I’m reading an excellent book by David P Clark called Germs, Genes, and Civilization. I like histories and epidemiology, so the two mixed together are right up my alley. It has several interesting aspects, mentions some things that ought to be obvious and yet are not really so self evident, and has a few really fun theories about plagues in Ancient History. Unfortunately it also hits fairly regularly on one of my pet peeves, which is a recurring issue in popular books on plagues and disease. It’s an English language geek one, so probably sounds pretty silly to most people.
The word decimate literally means to kill one out of every ten, from the Latin word decimus, meaning “tenth.” Think decimal system, they have similar roots. Using the word more loosely, but still appropriately, it should be used to refer to the death of a significant proportion of a population, but still in the ballpark of a tenth. Otherwise say, a quarter, a third, a half… a proportion with a hint of precision. The problem is that decimate has become a synonym for destroy, a word used when a very large portion, or a majority, are killed. (This is not to say that one tenth of a population being killed by anything is insignificant…)
One book I took out from the library used decimate in place of destroy approximately every five pages in a chapter on bubonic plague. I couldn’t take it anymore and brought it back to the library unfinished.
The problem is that it still holds its original meaning but is also in the process of that terrifying change whereby if enough people use a word incorrectly it eventually takes on the incorrect meaning. This problem becomes especially confusing when the meanings are a distance apart rather than a matter of nuance.
For example, in one part of the Clark book he was discussing about the decrease in virulence of a specific disease over time. On one page he refers to plague decimating the city, then the next page he points out that a few hundred years later it only killed one tenth of the population. Contrasting a word against its original (true) meaning doesn’t give any meaningful data or even a fair impression of the numbers we’re dealing with here.
Besides, if even super villains can get it right, surely academics can too?