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Whether to ensure a distinction between "ensure" and "insure"

When it comes to "insure" and "ensure," do you find it necessary to keep them distinct from one another?

For some people, this may not be much of an issue, since "ensure" and "insure" sound so similar. But things get trickier when it comes to writing. 

English Professor Anne Curzan says she runs into this question of distinction all the time when she's editing other people's work.

"I try to make sure that I'm doing it correctly, because I think I know the rule on [ensure and insure], but maybe I'm not right," Curzan says.

The rule that Curzan learned is that "ensure" is to guarantee something, while "insure" is used in the sense of insurance policies. That is, when you "insure" your car, your provider will "ensure" that you receive information about your policy.

This rule does seem to correlate with what you'll find in many style guides, including the Associated Press Stylebook and the New York Times Manual of Style

"Ensure" comes into English from Old French in the 1500s. Its meaning is similar to the one we know today -- to make someone sure, to convince someone.

When "insure" comes in, it appears to be simply a variant of "ensure." Over time, we create the distinction between the "e" and the "i," so that "insure" refers only to matters of insurance, while "ensure" is used for everything else.

That's pretty straightforward, but not everyone agrees with this distinction. Ina video on The New Yorker's website, "Comma Queen" Mary Norris explains the magazine's unique preference for "insure":

“’Insure’ and ‘ensure’ are almost synonyms, although ‘ensure,’ meaning ‘guarantee,’ is more literary, or at least seems more British. Some people (and publications) limit the use of 'insure' to the job that Philip Roth’s father did. Why does The New Yorker use 'insure' for both senses? Maybe because it’s never wrong.”

Lexicographer Bryan Garner called this"one more idiosyncratic thing" about The New Yorker's style sheet. What do you think? Do you feel there should be a distinction between "ensure" and "insure," or do you stand with The New Yorker on this one?


Anne Curzan is the Geneva Smitherman Collegiate Professor of English and an Arthur F. Thurnau Professor at the University of Michigan. She also holds faculty appointments in the Department of Linguistics and the School of Education.
Rebecca Kruth is the host of All Things Considered at Michigan Public. She also co-hosts Michigan Public's weekly language podcast That’s What They Say with English professor Anne Curzan.
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