Modality without modal auxiliary verbs

modality

These two sentences express almost the same meanings:

It is probably verifiable that there is no necessity to use a modal auxiliary verb to express modality (so it's avoidable).
It may be the case that you don't have to use a modal auxiliary verb to express modality (but you can).

All the words in black express some form of modality. This guide is concerned with ones such as those in the first sentence, i.e., words which express modality of some sort (obligation, deduction etc.) but which are not modal auxiliary verbs (as in the second sentence).

It would be helpful but not essential if you follow the general guide to types of modality (new tab) before tackling this one. If the terms deontic, epistemic, dynamic and alethic modality mean little to you, then it is almost essential to do so.
To remind you, here are the four main types of modality exemplified with various realisations of the modal expression:

epistemic modality: comment on the truthfulness or otherwise of a proposition as in, e.g.:
    He is certainly at home
    She can't be there by now
    That seems unlikely
deontic modality: comment on obligation, duty or necessity as in, e.g.:
    You are required to show your passport
    Visitors must wear a badge at all times
    There's no necessity to buy a ticket in advance
dynamic modality: expressing ability or willingness as in, e.g.:
    I am unable to pay
    She said she's happy to help
    He has a knack of making friends
alethic modality: expressing timeless inevitable truths as in, e.g.:
    Water must boil at that temperature
    The laws of physics do not allow speeds faster than the speed of light
    Sound travels more slowly than light

Website alert:

This is a poorly understood area. Some websites will seek to persuade you that, for example, the word just in something like
I'll just talk to him
is a modal adverb.
It isn't, of course; it's a downtoner and working in the same way as thousands of other adverbs may be used to modify lexical or main verbs. Here we are concerned to analyse those words which really do work as modality carriers in one way or another. An example of a true modal adverb is the word fairly as in, e.g.:
I'm fairly certain I know him.
and that sentence also contains a modal adjective, certain.
There will be many more examples in what follows.

Three classes of modal words

There are examples of all three of these in the first sentence above:

probably: an adverb (an epistemic use to do with the certainty of something being true)
verifiable and avoidable: adjectives (the first is epistemic, the second deontic, expressing a lack of obligation)
necessity: a noun (a deontic use)

A fourth class of modal words which are not modal auxiliary verbs will be discussed here. These are sometimes known as marginal modal auxiliary verbs and include, for example, be about to. They are not semi-modal auxiliary verbs, of course.

Perceptions of reality

As you will know if you have a grasp of modality at all, modal expressions relate to the speaker / writer's view of reality. Non-modal auxiliary verb modality is no exception.

Perceptions of reality concern:

How likely one understands, given available evidence, that an event of a state is real (epistemic modality). For example:
That's probably right
I believe he's a fool
How necessary one understands a state or action to be (deontic modality). For example:
I'm ordering you to stay
There's no need to argue with me
How able or willing someone is to do something (dynamic modality). For example:
She has the skills to help
I'm prepared to try
Whether something is true or false without reference to current conditions (alethic modality). For example:
E=mc²
Boyle's Law states that at a constant temperature, the pressure of any mass of a gas is inversely proportional to its volume

A great many of the ways we use to express modality without using modal auxiliary verbs are adverbs and/or adjuncts and disjuncts. A fair few are, however, adjectives and a significant number are nouns. Many are derived or derivable from verbs or from each other.

The variety of non-modal-verb modal expressions

Some examples will help to define the area, some simple, some not so simple.

