I've always felt that one of the scariest phrases in the English language is, "it seemed like a good idea at the time."

For a storyteller, one of the key ways to use illness and healing is to put your players in a situation where healing has gone wrong. Magic is inherently unpredictable and game concepts like wild magic open up countless storytelling opportunities, but non-magical healing is at least as unpredictable and probably much more so. The tricky thing about medicine, and about science in general, is it takes a very long time to know if what you're doing is a good idea or not. Case in point: leeches. Leeches were a mainstay of Western medicine for an embarrassingly long time. Healers would apply the leeches when they suspected it would be the optimal therapy but weren't positive -- a practice which we today think of as "empiric therapy," or treating based on our best guess -- and then they would observe the results. A certain percentage of the people who were treated with leeches did get better, and from this observation, generations of healers believed that leeches cured illnesses. The belief that leeches work persisted until  enough people began to question whether their observations were really in accord with reality. Nobody was using statistical analysis back then, but as observation skills improved and the scientific method of thought caught on, people began to notice that while some people did improve with leeches, approximately the same (and often more) number of people also improved without them. This process would be akin to what we today think of as a randomized control trial: get a thousand people with the same illness, randomly treat half of them with leeches and half of them with something else, and see which group does better. We can get some good, reliable knowledge when we look at large groups of people in a systematic way, but we can get ourselves pretty badly misled when we look at very small groups, especially if we have a bias for what result we hope is true.

There's another related reason why a treatment can catch on a bit too fast: because it's new and exciting. You'll sometimes hear scientists talk about the importance of Malcolm's Law or Malcolm's Rule, which I consider to be one of the cornerstones of ethical science. Malcolm's Rule is named for Ian Malcolm, the mathematician from Michael Crichton's Jurassic Park. In the film version -- and I'm embarrassed to admit I don't actually know if the line is spoken the same in the novel, which I've never read -- Malcolm speaks the wonderful and compelling line, "your scientists were so preoccupied with whether or not they could that they didn't stop to think if they should." In essence, Malcolm's Rule reminds us that having the capacity to use a new technology doesn't mean that it's a good idea. I could easily give a couple of examples from modern science, but let's look at a fascinating historical example: the use of x-rays to treat infections. X-rays first began to be widely studied around the end of the nineteenth century by men such as Röntgen, Edison, and Tesla (although Röntgen wouldn't go on to earn the same degree of fame as Edison and Tesla, he did bring home a Nobel Prize for the work). Röntgen discovered that he had machines which could produce rays that passed through solid objects, and when he took a picture of his wife's hands, he discovered that this could allow people to see bones inside the body. By the early twentieth century, x-rays were a widely-used medical tool, even as evidence of the dangers of radiation mounted (Marie Curie had won her own first Nobel Prize by this time, but hadn't yet fallen ill). In the early 1920's, someone got the idea that radiation could be used to kill small creatures without killing large ones -- which is true, as far as it goes -- and so a Jewish public health organization set up a campaign to expose tens of thousands of children to high-dose x-rays as a means of eradicating ringworm infections, which would make it possible for the children to immigrate to the United States and escape the rising tide of fascism. Over the course of nearly twenty years, almost thirty thousand Eastern European children were systematically irradiated. The good news is that, as a treatment for ringworm, x-ray exposure was fantastically effective; the radiation therapy proved to be among the best treatments ever devised, and even today, many of our modern antifungal drugs aren't as effective. The bad news, as we today might guess but the people of the time couldn't have known, is that radiation has long-term side effects. By adulthood, many of the treated individuals would go on to develop cancers, anemias and other blood disorders, and other sequelae with much worse consequences than ringworm. As Malcolm's Rule predicts, given an exciting tool to use, well-meaning people who were ignorant of the consequences caused a great deal of trouble. Then again, pick your evil: die of cancer at 50, or die in a Nazi concentration camp at 20? Since most of us aren't precognitive, we have to pick our path and hope for the best. Ian Malcolm would no doubt have had something to say about that, too.

For a storyteller, the possibilities are endless. Send a group of adventurers on a quest to find a cure for a horrible illness in the first half of the campaign, and make them deal with the unforeseen consequences of their cure for the second half. Set the characters up against a lawful good cleric about to unleash a horror on the land out of the best of intentions. Obviously, this doesn't apply solely to stories of plague and healing, either; pretty well any scenario can very easily turn into a "there was an old lady who swallowed a fly" situation with just a little bit of direction from a canny storyteller, and then it's just a question of letting the characters choose the consequences they're most willing to live with.

Four years ago, Dr. Eris Lis, M.D., began writing a series of brilliant and informative posts on RPGs through the eyes of a medical professional, and this is the one that appeared here on July 6, 2013. Lis is a physician, gamer, and author of the Skirmisher Publishing LLC OGL sourcebook Insults & Injuries, which is also available for the Pathfinder RPG system.