Expressing certainty and uncertainty

I beseech you, in the bowels of Christ, think it possible that you may be mistaken.
(Oliver Cromwell to the synod of the Church of Scotland on August 5, 1650)

doubt

Expressing certainty and uncertainty is a key communicative language skill and needed by learners at all levels of competence. Hedging and vague language are allied concepts so they are also dealt with here.

There are times when we don't want to state things definitely and clearly. What are the possible reasons for that? Think for a moment and then click here.

We really are uncertain
We are being deliberately vague
We don't want to appear too sure of ourselves and elicit antagonism

Downplaying certainty is called hedging.

Here are some examples of what this guide is about.
Can you spot:

The parts of the following in which the speakers / writers are being sure or being vague or uncertain?
The way they are doing it – i.e., the linguistic realisation of certainty, hedging and vagueness?

When you have an answer to a. and b. above, click on the to reveal some comment.

She seems to be upset.	She seems* to be upset.* The use of pseudo-copular verbs such as seem, appear, looks (like) etc. is a common strategy which expresses some doubt about the truth of a proposition.
He tends to be rather rude. I assume John will be late.	He tends to be rather rude. I assume John will be late. The use of so-called introductory verbs such as tend, assume, believe, suggest and so on is another common strategy to signal uncertainty of the truth of a proposition. The use of tend, in particular, is very common indeed and rarely taught. In British English it also takes the place of expressing current or past habit (would / used to) as a way of sounding less certain. Compare: We used to have lunch on the terrace (always) We tended to have lunch on the terrace (sometimes) We don't go to the cinema much (never) We tend not to go to the cinema much (rarely)
That'll be the postman. That might be them now. That could be the case.	That'll be the postman. That might be them now. That could be the case. Modal auxiliary verbs are used frequently to express various levels of certainty. How certain the speaker sounds is often dependent on stress and intonation rather than the intrinsic concept of the modal itself. Compare, e.g., That must be him ↓ (falling intonation = almost sure) That must* be him* ↑ (rising intonation = certain) You could be right ↓ (falling intonation (probably are)) You could* be right ↑* (rising intonation = but may well not be)
I'll certainly try. He'll probably be late. You are conceivably wrong.	I'll certainly try. He'll probably be late. You are conceivably wrong. These are modal adverbs (acting as adjuncts) and there are plenty of them in English which imply various levels of certainty, doubt and likelihood. Fronting the adverbs has a major effect because it marks them for emphasis. Compare, e.g., Probably, we'll get it done We'll probably get it done. Clearly, you are wrong. You are clearly wrong.
I often think he's a bit too clever. I sometimes feel he's deliberately unpleasant.	I often think he's a bit too clever. I sometimes feel he's deliberately unpleasant. Here two things are happening: The speaker is using a projecting mental process verb. There are lots of these including believe, feel, guess, consider etc. and they all refer to the speaker's certainty. The speaker is making the comment less definite by the use of time adverbs, specifically frequency, here. Other examples include (in)frequently, seldom, usually etc.
He is certain to be there. It is possible it will be too expensive. There are sure signs of improvement.	He is certain to be there. It is possible it will be too expensive. There are sure signs of improvement. Modal adjectives like these are used in a similar way to modal adverbs. They express both certainty (sure, certain etc.) and uncertainty (possible, probable, conceivable etc.) and are frequently used with existential It and There sentences as in the second two examples.
There's a strongish possibility that he won't come. There an outside chance that he will arrive on time. There's a reasonable likelihood that she'll be late.	There's a strongish possibility that he won't come. There an outside chance that he will arrive on time. There's a reasonable likelihood that she'll be late. Modal nouns like these are almost always qualified in some way with an adjective which either makes them more or less certain. Collocation is an issue because one can have a strong possibility but a weak possibility is at least unusual. Similarly, outside chance is the antonym of good chance (not bad chance). We frequently use the -ish* suffix in spoken English to downplay the adjective modifier.
That's going to be a bit hard to do. He's inclined to be a tad sure of himself. That's a little too much. There are a few new ideas here.	That's going to be *a bit* hard to do. He's inclined to be *a tad* sure of himself. That's *a little* too much. There are *a few* new ideas here. These are vague quantifiers or partitives (more below) and are very common in softening the directness of what is said. Learners of English rarely use them effectively. In the second example, the speaker combines the vague quantifier with an introductory verb, inclined to. That's quite common.