Example	Type of modality	Alternative modal-verb expression	Notes
As a matter of fact, it's your turn to wash up	epistemic and deontic	You ought to wash up	The adjunct As a matter of fact expresses the speaker's view of the truth of the statement. The noun phrase your turn expresses the speaker's view of another's obligation.
I was unavoidably delayed by the need to see the doctor	deontic	I had to see the doctor so couldn't help being late	The adverb unavoidably and the modal noun need both express the speaker's view of the level of obligation.
I don't dispute that you think you saw a unicorn but it appears unlikely to me	epistemic	You may think you saw a unicorn but you couldn't have	The verb dispute in the negative expresses the speaker's surety that you are telling the truth but the copular verb appears with its adjective complement unlikely expresses the speaker's doubt.
Technically, that's undeniable	epistemic	It might well be true	The disjunct technically expresses the speaker's viewpoint and the adjective undeniable expresses a degree of certainty.
I assure you that I am totally certain to get it finished	epistemic and dynamic	I'll definitely be able to finish	The speaker is expressing certainty, with the verb assure, the adverb totally and the adjective certain and the whole sentence refers to personal ability and is, therefore, dynamic modality.
Hypothetically, much of what is suggested is possibly verifiable but there's an undoubted need for more evidence	epistemic and deontic	It might be true but we must have more evidence	The disjunct hypothetically expresses the speaker's uncertainty of the truth of a suggestion and the verb suggest itself adds more uncertainty. The adjective phrase possibly verifiable adds weight to the uncertainty. The noun phrase undoubted need expresses a strong obligation.
He's definitely arrived by now	epistemic	He must have arrived by now	The adverb definitely expresses the firm deduction.
I am willing to do that	dynamic	I can do that	The verb will may express either futurity or volition (willingness). Here, it expresses the latter.
Are you able to come?	dynamic	Can you come?	The adjective able is very commonly used instead of the modal auxiliary can.
All stars eventually die	alethic	All stars must die	The use of the present simple tense often expresses this kind of modality without the need for any adverbial or auxiliary verb.

Here's an incomplete list of the ways modality can be achieved in English without the use of modal auxiliary verbs.
Note, though, as in some of the examples above, these are often used in conjunction with modal auxiliary verbs to heighten or diminish the strength of what is being said / written.
We can get, therefore, examples such as:
    I'm sure he must be aware of that
    It's manifestly the case that he can't do the job
    It is essential that he must do that
etc.

Modality	Verb	Adjunct / Conjunct / Disjunct		Adjective		Noun	Notes	Examples
epistemic (more sure)	assure observe manifest prove show avoid deny doubt undermine verify	actually as a matter of fact assuredly certainly clearly definitely doubtlessly evidently in fact in point of fact incontestably indisputably indubitably ineluctably inescapably inevitably	literally manifestly observably obviously patently plainly statistically sure technically totally transparently truly unarguably unavoidably undeniably undoubtedly unquestionably verifiably	actual factual believable certain evident incontestable indisputable indubitable ineluctable inescapable inevitable literal manifest observable obvious patent plain statistical	sure technical total transparent true unarguable unavoidable undeniable undoubted unquestionable verifiable	assurance belief certainty incontestability indisputability indubitability ineluctability inevitability observation unavoidability verifiability	The items heighten the sense of certainty. Some work in a way similar to the use of must, cannot or should to express logical deduction of a fact. Adjectives used in this way can be nuanced with the use of a variety of copular verbs: It is unquestionable, seems unquestionable, appears unarguable etc.	This is the actual bed that the Queen slept in It is actually more difficult than you think That is incontestably the result It is statistically the case that A sure outcome is disaster His dishonesty is a transparent fact I do not deny that Plainly, that is not the case.
epistemic (less sure)	allege appear argue believe credit debate defend dispute hypothesise	allegedly apparently arguably at first glance at first sight believably conceivably credibly debatably defensibly disputably fairly hypothetically loosely ostensibly perhaps	plausibly positively possibly presumably probably purportedly putatively quite rather really reportedly reputedly scarcely seemingly surely without (a) doubt	alleged apparent arguable conceivable credible debatable defensible disputable hypothetic likely ostensible plausible positive possible	presumable probable purported putative really reported reputed rumoured scarcely seeming sure unlikely	allegation appearance argument debate defence dispute evidence hypothesis likelihood possibility probability rumour	The items weaken the truth of the statement and function in the way that may or might are used to express uncertainty. Compare, e.g., They may be related. Adjectives used in this way can be nuanced with the use of a variety of copular verbs: It is disputable, seems unlikely, appears credible etc.	He is allegedly very rich The alleged terrorist was arrested That's an allegation I deny At first glance, they seem related It's conceivable that the facts are connected It's my belief that he's French You say so but it's debatable, of course Loosely, it's a kind of short circuit There's a rumour that he's married
deontic	allow approve authorise command compel conform force instruct let need obey oblige order permit tell tolerate	advisably compulsorily necessarily needlessly obligatorily pointlessly unnecessarily		compulsory essential liable necessary needless obligatory permissible unnecessary		compulsion force conformity necessity need obligation permission	There are fewer deontic expressions but they work in the same way as verbs like should, ought to, must and have to.	She's obliged to stay It's needlessly complicated I command obedience I was compelled to join
dynamic	accomplish achieve collapse demonstrate die fail flourish manage offer propose prosper show succeed thrive work	ably (in)effectively fruitfully fruitlessly (un)productively (un)successfully		*(un)able (in)effective fruitful fruitless (un)productive (un)successful		ability accomplishment achievement demonstration failure success	There are fewer dynamic expressions because this is an area where modal auxiliary verbs are often preferred. They include: can(not), could, be able / unable to.	The experiment accomplished its aims The data demonstrated the success of the approach The organisms survived and flourished The program works insofar as ...
alethic	allow compel conform force involve mean need obey oblige permit	certainly compulsorily of necessity in principle incontestably inescapably inevitably necessarily observably unavoidably		certain constrained incontestable indisputable indubitable ineluctable inescapable inevitable necessary observable required unavoidable		assurance certainty constraint fact falsehood incontestability indisputability indubitability ineluctability inevitability law necessity observation prerequisite principle requirement truth unavoidability	There are fewer alethic expressions because this is an area where modal auxiliary verbs are often preferred. They include: cannot (negative only) must (positive only).	A prerequisite for inclusion in the survey was ... The principle underlying the categorisation is ... One unavoidable constraint is ... By the laws of physics ... Of necessity, ...

