Delving into a word’s etymology can be enlightening, disillusioning, and even fun. But sometimes, word histories can be misused for prescriptive purposes. The etymological fallacy is the argument that a word’s “true” or “best” current meaning should be the same as its original meaning or the meaning derived from its various etymological parts.
Such arguments can be compelling. To the average reader — or even to the average writer facing a confident, strong-willed editor — appeals to etymology for meaning can seem like reasonable explanations. But we copyeditors should know better.
The word decimate is a common focus in discussions of the etymological fallacy, and with good reason. Yes, it comes from a practice of the Roman army of quelling dissent among the ranks by executing 10 percent of a group of unruly or mutinous soldiers. And Oliver Cromwell even gave the word a new life in the mid-seventeenth century with his decimation tax on Royalists, a tax of — you guessed it — 10 percent. So there is certainly a historical precedent for decimate referring to some sort of reduction by exactly 10 percent. But how we use the word has changed.
Today, decimate most commonly means “greatly reduced or destroyed.” Some language purists/snoots (we’ll call them 10-percenters) still insist that it can only mean “reduced by 10 percent,” obviously, they argue, because deci- comes from the Latin root decem, meaning “ten” — the percentage is built right into the word!
It’s a common belief, and there’s a common counterargument — or at least counterexample — for it, but it isn’t a good one: If you believe that decimate can only mean a reduction of 10 percent “because etymology,” then you must also believe that December is the tenth month of the year for the same reason. Reductio ad absurdum!
Here’s why this isn’t a good argument: When December was first named, it was the tenth month of the year in the ancient ten-month Roman calendar; likewise September, October, and November were, respectively, the seventh, eighth, and ninth months. According to the OED, two more months were added to the calendar year in 713 B.C., and even then they were added to the end of the year, so December was still the tenth month. The beginning of the year wasn’t moved to January until 153 B.C.
So we ended up with a calendar in which the name of the twelfth month means “tenth month” not because the word changed meaning, but because the calendar changed. This is why it’s a bad argument: It was a metric shift, not a semantic one. Decimate, on the other hand, underwent a semantic shift.
But not to worry; there are still plenty of examples to illustrate how absurd the etymological fallacy can get. If etymology determined meaning, then
- Homophobia could only mean “self-hate.”
- Only buildings made of stone could be dilapidated.
- Girl could refer to a child of any gender.
- All vaccines would contain cow pox.
- There should be a lot more drinking at symposia.*
A list like this is great for illustrating why the etymological fallacy is, well, a fallacy, but it might not be enough for the 10-percenters. After all, we have plenty of other words whose current meanings are roughly equal to their original ones. Can’t decimate be one of these?
Here’s another tack: If the 10-percenters were correct, then decimate would simply be a shortcut to a mathematical equation, with all the nuance and connotation of asymptote or cosine. If one student in a classroom of ten missed class because of a bad cold, it would be reasonable to say that the class was decimated by a virus. Because one student missed class.
That’s just not how people use the word, and that’s not how readers understand the word.
This points the way toward what, from an editorial point of view, is probably the best counter to many etymological fallacies. Part of the copyeditor’s job is helping readers understand what writers are trying to say, so a more important question than “what does this word really mean?” is “what will readers understand when they read this word?” Readers can be wrong, of course, so there is room here for an abstract “reasonable reader” to be your guide, and there may be some gray areas.
But with decimate, the route is pretty clear: A reasonable reader will understand it to mean a great reduction or great destruction, with all the negative connotations that come with it. They won’t, however, pop open a calculator app to figure out exactly what the writer means, and they shouldn’t have to.
* You can believe this statement to be true regardless of the etymology of symposium.