A word, please
The other day, someone close to me was wondering about the word “must” — a dangerous activity if ever there was one. “Must” is a verb, clearly. But it doesn’t quite fit in with many other verbs, for example, “walk.” You can say “Today I walk, yesterday I walked, in the past I have walked, and in future I will walk.” But you can’t say “Yesterday I musted, in the past I have musten and tomorrow I shall must again.” This is not a simple matter of action words versus abstract states of being. A verb like “be” works like “walk”: Today I am. Yesterday I was. In the past I have been. In the future I will be. Now, for those who don’t already know the grammatical explanation, ask yourself: When is the last time you misused the word “must”? Have you ever found yourself stuck mid-sentence wondering how to make a past tense out of “I must be tired”? Have you ever worried you used “must” wrong in an e-mail or resume?
Allow me to answer that for you: No. If you’re a native English speaker, chances are you have never suffered a moment’s hesitation or humiliation due to your inability to fully understand “must.” On the contrary, you use the word with grammatical precision every time. You do so without having to think about it. And, now that you have thought about it, you can almost feel your formerly solid grasp of this word dissolving into a puddle of confusion and self-doubt.
That’s why some people hate learning grammar. At times, it’s the equivalent of opening up your car’s hood, ripping out a hose, and saying, “What’s this here thing for, anyways?” But with just a little more attention and guidance, you can understand “must” and its brethren in a way that not only lets your linguistic car keep running, but actually improves its performance.
“Must” is a member of a group called “modal auxiliaries.” Modals are, in turn, a subset of a group many people actually learn about: auxiliary verbs. Most often, auxiliaries are forms of “have” or “be” that, when used with participles, express tense. “I am walking” is different from “I walk.” “I have walked” is different from “I walked.”
The modal auxiliaries “can,” “could,” “may,” “might,” “shall,” “should,” “will,” “would” and our friend “must” add an extra layer of information, the “Oxford English Grammar” explains, while “ought to,” “need” and “used to” qualify as “marginal” modals.
A modal’s job is either “to refer to some kind of human control over the situation, such as permission or obligation” or to “refer to some kind of judgement of the truth value of a proposition, such as its possibility or necessity.” (I would disagree with “Oxford’s” choice of the words “human control,” since we all know that a horse that “can” run fast “may” win the race. But we get the gist.) More specifically, “Oxford” points out that modals express ability, permission, possibility, probability, prediction, volition, certainty and obligation. In other words, they express whether one can, may, will, should or must do something.
Some modals are thought of as having present and past-tense forms: “can” in the past becomes “could,” “shall” becomes “should,” “will” becomes “would” and “may” is sometimes expressed in the past as “might” — even though all those supposed past tenses have unique properties of their own. But, as “Oxford” notes, “The modal ‘must’ and the marginal modals ‘need’ and ‘ought to’ do not have past tense forms and the marginal modal ‘used to’ does not have a present tense form.”
If you’re like most native speakers, you already knew that. But learning the mechanics can helpful and even interesting, even if it’s not a “must.”
— June Casagrande is author of “Mortal Syntax: 101 Language Choices That Will Get You Clobbered by the Grammar Snobs — Even If You’re Right.” She can be reached at JuneTCN@aol.com.