By Richard E. McDorman
Modal verbs have expressive power far beyond what their simple forms would suggest. I have encountered very view linguistic works that conceptualize the English verb system in a way that gives modality the full respect it deserves (most ESL course texts that I have read mainly emphasize tense and aspect), yet it can be argued that modality is the most robust of all grammatical categories related to the English verb. After all, English makes more distinctions in modality than in any other grammatical category explicitly marked on or expressed by the verb.
Consider that English really only has two verb tenses (past and non-past, when tense is construed as a grammatical category expressed by morphological changes to the verb itself), even though grammatical dogma insists that it has three or twelve (English does not really have a future “tense” in the way that Spanish, French and many other languages do, although English does have multiple ways of expressing future time, which is itself a clue to the true formally futureless character of the English tense system).
Depending on how one analyzes the aspectual system, English has at most three aspects (simple, progressive and perfective) and in its highest registers, three moods (indicative, imperative and subjunctive, although the imperative is only expressed distinctively in the verb to be and the subjunctive only in the verb to be and the third person singular of all other verbs and then only in the present tense). Including the grammatical categories marked on the verb itself (person and number, which are only hanging on by a thread, or should I say by an –s), the English verb system makes no more than a tripartite distinction in any grammatical category other than modality.
It is thus in the modality that we find the full efflorescence of verbal meaning in English. While tense limits us to I come, I came and (when construed liberally) I will come, and aspect extends our reach just a bit farther to I come, I’m coming, I’ve come, and I’ve been coming, modality allows English speakers to break free of our binary shackles of time and escape the monochrome desert of have’s and been’s and –ing’s to run free in the vibrant fields of can and may and must and will, each with its own unique and beautiful shade of meaning. And just when we’ve managed to regain our breath, we turn the corner to be awed by an even richer palette filled with could and should, would and might, and the slightly exotic ought to, had better and even once in a while, dare and shall. So, with such a great diversity of meaning and semantic richness, it is no wonder that English language learners struggle with these, the crown jewels of the English verb system.
Yet despite their great expressive power, modal verbs are often avoided by English language learners. Although they seem to love will and manage to use can, it seems as if there is nothing we can do to wrest a single might or couldn’t from their mouths. I believe that it is the great complexity of meaning carried by modals that makes them so difficult for learners to master, despite their very modest form. Yes, to be sure, beginners tend to make formal mistakes like adding the unnecessary third person singular –s (as in *Yes, he cans instead of Yes, he can) or tossing in the unwanted to (as in *He can to go instead of He can go), and negating them often drives our poor students to tears (*I don’t can go instead I can’t go: as a tonic for this malady, I remind my students that do can never come before modals, only after, and that don’t is the bane of all modal verbs—the two can never exist side-by-side). But it is using modals correctly (essentially, selecting the right one and knowing when to use one in the first place) that poses the greatest challenges for English language learners. Even the most advanced learners have great difficulty with the all-important modal + have + past participle construction (as in He must/may/might/should have gone), yet without acquiring this powerful structure, they will never reach their full expressive potential in English.
In addition to their semantic complexity, the fact that many languages completely lack modal verbs makes them even more difficult for learners to acquire (it is generally difficult for L2 speakers to acquire grammatical strategies that are completely absent in their L1), but we should not let this discomfort due to lack of familiarity hold our students back. I believe that we must teach modal verbs with as much gusto as we can muster. I am of the persuasion that we should teach them one at a time and not all at once, presenting the most common modals first. Once students have integrated can and will into their lexicon, we can then move ahead with may and must, and eventually for intermediate and advanced students focus on the “past” forms would, could, should and might. The less common shall, ought to and had better should be reserved for the most advanced students who have already mastered the more frequent and useful modals. I also believe that students should be sensitized to the frequency of modal verbs in English so that they can appreciate just how important they are (I think this can help alleviate modal verb aversion, at least in part). Listening and reading activities that function as “modal verb scavenger hunts” in which students identify and then talk about how a certain modal verb is used in different ways can be an engaging and effective tool for helping students learn more about modals (for example, count the number of times could appears and then identify the different ways it is used in the first chapter of Alice’s Adventures in Wonderland; a free and legal open-source copy is available at http://www.gutenberg.org/files/11/11-h/11-h.htm).