Modals and auxiliary verbs in English
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Modals
Auxiliary do
Auxiliary have
Be (auxiliary and main verb)
Summary
Notes
Modals
Historically, the modals of English, which are listed in (1), derive from a special class of
verbs in Germanic (the ancestor of English and the other Germanic languages).
(1)
can, could, may, might, must, shall, should, will, would
Modals have always differed from ordinary verbs in Germanic, and in the course of the
history of English, they have diverged from verbs even further, to the point where they
now belong to a syntactic category of their own. Because many modals have meanings
that are often expressed in other languages by verbal inflections, this syntactic category is
called I(nflection).
In what follows, we review the ways that modals differ from verbs in English, both
morphologically (what forms they exhibit) and syntactically (how they combine in
sentences).
Range of forms
Modals and verbs differ in the range of forms that they exhibit. English verbs appear in a
number of distinct forms (see Verb forms and finiteness), whereas modals have a single,
invariant form. Modals never end in -s, even in sentences with third person singular
subjects.
(2) a. * She { can-s, may-s } play the piano.
b. She { can, may } play the piano.
Modals also lack productive past tense forms. It is true that could, might, should, and
would originated in Germanic as past tense forms of can, may, shall, and will. But today,
only could can serve as the past tense of can, and that only in certain contexts.1
Example
Potential paraphrase
(3) a. Nowadays, you can get one for a
dollar.
b. Back then, you could get one for a
nickel.
(4) a. We can go there tomorrow.
b. We could go there tomorrow.
(5) a. You may ask the boss.
b. You might ask the boss.
(6) a. Shall I pick up some bread?
b. Should I pick up some bread?
= ... it is possible to get one ...
= ... it was possible to get one ...
= It is possible for us to go there ...
=/= It was possible for us to go there ...
= You are allowed to ask the boss.
=/= You were allowed to ask the boss.
= Is it a good idea for me to pick up some
bread?
=/= Was it a good idea for me to pick up
some bread?
Finally, modals lack present and past participles; the missing forms must be paraphrased.
(7) a. * { Cann-ing, may-ing } play the piano pleases her greatly.
b. { Being able, being allowed } to play the piano pleases her greatly.
(8) a. * She has { cann-ed, may-ed } play the piano.
b. She has { been able, been allowed } to play the piano.
Nonfinite contexts
A further difference between modals and verbs is that modals, unlike verbs, can't occur in
nonfinite contexts (for instance, in to infinitive clauses or after another modals). Once
again, the missing forms must be paraphrased.
(9) a. In to infinitive
clause,
b.
c.
(10) a. After (another)
modal,
modal
paraphrase of
modal
verb
modal
* She
wants
She
wants
She
wants
* She must
to can speak Spanish.
to be able to speak
Spanish.
to speak Spanish.
can speak Spanish.
b.
c.
paraphrase of
modal
verb
She must be able to speak Spanish.
She must speak Spanish.
Do support contexts
The inability of modals to appear in nonfinite contexts gives rise to three further
differences between verbs and modals, all of them manifestations of an important
phenomenon in the grammar of English called do support.
Emphasis. In the simplest case, do support affects affirmative sentences containing a
finite verb whose truth is being emphasized. It involves replacing the finite verb by the
verb's bare form and adding a form of auxiliary do to the sentence in the appropriate
tense (either present or past tense). This form of do then receives emphatic stress, as
indicated by underlining in (11).
(11) a. Unemphatic (without do support) He dances; she sang.
b. Emphatic (with do support)
He does dance; she did sing.
By contrast, emphasizing the truth of a sentence that contains a modal is achieved by
simply stressing the modal. Do support with modals is ungrammatical.
(12) a. Emphasis without do support He can dance; she will sing.
b. Emphasis with do support
* He does can dance; she does will sing.
Negation. Do support with verbs occurs not only in emphatic contexts, but in two further
syntactic contexts: negation and question formation. In both of these cases, the form of do
that is added to the affirmative or declarative sentence doesn't necessarily receive
emphatic stress (although it can).
In English, sentences containing modals are negated by simply adding not (or its
contracted form n't) after the modal. Do support is ungrammatical.
(13) a. Negation without do
support
b. Negation with do support
He { may, must, should, will, would } not dance.
* He does not { may, must, should, will, would }
dance.
Sentences without modals, on the other hand, require do support in English. As in the
case of emphasis, the verb appears in its bare form, and an appropriately tensed form of
the auxiliary verb do is added to the sentence, followed by negation.
(14) a. Negation with do support
He { does, did } not dance.
b. Negation without do support * He not { dances, danced }.
He { dances, danced } not.
Question formation. The final difference between modals and verbs concerns question
formation. If a declarative sentence contains a modal, the corresponding question is
formed by inverting the modal with the subject. Do support is ungrammatical.
