This is a "positivity" problem that I often encounter on the internet. Look up "poor health effects on society" and we're met with articles on how economic and political structures sustain poverty, marginalize groups, cause poor conditions and overcrowding ... with a definite slant on "what problems need to be fixed to make this stop happening." A practical definition of what the poor conditions are, or how they are created, or how specific degrees of overcrowding cause specific results, these things are not discussed. The agenda is very definitely not to measure the causes ~ the only people who care about the problem are NGOs with the goal of raising money ... and that takes a positive perspective. We will stop this horrible stuff from happening. Do not look too closely at the horrible stuff.
Now, images and anecdotal evidence can be found in abundance. We're replete with film of poor people picking over garbage piles to find enough useful material to preserve their lives for one more day; but the metrics are lacking. We have no numbers. Numbers do not spawn guilt-inspired donations.
For most game purposes, a scale can be created without having to be expressly concerned with what the scale means. Civilization simply slows a settlement's production when unhealthiness occurs, speeding it up again when general health is improved by cleaning up the land, collecting specific resources or building a market or hospital. This makes sense. A market brings in a wider variety of food, that improves nutrition and the people are more productive.
For my purposes, however, I need to sketch the difference it makes when this town is 1 point less healthy than that town ~ not in a way that affects overall production of the town, which would be useless for a role-playing game, but in a way that will address the players' adventuring.
Most will call out at once that health equals disease ... and that an unhealthy town will be more diseased than a healthy town, meaning that the players should hesitate before drinking the water or eating at the local inn. True enough. But that thought does little more than imply a die roll to see if the water is bad, which is adjusted depending on the town's health. Which, admittedly, is as far as most RPG designing goes.
But it is boring. "Oh, we're not diseased? Then who gives a fuck?"
We want more than the mere chance the players might get sick. We want a feel for the environment, something that encourages dismay when it turns out the place is sour and that encourages relief and happiness when the town is described as cheerfully safe. For that, we need to ask some questions:
Can the players actually tell if a town in unhealthy or not? How so? Would it be the presence of infrastructures that prove a town is healthy (granaries, barays, running water, a market) or would it be the appearance of those infrastructures (crumbling stone, fetid water in the well, filthy streets) that tips the player's hand? How heavy handed should those appearances be? What is the baseline for "filthy" in a dark age, medieval or early renaissance world? On some level, wouldn't everything be, by our standards, unclean?
I'm trying to get the measure of this. Public health is more than just a lack of disease ~ quality of life matters, from a people having to eat rice every day to the amount of solid waste piling up at the end of every alley way. Indulgent behaviour, from drunkedness to sexual vice, has its own public cost ... as well as dangerous delusions shared by a population, such as fear of spirits and the need to burn teenage women as witches.
Mental health is an important factor ~ and a very difficult one to impose on player characters, who for one thing come from a present day where vice and mental illness are encountered daily, in both our ordinary lives and through the media. How much harder is it to explain to a player that their character, having grown up in the woods of Norway, isn't really all that comfortable with the wantonness of 17th century dockside London. On the whole, we can't; we're not anxious to tell the players how to think, and it wouldn't work anyway. They're just not able, with the present mindset, to "get it."
Creating a formula for health that impresses itself upon the player and not the world (which is the hardest lesson that worldbuilders must face, since it is not the world that we actually care about) needs, as ever, some focus that doesn't depend upon the players' ability to conceive or absorb the verbal/visual impression of the town's appearance. Plans for such rules always end in failure, since they ignore the intensive subjectivity of humans ... gawd knows why that's never taken into account. No, no, the world has to be specifically constructed, so that options are clearly dictated at a high or low level of health that are not available elsewhere.
And like with culture, where a high level of culture increases the control on the population, I'm faced with a similar distinction where it comes to health, in the form of "biopower."
I'm familiar with Michel Foucault ... rarely has a mid-20th century academician managed to get quite so far up his own ass, even for a French philosopher. But I find I have to take the life preserver that he throws in this unpleasant sea. From wikipedia:
"...biopower is a technology of power for managing humans in large groups; the distinctive quality of this political technology is that it allows for the control of entire populations. It refers to the control of human bodies through an anatomo-politics of the human body and biopolitics of the population through societal Disciplinary institutions. ... Modern power, according to Foucault's analysis, becomes encoded into social practices as well as human behavior as the human subject gradually acquiesces to subtle regulations and expectations of the social order. It is an integral feature and essential to the workings of—and makes possible—the emergence of the modern nation state, capitalism, etc. Biopower is literally having power over bodies ..."
Effectively, the condition that is arrives with the health-saving grace of running water is the universal expection that everyone will wash their hands and their bodies. The condition that arrives with the market is that the quality of goods will be regulated and controlled ... and it is this social policy, and not just the presence of the improvement or technology, that imposes the improved health of the community. As culture demands a certain attitude from the player, health demands a certain level of grooming and social responsibility ... and where that social responsibility is evidently lacking in the population, at the point where the players can be as filthy as they like without anyone particularly caring, it is time to worry.
I shall, obviously, continue to think about this. But I find it odd that each step forward seems to employ a consistent motif that when things get better, it is necessarily freedom that suffers.