* The adjective (un)able is very commonly used to express dynamic modality in the past and future as well as the present because the verb can is defective having only could as a restricted-use past form and no future form with will at all.
If you would like to have that table as a PDF document, click here.

Collocation and colligation

Collocation, as you are probably aware, refers to the tendency for certain words to co-occur. Colligation refers to the fact that certain sets of words tend to co-occur with certain grammatical structures.

Collocation
Because these expressions involve verbs, adverbs, adjectives and nouns, it is rich ground for collocational phenomena.
1. verb + noun, for example:
  1. You can't
    *prove the belief
    but you can
    prove the verifiability
    of something.
  2. You can't
    *debate the argument
    but you can
    debate the evidence
2. adverb + adjective, for example:
  1. We can allow
    an arguably probable outcome
    but not
    *a debatably disputable argument
  2. We can't have
    *a necessarily needless action
    but we can allow
    a necessarily essential action
3. adjective + noun, for example:
  1. We can have
    a manifest belief
    but not
    *a debatable rumour
  2. We allow
    needless force
    but not
    *obligatory compulsion
Colligation
Grammatically, many of these expressions behave rather differently. For example,
1. It is possible to say
  1. They allowed him to go
    but
    ?They allowed him to understand
    is a very rare construction because verbs like these (permit, allow, convince etc.) require dynamic uses of verbs as their complements.
2. Nouns like consequence or outcome are almost always found in the subject position so things like
  1. The consequence is predictable
    are quite common but
    ?It resulted in the consequence
    sounds unusual and clumsy.
3. We can have
  1. It is likely he'll be late
    It is probable he'll be late
    and we allow
    He is likely to be late
    but
    *He is probable to be late
    is not permitted by the rules of English structure.
4. Verbs of compulsion and permission are also tricky. We can have
  1. They made me go
    and
    They allowed me to go
    but in the passive these become
    I was made to go
    and
    I was allowed to go
    with an intrusive and non-intuitive to-infinitive for the verb make
  2. It's fine to have
    They let him stay
    but an attempt to make a passive from that fails because it gives the unacceptable
    *He was let stay.

These expressions must, therefore, be presented with co-text as well as context if our learners are going to have the data to allow them to produce colligationally and collocationally acceptable English.

Marginal modal auxiliary verbs

These are sometimes called semi- or quasi-auxiliary verbs.