(15) a. Question without do
support
b. Question with do support
{ Can, may, must, should, will, would } he dance?
* Does he { can, may, must, should, will, would }
dance?
Again, however, in a sentence without a modal, question formation requires do support.
That is, it is an appropriately tensed form of do, rather than the verb itself, that inverts
with the subject.
(16) a. Question with do support
{ Does, Did } he dance?
b. Question without do support * { Dances, Danced } he?
Auxiliary do
This section summarizes the properties of auxiliary do, introduced in the previous section
in connection with do support. Auxiliary do belongs to the same syntactic category as the
modals---namely, I(nflection), because it shares their properties with one exception (in
contrast to modals, it has an -s form).
The goal of the previous section was to establish the special status of modals, and we
used the facts of do support as a criterion for distinguishing modals from verbs. In this
section, we consider some of the same facts, but with a different focus. Rather than
focusing on the distinctive properties of modals, we focus on the morphological and
syntactic properties of auxiliary do itself.
Like all English auxiliaries (the others are be and have), auxiliary do is homonymous
with an ordinary verb - in this case, main verb do. The examples that follow explicitly
contrast main verb do with auxiliary do.
Range of forms
As just mentioned, the only difference between auxiliary do and the modals is that it has
an -s form. In this respect, it patterns with ordinary verbs, including its main verb
counterpart.
(17) a. Modal
I can dance the polka.
b.
He { can, * can-s } dance the polka.
(18) a. Auxiliary do I do dance the polka; I do not dance the polka; do you dance the
polka?
He do-es dance the polka; he do-es not dance the polka; do-es he
dance the polka?
I do the dishes.
b.
(19) a. Main verb
do
b.
(20) a. Other verb
b.
He do-es the dishes.
I dance the polka.
He dance-s the polka.
Nonfinite contexts
In all other respects, auxiliary do behaves like a modal rather than like an ordinary verb.
For instance, it is ungrammatical as a to infinitive, after modals, or as a gerund. Notice
the clear contrast between the judgments for auxiliary do in (22) and main verb do in
(23).
(21) a. Modal,
b.
c.
(22) a. Auxiliary
do,
b.
c.
(23) a. Main verb
do,
b.
c.
(24) a. Other verb,
b.
c.
in to infinitive * They want to can dance the polka.
after (another) * They will can dance the polka.
modal
gerund
* Their canning dance the polka while blindfolded
is unusual.
in to infinitive * They claim to do dance the polka.
Intended meaning: They claim that they do dance
the polka.
after modal
* They will do dance the polka.
Intended meaning: It will be the case they do
dance the polka.
gerund
* Their doing dance the polka while blindfolded
was unwise.
Intended meaning: That they did dance the polka
while blindfolded was unwise.
in to infinitive
They want to do the dishes.
after modal
gerund
in to infinitive
after modal
gerund
They will do the dishes.
Their doing the dishes was considerate.
They want to dance the polka.
They will dance the polka.
Their dancing the polka while blindfolded is
unwise.
Do support contexts
Auxiliary do also behaves like a modal in do support contexts. Double instances of
auxiliary do are ruled out, just like double modals are (see (10a)). Once again, auxiliary
do and main verb do differ sharply, as shown in (26) and (27).
(25) a. Modal,
b.
c.
(26) a. Auxiliary
do,
after emphatic
do
negative
question
after emphatic
do
b.
negative
c.
question
(27) a. Main verb
do,
b.
c.
(28) a. Other verb,
b.
c.
after emphatic
do
negative
question
after emphatic
do
negative
question
* He does can dance the polka.
* He doesn't can dance the polka.
* Does he can dance the polka?
* He does do dance the polka.
Intended meaning: It is the case that he does dance
the polka.
* He doesn't do dance the polka.
Intended meaning: It isn't the case that he does
dance the polka.
* Doesn't he do dance the polka?
Intended meaning: Isn't it the case that he does
dance the polka?
He does do the dishes.
He doesn't do the dishes.
Does he do the dishes?
He does dance the polka.
He doesn't dance the polka.
Does he dance the polka?
Auxiliary have
Let's now turn to auxiliary have, which combines with past participles (-en forms) to
form the perfect forms of verbs. Auxiliary have behaves like a V with respect to its
morphology and its occurrence in nonfinite contexts, but like an I with respect to do
support. Specifically, auxiliary have, like auxiliary do, shares all the morphological
properties of its main verb counterpart. In addition, it can appear in nonfinite contexts
(unlike auxiliary do). With respect to do support, however, auxiliary have differs from its
main verb counterpart and patterns together with the modals and auxiliary do. The
complex behavior of auxiliary have can be captured by saying that it moves from V to I
in the derivation of a sentence (see Chapter 6 for detailed discussion of V-to-I
movement).
