they exist). If grace points made up a non-negligible proportion of hit points, having these attributes would affect HP total.
• Numerous game effects, spells, items, and so on have descriptors that equate even potentially quite small amounts of HP recovery with descriptions of physical wounds closing. I would guess an outright majority of supernatural healing effects involve physical injury in their description, with most of the others being ambivalent or lacking description, and very few indeed talking about restoring anything that seems like grace points.
• Plenty of damage in classic RPGs comes from sources that can't easily be mitigated (or can come from them in principle, for no special rules for when that happens). You character is stabbed while unconscious. Your character falls onto a field of spikes. Your character swims across an acid lake. Your character takes intermittent damage from rotting disease. The moisture is leached from your character's body by a horrid spell. In cases like these, half of the justification for 'grace points' can't be in play: the character isn't 'using skill to avoid harm', the damage isn't 'near-misses', and the character isn't just 'getting tired' or 'pushing their luck'. There are whole character archetypes unlikely to be protected by 'divine forces' or 'magical factors'.

Of course, it's also true that

HP has to be almost entirely grace points, for the following reasons.

• When a 100-HP creature takes 99 damage, this doesn't seem to involve any actual physical harm: in classic games being down to 1 HP has no immediate in-game consequence on the creature (notable exception: D&D 4e's bloodied condition, and even then the effect isn't "a massive reduction in all of the wounded creature's physical capabilities" like you would expect). Per rules, the creature doesn't fall over or involuntarily scream or pass out from pain or anything. (And sure, the game rules are an abstraction, but the same RPGs will have other subsystems that are vastly more fine-grained than the idea that if you put a sword through someone, it has major traumatic effects.) There is never any indication that the GM is expected to improvise these consequences, either.
• Martial characters get more hit points; they're the ones who are best able to avoid harm, because that is what all of their training is for. That harm avoidance is HP.
  
• Characters gain hit points with level, at a rate that is vastly higher than remotely plausible variance in a person's actual ability to survive wounds. You could maybe convince me that some exceptional person could have twice as many 'meat points' as average. Three, four, five times? No way.
• The same plausibility argument applies in general. A twelve-foot giant should weigh about 1500 lbs or 700 kg. If something like that swings an axe at you and it connects, the best you can hope for is that whatever gets lopped off is non-vital. Plenty of D&D-like games would model this attack hitting as something that can be slept off (depending on a damage roll, possibly). High-level characters might take dozens of such hits, depending on the game.

So we've immediately run into contradiction: some things in the game tell us that HP is almost all meat, and other things tell us that HP is almost all grace.

Side note

There's another reason we're unlikely to square the circle and find a self-consistent explanation in (most) HP-based games: Extreme injury.

Suppose 100 damage is just enough to kill some creature: It has 100 HP, or 90, or 90 and then flubs some rolls, or whatever. For this creature, 100 damage kills, so 99 damage is as close to a mortal wound as you can get. This amount of harm heals naturally, and perfectly, very fast, in almost every trad game I've ever seen. In modern editions, this near-mortal wound just goes away overnight! In contrast, I've personally had garden scratches that took a week to heal. Even in OD&D, the upper limit on healing is one month. That would be an optimistic timeframe for being discharged in a modern hospital after "a wound that very nearly killed you". That kind of wound would usually be the beginning of years of physical therapy, if not permanent disability.

COUNTERARGUMENT 1: We can concoct explanations for this, involving abstraction, and how much more survivable wounds are with modern medicine (or with fantasy magic), and how unfun it is to play out deadly infections or characters with degraded abilities, and how we don't want to require a player to play a character who's only definitely going to die rather than dead... sure. I've never heard one that's really comprehensive within the fiction, which is what I'm mostly concerned with.

COUNTERARGUMENT 2: Some games layer lingering injury frameworks, scar systems, etc, onto HP systems. This is fine, and sometimes works pretty well! I will note that in my experience they usually still don't go far enough to make for good simulation, and in particular these additional systems almost always still use a weird sped-up timeframe. I think they're also pretty rare on the whole, for traditional D&D-likes. I like em, though.