More detail and exemplification follows.

Modality

Expressing uncertainty or certainty using modal expressions (not just modal auxiliary verbs) is referred to as epistemic modality. The term comes from the Greek word for knowledge (ἐπιστήμη, epistēmē). We are expressing our view of the truth of a proposition on a scale of 0% possibility to absolute certainty.
A fuller guide to epistemic modality is linked in the list of related guides at the end.

Examples above of modal auxiliary verbs doing this job are:
That'll be the postman.
That might be them now.
That could be the case.

pure or central modal auxiliary verbs

A number of pure or central modal auxiliary verbs can function to express epistemic modality. They do this in three ways:

	Positive	Negative
Expressing the possibility that something is true	It can be cold here in February	It can't be raining again
	I could be delayed by the weather	He couldn't have got lost
	He may be late	He may not come on time
	That might be the postman at the door	That might not be what you imagine
Expressing the logical necessity that something is true (not always with absolute certainty)	That letter must be from the bank	It can't be from your mother It couldn't be from your mother
	If it's at Platform 5, it should be the London train	If it's at Platform 5, it shouldn't be the one we want
	She ought to be at home by now	That's oughtn't to be our train. It's on the wrong platform
Expressing a prediction that something will be true	That will be the 6:30 bus	That won't be him ringing. It's too early.
	That would be the warmest place to sit	That wouldn't be a very comfortable bed.
	Because John is such a bad player, I shall beat him easily	Because he plays well, I shan't beat him easily.

Notes:

ought to is often considered a semi-modal auxiliary verb and is, in fact, the only one that can be used to express epistemic modality (dare, used and need cannot be used this way). The negative use of ought to is rare.
shall is quite rare, even in BrE.
an alternative to must in this sense is have (got) to (e.g., in That has to be the right bus) but there is no negative, can't and couldn't being preferred. The insertion of got strengthens the sense of certainty.

marginal modal auxiliary verbs

(For a bit more, see the guide to semi- and marginal modal auxiliary verbs, linked below.)

A few of these can express some sense of epistemic modality.

seem to: That seems to be the train we need (but it might not be)
tend to: The train tends to be busy on Fridays (but that isn't a fixed rule)
be likely to: That's likely to be a busy restaurant (but we may be lucky)
be supposed to: He's supposed to be the manager (but I'm not sure he knows what he's doing)

modal adverbs, adjectives and nouns

modal adverbs

There were examples of these above using certainly, probably, clearly etc.
Other examples are:

assuredly
avowedly
certainly
clearly
decidedly
definitely

evidently
incontestably
incontrovertibly
indeed
indisputably
indubitably

inevitably
manifestly
maybe
necessarily
obviously
of course

patently
perhaps
plainly
presumably
probably
really

surely
unarguably
unavoidably
undeniably
undoubtedly
unquestionably

As in, e.g.:
    That is indisputably false
    She is plainly correct
    They are undeniably better players
    That is decidedly unlikely
etc.

modal adjectives

There were examples above to which we can add

absolute
certain
clear
complete
definite
likely

plausible
possible
potential
probable
total
unlikely

These adjectives modify modal and other nouns as in, e.g.:
    There's a clear chance of rain
    It's a possible issue
    I consider it a total impossibility
    We see a definite opportunity here, but also a potential problem
etc.
Modal adjectives frequently appear with the dummy it and existential there constructions as in the first of these two examples.

modal nouns

There were examples above using possibility, chance and likelihood to which we can add opportunity and certainty but almost no others. As was noted, these are almost always (but not always) modified in some way as in e.g.:
    There's a complete certainty that he'll be late
    There's an outside chance she'll be on time
    This is a definite opportunity
etc.
Again, the dummy it and existential there structures are common.

finite clauses

As we saw with the examples using tend and assume, a number of verbs in finite clauses can be used to express epistemic modality. Many of these verbs act as copular forms and include but are not confined to:

They suspected she was the thief
I assume he's coming
We think it's going to be OK
It appears to be the part we want
I imagine it'll be late
I guess he's her brother

Vague language

In addition to all of the above, English has a number of ways to express vagueness. For example, we can say
    Thirty people came to the party
or we can hedge our bets and say something like
    Around thirty came
or
    Near enough thirty people came
etc.
Here are examples of vague language. Can you classify them?
Click here when you have a mental list of three categories.

