Magic Numbers

I wonder how the societies in a fantasy setting like D&D's would be modified by magic. Would, for instance, magical healing lower the infant mortality rates to modern levels? Since we're generally assuming magic isn't a new thing, would purify food and drink being zeroth level have removed the necessity for alcohol? Civilized peoples, including to an extent in Mesoamerica, have alcohol tolerance because they would all have died of dysentery if they'd had to drink their cities' water. With the town priest able to purify water, the selection pressure for alcohol tolerance might never have arisen (they'd still make booze, of course, but they'd be more prone to alcoholism, as are the Irish, Scandinavians, Native Americans, and Russians, who were not urban enough for alcohol to be a survival mechanism until shortly before modern sanitation was invented).

A part of it depends on how common healing magic is. That article about the real-world breakdown of D&D stats, that I've mentioned before, gives 5% of the population as being "adventurer" material. Assuming an even distribution of ability scores, only 1/6 of those would be capable of casting priest spells (some paladin spells can do the same things, and they're powered by Charisma rather than Wisdom, but the other requirements make all paladins a statistical anomaly). So that gives us one person capable of casting priest spells for every 120 people, and of those, half might choose to be druids. There is, therefore, one priest per 240 people. Now, that all by itself looks like 4.2 healers per person, which is the doctor-patient ratios Italy's healthcare system gets, but remember, those people are mostly 1st-level priests, they can cure wounds and detect poison but they can't remove disease or neutralize poison, they're basically emergency room nurses.

No, to approximate modern medicine you've got to wait till 5th level, which is when clerics can cast remove disease, a 3rd-level spell. And 5th-level characters, as that article says, are Einstein or record-breaking athletes, you pretty much can't assign them a percentage. (The healers can slow poison, using delay poison, at 3rd level, since it's a 2nd-level spell.) Possibly, and in a rather modern touch, the few 5th-level healers (who are, remember, Jonas Salk) might write scrolls with remove disease, which are then distributed to major centers staffed by lesser healers, who cast the spells with a level check (since they aren't capable of casting that spell on their own), thus introducing a chance that treatment fails. Also, those healing centers might well charge 375 gp for the use of the spell, or maybe they'll be charitable and charge only the 30-120 gp that casting a 3rd-level spell would cost. Of course, all of those healers, 1st level and up, can cure wounds, so realistically the only way to die from injury or accident is to do it quickly enough that a cleric can't be brought to bear. (1 in 5 child deaths is from an accident, despite modern medicine, so that would greatly increase their survivability right there.)

Arcane spellcasters would make up twice the percentage of the population that divine do, and there's no druid-cleric split. Basically, 1 person in 60 is an arcane spellcaster, although almost all of those are only 1st-level. But they can do as much damage as a smallish siege-engine with burning hands, and as much as throwing knives (only at 3-4 times the range and 100% accuracy) with magic missile. The few 3rd-level casters can also turn invisible. The very, very few 5th-level ones can demolish entire buildings with fireball and lightning bolt. So realistically, the warfare of this setting is going to be 18th century, not 20th—even if you do have units made up of 1st-level mages, and a few 3rd-level elite agents who can escape unseen after they fulfill their missions, there's not going to be any carpet-bombing, there simply aren't enough mages capable of casting spells that do the right kind of damage. Basically mages would be grenadiers or elite riflemen, and the ballistae, battering rams, and catapults are still going to be the major siege engines. There's no issue of protecting castles against fireballs for the same reason no 19th century military worried about Nikola Tesla coming up and shooting them with lightning bolts, that's about the frequency of 5th-level characters.

So...huh. Looks like all the naysayers, myself included, were wrong. It's entirely plausible to have a setting where magic is real but that doesn't play out too differently from a real-world setting with that level of mundane tech. And actually "like the 'Middle Ages' [i.e. the Renaissance] but with better sanitation and nutrition" is pretty much the setting of most fantasy. They often even involve more alcoholism than real Europe did (because drinking problems are a convenient source of tacked-on drama the characters can angst about).