Q: I recently ran into three uses of “principal” where it should have read “principle.” All were in distressingly unexpected contexts: a book on ethics by the philosopher Kwame Anthony Appiah, an opinion by Justice Stephen Breyer, and an article about the resignation of Cathie Black as Schools Chancellor in NYC.
A: A lot of people have trouble keeping these two words straight.
A “principal” is a leading figure (the head of a school, for example) and plays a “principal” (that is, a leading) role. A “principle” is a rule or a standard.
Pat uses a time-honored memory aid in her grammar and usage book Woe Is I: “If you’re good at school, the principal is your p-a-l.”
You’re right that many educated people use “principal” to mean “principle” these days, but this isn’t a recent phenomenon.
The Oxford English Dictionary has published references going as far back as the mid-16th century for the use of “principal” to mean a primary or fundamental point.
The earliest citation is from The Exposicion of Daniel the Prophete (1545), a work of biblical commentary by George Joye:
“Let euery diligent reder knowe hymselfe miche to haue profited, if he but the cheif principalls vnderstand, although it be but meanly.”
The OED notes that the use of “principal” in this sense “is common as a non-standard spelling of principle from the 20th cent. onwards.”
In standard English, though, a “principle” is still a rule. In other words, the fundamental things apply as time goes by.
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