COUNTERARGUMENT 3: Some fantasy game worlds might be assumed to have low-level magical healing on tap everywhere, so a very slow trickle of hit points amounts to recovering your HP overnight (or 2d6/night or with one full day of bed rest or whatever). Sure, this works in principle. But I don't think many games come right out and say in their setting information that this is what's going on; it's hard to import into most worlds; it also precludes some genre features, like the existence of lingering injuries and old scars in the broad populace.

Finally, let's flip it around and consider actual practises at the table, where this matters. It's always been the case that certain rules get ignored or changed by swathes of gamers.

At the table, what GM ever describes a sword swing inflicting 10 damage as 'you nearly get hit' or 'they get a little tired jumping out of the way of the sword's arc' or 'fortunately for the ogre, your blade bounces off his belt buckle'? My impression is that this essentially never happens, in part because it makes a hit sound just like a miss, which is both confusing and a letdown.

What I do see, sometimes, is GMs being cautious and sometimes even vague about what is going on within the world – not really a sign that everything is as it should be in the game. They describe damage to enemies as flesh wounds (up until the moment it kills), and damage to characters as minor abrasions and bruises. They're careful not to imply any level of injury that would have actual game world impact (like impeding a creature's movement or making it leave a trail of blood) or later raise questions like 'you said I shattered his arm with that critical hit, how is he climbing the rope now?' or 'you said I was skewered by three arrows, how come I got better completely overnight?'

And likewise, I sometimes see GMs avoid describing the effects of magical healing as 'knitting together wounds', 'restoring all your blood', etc – and sometimes just not describe it at all – because that implies the character had been seriously wounded, and it somehow never feels like a character is badly wounded at the table, no matter how low their HP goes.

And in other cases, I see tables of players and GMs venture into absurdism, where HP loss is always a grisly wound described with relish; such wounds come and go entirely without any knock-on effects within the world, disappearing overnight.

Reconciliation

Is there a way around this without having to hack some extremely core game rules?

Solution 1: Embrace indeterminacy. Hit points don't really mean anything, and wounds are never described until the moment they are gone. If 50 lost hit points are immediately restored by a powerful healing spell then it may well have been a devastating wound (especially if the sufferer was 'dying' as per e.g. 5e rules), and the GM may feel free to describe it that way. But when a character suffers through an afternoon's adventure with 50 missing hit points and they get restored overnight, those ones were in retrospect obviously just a little fatigue (not enough to cause exhaustion), scratches and bruises (not enough to impede movement), and 'expended' luck or divine grace (whatever that means).

Solution 2: Play it straight. This fantasy world is different from our own because of its fantasy elements, and those fantasy elements officially include people's bodies operating utterly differently to how they do in our world. You can go from 'fifty-fifty chance of death' to 'top physical condition' overnight with no magical intervention because that's how it is in this universe. People of this world have no lingering injuries unless they were inflicted by one of the few extremely specific spells or powers that do that.

Solution 3: Beer and pretzels game. Just don't think about it.

Solution 4: It's meta. The game, in being played, produces a story of action in a heroic genre; all the bits of that story which don't make sense are because of (say) unreliable storytellers or other narrative tricks. At the moment it is happening at the table, nothing means anything; after the game, the resulting story is allowed to be inconsistent and impossible, because it's just a story. Yes, this undermines the very concept of roleplaying, so what?

Solution 5: It's stochastic. The lower a character's hit points – whether from injury or being fragile or low level – the more likely they are to die from the next attack. That's the only thing that 'HP' means. All attacks do little to no physical harm until the one that does: health and injury are a random walk on a line. More damaging attacks are both more likely to kill, and more likely to cause successive attacks to kill. And maimings, debilitating wounds, and true life-or-death situations cannot occur (presumably for one of the other four reasons above).

I don't think any of these solutions are very good. #1 is perhaps the most palatable, especially if it starts out hiding behind #3 as so seems more adequate once revealed.

Final thoughts

There's no good way to conclude because when it comes to 'what hit points mean' there's no conclusion to reach, no advice to give – hence the thousands or possibly millions of times something like this has been written or said before. These days I'm personally drawn to the idea of systems designed with something less abstract than hit points, as a way of making play experience more immersive, but, well, I think most players, most of the time, still like HP.