In addition to the verbs in the second column of the main table above, a number of verb phrases are often used to express modality. The meanings of many of them are covered in the guide to semi- and marginal modal auxiliary verbs, linked below, but here's a short list with a few examples of their use. Many are almost confined to passive-voice use in these meanings.

Verb phrase	Type of modality	Example
be to	deontic	You are to come at 6
be (un)able to	dynamic	I am (un)able to help
be certain / sure to	epistemic	He's certain to be late
be meant to	deontic	I'm meant to be at a meeting
be due to	epistemic	The problem is due to the damp
be forced to	deontic	I was forced to leave
be supposed to	deontic	You aren't supposed to be here
be bound to	epistemic	It's bound to rain
be bound to	alethic	Increasing the size of a sealed container is bound to lower the pressure
be likely to	epistemic	He's likely to get annoyed
mean to	dynamic	I mean to talk to him
seem to	epistemic	It seems to be broken
tend to	dynamic	We tend to stay at home now

Nearly all these meanings can be encoded using semi- or central modal auxiliary verbs, of course, but some subtlety is lost in the process.
We have added be (un)able to to that list, too, because it is a very common adjectival way of expressing dynamic modality although it is sometimes treated (mistakenly) as a modal auxiliary verb in its own right.

Shades of meaning

For reasons which are historic more than rational, many teachers compel their learners to express their perceptions using modal auxiliary verbs rather than any other device. We get, therefore the admonition, for example, not to say:
Perhaps he is her brother
but to formulate that as:
He may / might / could be her brother

For learners whose first languages exhibit few or even no modal auxiliary verbs, that may be initially helpful. What is not in doubt is that it can also be restrictive and inhibiting.
It is clear from the above that using adverbs, adjectives and nouns to express modality allows for a great deal more in terms of subtle shades of meaning than the use of a handful of modal auxiliary verbs.
For example, it is difficult, using a modal auxiliary verb to convey the senses embodied in:
    That's your opinion although I find it disputable
which is not at all what's meant by, e.g.
    You may be right
    It's observably the case that she is becoming more demanding
which is not at all what's meant by
    She must be becoming more demanding
    I feel an obligation to him
which is almost impossible to render with a modal auxiliary verb such as need, should, ought to etc.)
and so on.

Spoken and written language

It is often averred that modal auxiliary verbs are more common in spoken than in written language.
That is true but the more important issue is why it should be true. Here's part of the answer.

In speaking, we have a number of quasi-linguistic resources to hand, not least of which are stress, tone, pitch and intonation. We can, for example, easily vary the meaning of:
I should be at a meeting (so I'm going)
to make it
I should be at a meeting (but I'm not going)
by stressing the modal auxiliary verb and using a rising intonation along the sentence.
The same trick can be performed with the whole range of modal auxiliary verbs in English (and any other language).

In writing, no such resources apart from using bold, italic or underlined fonts are available to us and in any formal kind of writing these are themselves severely restricted. Hence the need for a wide range of verbs, adjuncts, adjectives and marginal modal expressions to capture a more exact sense of what we mean.
In academic writing, this becomes seriously important because the difference between
    It is a verifiable fact
    It is arguable that
    It is transparently the case that
    There is some evidence that
etc.
is very important if the wrong message is not to be sent.
Relying on the narrow range of modal auxiliary verbs available in English would mean that an academic writer may easily be misinterpreted or even misunderstood. For example, stating:
    It must be the case that
when what is meant is:
    It is a defensible conclusion that
would be perilous.
This is, naturally, mainly important to show a suitable amount of hedging when expressing epistemic modality concerning the assumed truth of a proposition.

