When my last post ended, we had established that there was a baseline in D&D that 14 to 20 points of damage is enough to kill a man, with 4 to 8 generally being enough to ‘drop’ him and cause him to start dying. This is based off of die type and Constitution score and (importantly) assumes a Level 1 character. That most people are Level 1 is one of my guiding principles, and I believe it will serve us well here.
Let’s take our notional baseline and put a finer point on it: the statistically average Level 1 Commoner (human, for what it’s worth). His hit die type is a d6 and he has a 10 CON, so his (statistically average) hit points are 3 (rounding down) — he will begin dying after just a few points of damage and will be dead after a maximum of 13 damage. A Warrior will, on average, have 5 hp and die after a total of 15 damage, making them a bit more resilient but still in the same ball park. PC classes are comparable. Extra points in CON effectively add 1.5 points to the total damage a character can take before death, so a tough Warrior might be able to survive up to 18 points of damage, but he’s still down after 6.
So far we can make sense of this. Hit points represent the body’s ability to sustain damage. After so much punishment, you will begin dying and, eventually, you body will beyond the point where it can recover; you are dead. If you’ve been hurt and survived, rest and medical attention can, over time, return you to health. Hit Points only measure the proximity to death; they do not track scars, broken bones, pulled tendons, torn muscles, etc. except in as far as those things bring a character closer to death. Hit Points on their own can not tell you if you lose a limb, or an eye, or threw out your back. Hit Points (on their own) can’t track bruises, fatigue, hunger, or exposure to the elements. they just tell you how close you are to dying in a coarse-grained kind of way. But for that, they do a pretty good job: some people are tougher than others, but everyone is effectively within a few points of each other (with the exception of extreme Constitution), and everyone heals at the same rate.
The real problem comes from scaling hit points with level and, perhaps to a greater extent, random hit points.
Scaling Hit Points
The way D&D does hit points is that you get X hit dice of type Y, where X is the level of your character. So a Level 1 Commoner (on average) has 3hp, but once he hits level 2 he jumps up to 7 hp! It’s worth noting here, though, that this isn’t really twice the vitality; he has 7hp, but he’s still dead at -10, so instead of dying after 13 damage he’s dead after 17. It’s not a huge leap in those terms, but it does mean that he can take a lot more punishment before he ‘drops.’ What’s more, the average Level 2 Commoner can take more punishment than the average Level 1 Warrior, both before he drops and before he’s dead. That is to say Level matters, which I think is appropriate. The difference between Level 1 and Level 2 in many respects is more important than the difference between Warrior and Commoner; the Level 2 character is better than the Level 1 character fundamentally (though a Level 2 Commoner who says that to a Level 1 Warrior is unlikely to ever see Level 3).
Does this mean that the Level 2 character has more meat to them? That their bones are stronger, that they’re more resistant to decapitation? The answer is no: hit points don’t track those sorts of things, and if they’re important hit points are the wrong tool to use. All it means is that the Level 2 character can keep fighting despite more severe punishment and that he can recover from graver wounds. After 13 damage the Level 1 Commoner’s body can’t keep up and shuffles off this mortal coil; the Level 2 Commoner has taken the same punishment but is still holding on, and may yet recover. The Level 2 character is more resilient.
At Level 3 the Commoner would have 10 hp and survive up to 20 damage before dying, and it starts to become clear that such a character can keep fighting despite having taken wounds that would drop a lesser man. In fact, when the Level 3 Commoner has taken enough damage to drop, the Level 1 Commoner is on death’s door and fading fast. The Level 3 character is truly heroic, though still within ‘normal’ bounds. By the time he reach Level 5, though, he has 17 hit points and can sustain 27 points of damage before his last gasp; he fights on after receiving a wound that would kill other men outright. He is on the verge of the superhuman.
Random Hit Points
But what if he’s not? This assumes that a character could increase in level without significantly increasing their resilience, but I don’t think that’s much of an assumption at all. First, it’s easy to imagine a Wizard who becomes a better Wizard without becoming noticeably tougher. Second, it’s already coded into the way we do hit points: statistically unlikely though it may be, that Level 5 Commoner could have only 7 hp (if he rolled ones for every Level after the first). And in terms of the purpose of the Hit Point system I think this flaw may be the worst because it does damage to the purpose of hit points: it divorces them from the character they’re meant to represent.
I think I get why we do it. Dice are a thing that gamers love, they’re fair, and they help us determine otherwise uncertain things. But my contention is that hit points are, in one sense, not uncertain. The character either is or is not getting more resilient, and either by a lot or a little. In a way, it’s as important as whether he’s a Wizard or a Warrior, a Gnome or a Half-Orc, Lawful or Chaotic. It talks about his ability to act beyond his old limits; it is deliberate. Determining this randomly causes problems because now anyone can suddenly be twice as resilient without a firm connection to the fiction; it’s random.
There’s not really a good ‘fix’ for this, and in many cases I’m not sure a fix is desired, but I think it’s important to recognize. If you don’t acknowledge that your character’s hit point increase is tied to the fiction then the mechanic is going to become divorced from the character’s reality.