(29) and (30) show that auxiliary have, like auxiliary do (cf. (18)), behaves
morphologically like its main verb counterpart in having an -s form.
(29) a. Auxiliary have
b.
(30) a. Main verb have
b.
I have adopted two cats.
She ha-s adopted two cats.
I have two cats.
She ha-s two cats.
Auxiliary have differs from auxiliary do (cf. (22)) and resembles main verb have in being
able to appear in nonfinite contexts.
(31) a. Auxiliary have, to infinitive
b.
after modal
c.
gerund
(32) a. Main verb have, to infinitive
b.
after modal
c.
gerund
They claim to have adopted two cats.
They must have adopted two cats.
I do not regret having adopted two cats.
They claim to have two cats.
They must have two cats.
I do not regret having two cats.
On the other hand, just like auxiliary do (cf. (26)) and in contrast to main verb have,
auxiliary have is ruled out in do support contexts.
(33) a. Auxiliary have, after emphatic do * He does have adopted two cats.
b.
negative
* He doesn't have adopted two cats.
c.
question
* Does he have adopted two cats?
(34) a. Main verb have, after emphatic do He does have two cats.
b.
negative
He doesn't have two cats.
c.
question
Does he have two cats?
Be (auxiliary and main verb)
The examples in (35)-(40) illustrate the behavior of auxiliary be, which is used to form
the progressive (is coming, was dancing) and the passive (is abandoned, was sold) in
English. Auxiliary be behaves just like auxiliary have. In particular, it has an -s form
(irregular though that form is), and it can appear in nonfinite contexts, but it is excluded
from do support contexts. As a result, auxiliary be can be treated just like auxiliary have:
as belonging to the syntactic category V, but moving from V to I in the course of a
derivation.
Main verb be differs from main verb have and main verb do in behaving exactly like
auxiliary be. In other words, main verb be is the only main verb in modern English that
moves from V to I.
(35) a. Auxiliary
be,
b.
non-third
person
third person
I am learning Spanish; I am invited to the ceremony.
She i-s learning Spanish; she i-s invited to the
(36) a. Main verb
be,
b.
(37) a. Auxiliary
be,
b.
non-third
person
third person
to infinitive
c.
(38) a. Main verb
be,
b.
(39) a. Auxiliary
be,
b.
gerund2
to infinitive
c.
(40) a. Main verb
be,
b.
c.
after modal
ceremony.
I am happy.
She i-s happy.
They claim to be learning Spanish; they claim to be
invited to the ceremony.
They must be learning Spanish; they must be invited
to the ceremony.
I don't regret being invited to the ceremony.
They claim to be happy.
after modal
They must be happy.
after emphatic * She does be learning Spanish; she does be invited to
do
the ceremony.
negative
* She doesn't be learning Spanish; she doesn't be
invited to the ceremony.
question
* Does she be learning Spanish? Does she be invited
to the ceremony?
after emphatic * She does be happy.
do
negative
* She doesn't be happy.
question
* Does she be happy?
Summary
The table in (41) provides a synopsis of the morphological and syntactic properties of the
items discussed here, arranged from most to least verb-like. As is evident from the table,
the syntactic category of an item depends on whether it is the verb-like or the modal-like
properties that predominate.
Be and auxiliary
Ordinary verb have
Auxiliary do
(41)
Modal
Has -s form
yes
yes
yes
no
Occurs in
nonfinite
contexts
yes
yes
no
no
Occurs with
do support
yes
no
no
no
Syntactic
category
V
V
I
I
Notes
1. More precisely, we must distinguish between form (morphology) and meaning
(reference). Ordinarily, forms with past-tense morphology are used to refer to an event or
state prior to the time of speaking. However, it is possible in English to use past-tense
forms to refer to events or state contemporaneous with a reported time of speaking; this is
the so-called sequence-of-tense phenomenon in reported speech, illustrated in (i).
(i) a. Direct speech:
She said, "They make too much noise."
b. Reported speech: She said that they made too much noise.
As is evident from (ii) and (iii), can, may, shall, and will continue to maintain a
productive morphological relationship with could, might, should, and would, respectively,
in sequence-of-tense contexts.
(ii) a. Direct speech:
b.
(iii) a. Reported speech:
b.
She said, "That may be so."
He told us, "You won't last long."
She said that might be so.
He told us that we wouldn't last long.
Nevertheless, in keeping with the point made in the body of the text, the morphological
relationship between the modals in (ii) and their counterparts in (iii) is purely formal,
lacking the referential underpinning evident in (iv).
(iv) a. They make too much noise.
b. They made too much noise.
We thank Aaron Dinkin for drawing our attention to the sequence-of-tense phenomenon.
2. For reasons not well understood, gerunds of progressive forms, as in (i), are
unacceptable.
(i) * I like be-ing learn-ing Spanish.