Teaching non-modal auxiliary verb modality

There are clearly some issues:

Level: Many of the non-modal-verb ways of expressing modal ideas are teachable and learnable at quite low levels. For example:
    It is possible that ... / Possibly, ...
    It is likely that ... / There's a good likelihood that ...
    It is probably that ... / Probably, ...
    It is sure that ... / Surely, ...
    They made me do it
    She allowed me to go
etc. are all accessible to lower-level learners.
However, other items are much more demanding:
    Without a shadow of a doubt ...
    Conceivably, but not verifiably ...
    Some dispute the truth of the hypothesis
    I was compelled to conform
    In conformity with your wishes ...
are clearly left to later stages and to higher-level learners.
Be selective, therefore.
Avoidance: It is probably true that learners whose first languages have a restricted range of modal auxiliaries are sometimes reluctant to use them and prefer expressions such as:
Perhaps, she'll come to the party (instead of She might come to the party)
or
That is probably not true (instead of That may well not be true)
However, the attempt to force expressions with modal auxiliary verbs instead is probably, a) doomed and b) unhelpful.
The fact is that non-modal auxiliary verb expressions are very common and carry more or less subtle meanings which cannot easily be expressed with a modal auxiliary verb. There is no good reason to suppose that they are somehow inferior.
Type of modality: In the large table above, the effort has been made to divide the expressions into the two main types of modality, epistemic, relating to the truth of a proposition and deontic, relating to the degree of obligation.
Not to do this when selecting items for teaching or explaining meaning is perverse and bewildering for learners. All types of modality can be expressed using these sorts of expressions:
    Deontic modality: I feel obliged to tell you that ...
    Epistemic modality: It is clear to her that ...
    Dynamic modality: I mean to get here early
    Alethic modality: A rectangle manifestly has four sides
but mixing them up in the same lesson is an unfocused approach which is unlikely to succeed.
Collocation and colligation: We saw above that these are significant issues in this area and that it is arguably essential to teach them not only in a context in which their meaning is clear but also with enough co-text for their collocational and colligational characteristics to be revealed. If we don't do this, our learners will be led into errors such as:
    *The result was the consequence that ...
    *He was let stay
    *The necessity was authorised
    *There is conceivable evidence that ...
etc.
Equivalence: We have seen that there often is no clear equivalence between a sentence using a modal auxiliary verb and one using an alternative expression. Sometimes, however, there is some sort of equivalence which can be exploited either to teach these sorts of terms or, in reverse, to teach the modal auxiliary meanings themselves. For example, the modal auxiliary verbs must, can't and couldn't when used epistemically to make a logical deduction such as
    That must be our bus
    That can't be the right platform
    That couldn't have been the only reason
can be replaced with a range of alternatives, each expressing a shade of certainty. For example:
    That is certainly the right bus
    There's a strong probability that this is the wrong platform
    At first glance, that wasn't the only reason
Getting learners to arrange these on a scale of certainty is productive.
The ability to vary the way certainty and obligation are expressed is a key skill.
Written English and English for Academic Purposes: There are guides on this site, linked below, to using hedging and modality in academic language and to using reporting verbs in EAP which express varying degree of certainty and assertiveness.
This area, too, is important for learners whose needs are to write and understand formal English whether in an academic or a professional setting. The ability to unpack what a writer really means by, e.g.:
It is arguably the case that we have verified the probability of ...
is very valuable, as is the ability not to sound overly assertive and sure of yourself.
Hiding from the area: Many teachers feel reluctant to tackle this area, preferring to stick to the certainties of using modal auxiliary verbs for these functions. That's a mistake because the area is accessible to a little analysis (see above) and can be handled right across the range of levels in the classroom.
It's also, of course, one that it would be perverse to hide from our learners.

Related guides
the modality map	for links to more guides in the general area
central modal auxiliary verbs	a traditional view taking each modal auxiliary verb in turn and identifying its function
semi-modal auxiliary verbs	which also considers marginal modal auxiliary verbs such as seem, tend, be about to etc.
types of modality	an overview of deontic, epistemic, alethic and dynamic modality
epistemic modality	modality for expressing the speaker's view of the truth or a proposition, i.e., likelihood
deontic modality	modality for expressing the speaker's view of obligation or its lack
dynamic modality	modality for expressing ability and willingness
multiple modalities	for the guide to how some of the above may be used to combine modalities
teaching modality	for some more ideas transferable to the analysis above
hedging in EAP	for an EAP perspective in these areas
reporting verbs in EAP	for an EAP perspective in these areas
modality and aspect	which considers modal auxiliary verbs with perfect and progressive forms and also some of the types of modality discussed here