Grammar sticks a foot out and trips all of us sometimes. But after you shake your fist at it in well-founded outrage and pick yourself up, check out Word-Wise Wednesdays, a series of grammar tips for dealing with some of the most commonly confused grammar rules. Once a month we’ll offer a new tip to help demystify the rules that give us the most trouble. As ever, we welcome questions and discussion.
Insure and Ensure Are Not Interchangeable.
At a Glance
Use “ensure” not “insure” unless there’s a policy, deductible, claim, exclusion, or the like involved. Mnemonic: alphabetically, “e” comes before “i”—use “e” first.
Ensure = to make certain.
This is a broad verb that applies to many activities.
Insure = to reserve money against an uncertain future loss.
This is a narrow verb that applies almost exclusively to a contractual obligation.
If in doubt, ensure is probably the word you want. However, another way to think about it is that ensure is positive, proactive, and has a ring of certainty. I always hear the first syllable as a wide-open gesture—we envision, encircle, enlarge, ensure. In contrast, insure is worried, guarded, and has a ring of anxiety about it. I hear its first syllable as closed and confined—innermost, inadmissible, insecure, insure:
We ensure campus buy-in through collaboration and communication.
We insure the campus against earthquake and dragon attack.
Note how easily the preposition “against” follows insure. Ensure, in contrast, leads so confidently toward what follows, it often takes a “that” or no preposition at all:
Well-designed publications ensure that the right students apply.
Appropriate web governance ensures timely updates.
Can you ensure on-time delivery?
If you replace the verb in the last example, you change the meaning, requesting not assurance but an agreement beforehand that failure will result in compensation. The conversation might go like this:
“Can you insure on-time delivery?”
“Why, yes one can. If they don’t receive the books by the date specified, we will refund your shipping fees. The insurance costs an additional 59 cents for the first hundred dollars of fees.”
Tricky! The trickiest cases are where there is no formal insurance policy, but some informal compensation is in play:
I will ensure that the whole team attends by betting each one a week’s wages that the whole team won’t attend.
I will insure that the whole team attends by betting each one a week’s wages that the whole team won’t attend.
Each of these verbs could be correct, yet they have different meanings, evident in the kinds of sentences that naturally follow. The first emphasizes the role of the speaker (I will ensure), suggesting a following sentence that continues to be about the speaker. The second (insure) emphasizes the compensation consequence and would suggest a subsequent sentence about the wager:
I will ensure that the whole team attends by betting each one a week’s wages that the whole team won’t attend. See, I know how to motivate for short-term results.
I will insure that the whole team attends by betting each one a week’s wages that the whole team won’t attend. It’s a steep price, but it’s worth it.
The narrow specificity of insure leads more naturally to further discussion of the predicate (the verb and subsequent elements). You can swap the second sentences between the paragraphs, but there’s a subtle jar as you switch focus.
To choose between these verbs in such a tricky case, ask yourself if the emphasis should fall on the doer or the consequence. Choose ensure to emphasize the confidence of the doer, and choose insure to emphasize the consequence after the action.
Do we have any assurance of your good intentions? Assure is similar to ensure, yet in the present tense usually indicates a communication meant to allay anxiety:
I assure you, the whole team will be there.
I will ensure that the whole team attends, even if I have to drag each one into the meeting.
Note that, used transitively in the usual way, assure always takes a direct object that is a person or group of people (you, in the foregoing example). Consider these assurances:
She reassured the crowd that peace talks would resume in the morning.
He assured his boss that they would meet the deadline.
I looked it up in the dictionary to assure myself I had it right.
Explicit web governance standards also assure the administration that everyone understands their obligations.
Assure is most comfortable in the interpersonal space, where both the subject and the object are people; the impersonal subject of the last example creates some static as we try to find the people connected to assure. Although correct, it is only appropriate in very narrow circumstances. That seems pretty simple, right?
Not Sure and Simple. Unfortunately, assure isn’t always usual. It can be used in a technical sense as a synonym for insure. In fact, some insurance companies have the word assurance in their names. It can even be used as a synonym for ensure:
I assured compliance by making sure the agreement was on the record.
Yes, yes, maybe that’s a kind of insurance. What a mess!
And, to make a full confession, some authorities suggest that these three verbs are all interchangeable. (Tears hair silently.)
Yep, that’s language for you. Ensure, insure, and assure—the squabbling descendants of a single Latin verb, all trying to claim their spot in your sentence. I’d like to assure you that these rules are irrefutable, but in that case we’d be working with computer code. The social code—language—is a dynamic, chaotic system. Not utterly chaotic, mind you, but a chaotic system. Language rules help us dance in unison for a measure or two. The more we all follow them, the more understanding we generate—until we don’t.
Asserting differences among these verbs allows us greater precision and specificity:
Please ensure that your tray tables are stowed; we’re not insured against the damage they might cause in the event of a rough landing. (I’ll walk through one more time to assure myself that everything is shipshape.)
 Simply speaking, a transitive verb takes a direct object. If that definition just adds one opaque grammar term on top of another, then I like to focus on the word “transit” inside transitive. A transitive verb carries its action forward until it runs into an object. An intransitive verb just moves. Confusingly enough, the same word can be transitive or intransitive. “I run every day” vs. “I run the light board at the community theatre.” However, if you get the difference between those two sentences, you now understand transitive.