I want to get some eggs, milk and other breakfast stuff.
There are seats for up to twenty people here.
Pass me the thingy on the left.
It's got a certain je ne sais quoi about it.
I don't want to get people into rows and the like.
There are over twenty of them.

list completers: Examples 1 and 5 contain list completers. Other examples are
    and so on
    and suchlike
    or things like that
    and people of that ilk
etc.
We use these frequently in spoken language because the hearer shares the idea and we don't need or want to be explicit (or boring and loquacious).
    etc.
is a common list completer in both spoken and written language when the speaker / writer is sure that the hearer / reader can complete the list independently.
vague quantities: Examples 2 and 6 contain vague quantities. These aren't as simple as they appear although they are equally, if not more, common. For example:
    Up to thirty people are coming
implies no more than thirty but also will mean not less than nearly thirty. It does not mean two or three people are coming although logically, there is no reason why it shouldn't.
    Over twenty people are coming
certainly means more than twenty but it does not include the idea of 20,000 people.
    Around 600 tickets were sold
implies a quantity from 500 to 700.
Across languages, exactly what is intended with vague quantifiers is variable so a little time take to explain what they imply in Anglophone cultures may be useful.
placeholders and general nouns: Examples 3 and 4 contain placeholders. Of great help to learners of English, who may have limited vocabularies, is the ability to use placeholders. They come in two flavours:
placeholders used to express the fact that the speaker has no immediately available word for something. These include words like
    thingy
    doobrie
    thungummy
    thingummybob
    whatsit
    whatsitsname
    stuff
    gubbins
and many others. They are always informal and generally confined to spoken language in which the speaker cannot pause to retrieve the correct term.
general partitive nouns such as
    bit
    piece
    part
    portion
can be used when the 'right' term, i.e., the typical or restricted partitive is not available or can't be recalled. In this way,
    a bit of cake can replace a slice of cake
    a bit of sand can replace a grain of sand
    a piece of glass can replace a pane of glass
etc.
Again, the use of general partitives rather than limited or restricted partitives is usually more informal.
There is a guide partitives and classifiers, linked below.

Teaching this area

This is an area at which learners of the language tend to fall into two camps: those who preface all remarks with Perhaps or Maybe and sound overly tentative and unsure and those who fail to use the language of uncertainty effectively to soften what they say. It therefore demands our attention.

As we saw above, the area is complex and there is a range of ways to express certainty, uncertainty, vagueness and deliberate hedging. We can, if we are not careful, overwhelm our learners so the area needs to be approached piecemeal, one or two structures at a time.

Raising awareness

A simple approach is to start with recognition of the speaker's level of certainty. Like this:

For modal auxiliary verbs:
Put a tick in the right box.

Statement	Sure	Maybe	Very unsure
That will be the postman at the door.
That could be the postman at the door.
That might be the postman at the door.

For verbs:

Statement	Sure	Maybe	Very unsure
I assume he's coming.
I know he's coming.
I think he's coming.
I suspect he's coming.

For adverbs:

Statement	Sure	Maybe	Very unsure
He's probably here already.
He's certainly here already.
He's possibly here already.
He's definitely here already.

The same kind of approach can, clearly, be taken for the other strategies in the discussion above.

For vague language we can take similar awareness-raising approaches. For example,

For quantities

Statement	20-70	40-60	49-51
Around 50.
Nearly 50.
Less than 65.
Over 40.

For placeholders


The glass thingy.
The green whatsitsname.
The round doobrie.

For list completions

Which endings are possible?	other stuff done.	some other people.	lots of other stuff.	some other things done.
I need to get some shopping and
He brought his friends and
She got her hair and
They used my car and

Noticing

Almost all texts and dialogues (if they are reasonably authentic) will contain examples. Advertising is a particularly rich source. For example:

What are you actually getting?
Up to 20% off! Over 50 in every packet! More than 20 different uses!
Highlighting examples helps at first to get people alert to the types of language.
I had a great birthday party. All my friends from Uni and Margate came and the family were there, too, as well as some other people I didn't know. There might have been as many as forty of us but certainly more than 30. We had planned on food for up to 25 but knew there was a good chance we'd have to get a bit more in. I didn't see your brother but it's perfectly possible he was there, isn't it? After all, he usually doesn't miss a good opportunity for free food so I assume he was there. It seems everyone else was!

Practising

Rephrasing is helpful. For example:
Over fifty but not as many as 60 can be rephrased as: at least fifty
It's an object whose name I don't know for opening tins can be rephrased as: the thing to open tins
I am only 20% sure he is here can be rephrased as: he might be here
I am almost sure it is possible can be rephrased as: it should be possible

Varying the expressions to see what effect it has is also helpful. For example:

What is the difference between these three paragraphs. Focus on the language in black type.
Talk to your partner to decide what you think.

All my friends from Uni and Margate came and the family were there, too, as well as some other people I didn't know. There might have been more than forty of us but certainly not more than 60. We had planned on food for up to 25 but knew there was a fair likelihood we'd have to get some more in. I didn't see your brother but it's perfectly possible he was there. After all, he rarely misses a good opportunity for free food so I assume he might have been there. It seems certain that everyone else was!

All my friends from Uni and Margate came and the family were there, too, as well as some others There might have been nearly forty of us but certainly over 25. We had planned on food for approximately 25 but knew there was some chance we'd have to get a bit more in. I didn't see your brother but there's a reasonable chance he was there. After all, he barely ever misses an easy chance for free food so I imagine he could have been there. It is certain that everyone else was!

All my friends from Uni and Margate came and the family were there, too, as well a few mates. There might have been over forty of us but certainly more than 30. We had planned on food for almost 25 but knew there was a good chance we'd have to get lots more in. I didn't see your brother but there's an outside chance he was there. After all, he never misses a chance of free food so I get the feeling he must have been there. It appears everyone else was!

Using realia in lessons can be productive if you are sure that the class don't know the proper words for them. That means they are forced into using placeholders to refer to them. Commercial catalogues are a good source of pictures if you can't lay your hands on the objects.
Another practice routine is to ask for opinions in areas where people have very little experience. For example,
How do you think the Inuit spend the summers?
What would you do on holiday in Guatemala?
Where would you buy X in country Y?
and so on.
This will work much better if:
1. You have presented and practised some of the hedging strategies covered above.
2. You insist on the use of at least two of them in every response.
3. You forbid all comments beginning with perhaps or maybe. You can ban the words altogether, of course.

Academic English

If your learners are studying English for Academic Purposes, they will need to work hard on getting the right tone in what they write. There is a convention, for example, that we rarely write, e.g.:
It is certainly obvious that ...
preferring, in academic language, something like
It seems strongly arguable that ...
Stating that something is true simply challenges the reader to disagree or think of a counter example.
This is not the place for more detail but the same strategies that have been outlined here for spoken language will apply equally to formal, written prose.
This is especially true for the use of modal auxiliary verbs, modal nouns, adjectives and adverbs and the use of appropriately modest copular verbs, replacing the certain be with less assertive verbs such as seem.
There is a guide to using hedging language in EAP, linked below.

Related guides:
partitives and classifiers	for a guide to general, restricted and typical partitives
epistemic modality	the guide which considers the area of expressions of likelihood
semi- and marginal modal auxiliaries	for the guide to how these are formed and what they mean
non-modal auxiliary verb modality	for more on how we use adverbs, nouns and adjectives to express the ideas covered here
hedging in EAP	for the guide to how good academic writing relies on hedging appropriately

There a short test on some of this if you want to do it.