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The Truth about MUST vs HAVE TO

22 stycznia 2018, poniedziałek,

I am going to describe a familiar situation that I have had with many people I know who use English as a second language.  We are sitting somewhere, perhaps a café, or a pub, or we have just finished a game of billiards and the person will look at their watch and say to me; “I must go home.”  It is difficult for me to think of any context where a highly fluent speaker of English would say this.  It just doesn’t sound correct. Young students often ask “What must we do for homework?” Also WRONG!  I see why students like it so much. MUST is easy. It doesn’t change for each person and it looks stunningly similar to the Polish ‘musieć’. Students are taught all kinds of nonsense about external and internal obligation – feeling that you need to do something versus having something dictated to you.  It is all a pile of rubbish.  The fact of the matter is ‘MUST’ as a modal of obligation is declining in common usage and teachers seem afraid to talk about it honestly.

© Mat Wright, British Council


He must be good if I am going to look after him. (Still sounds strange)

He plays in the National Orchestra?!?! He must be good.

Here we have two sentences containing the phrase ‘He must be good.’ Let us be clear that MUST is a modal verb in each instance but it clearly means something different in each sentence.

In the first – he has to be good – it is a modal of obligation.

In the second – I suppose he is good – probably / I can assume – it is a modal of probability

I will be discussing the use of MUST as an obligation for the rest of this blog. MUST as a modal of probability is a great modal and the popular usage of MUST in this context hasn’t changed over time so much.

ALSO, I will avoid discussing the super popular ‘I’ve gotta’ (I have got to do sth). It is widely used and behaves similarly to ‘HAVE TO’. If it helps you, every time I use ‘HAVE TO’ you can also read ‘I’VE GOT TO’

The Textbooks

Trigger Warning: A lot of what course books have been writing about this topic is outdated hogwash! This may upset some old-school traditionalists.

Supposedly, according to any number of course books – you choose;

MUST is used when the speaker believes it is necessary. i.e./ I must go home now. (I feel it is necessary)

HAVE TO is used when it is necessary because of external influences. i.e./ We have to go now. (It seems they are closing the restaurant.)

Curiously this internal / external element disappears in the negative and the past!


Present We must leave. We have to leave.
Past We had to leave We had to leave.
Question Do we have to leave? Do we have to leave?
Negative Present We didn’t have to leave.* We didn’t have to leave.

*We MUSTN’T leave is not the negative obligation. It suggests NOT being allowed to leave = We can’t leave.

It is very curious indeed how the internal and external obligation factor seems to vanish in other contexts.  “I’m sorry about heading out so early last night. I had to leave.” (Did the speaker feel it was necessary or did he have some external obligation??)


The truth of the matter is that ‘MUST’ is rapidly declining in common usage over the past few decades as noted by Dr. David Crystal in his plenary at IATEFL Birmingham in 2016. (The same goes for ‘SHALL’ by the way.)

‘MUST’ as a modal of obligation is used mostly in writing and formal contexts exclusively.  A lot of school rules and regulations might use ‘MUST’.  A sign posted to a door might read. ALL VISITORS MUST WEAR AN ID BADGE. These contexts are all very legitimate and correct.  However, in modern spoken, colloquial English, people are much more likely to use ‘HAVE TO’ for any and all expressions of obligation. Even if I read a sign that said “ALL VISITORS MUST WEAR AN ID BADGE” I would probably call up my boss and say, “Geez, it says here on a sign that I have to have an ID badge! Where do I get one?”

To avoid sounding strange and not-so-fluent one should avoid using ‘MUST’ as an obligation in a spoken context.

EXCEPTION – It is true that in order to sound very hyperbolic and emphatic you could say, “Bob, you absolutely MUST come to my party next week.”  Here it is understood that you are being emphatic and the speaker is almost lampooning the language itself.

The description above describes the actual reality of ‘MUST’ as a modal of obligation.  Do you have any recollections about what you were taught at school? Have you ever felt that the course books never reflected what was happening in real life? Let us know in the comments below

Trigger warning – a trendy expression to alarm the listener that a potentially offensive or controversial opinion is coming up.

Hogwash – nonsense, rubbish, not true

To lampoon – to mock, to ridicule, to satire


Komentarze: 4

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  1. Hi Ricky!

    The Textbooks
    Trigger Warning: A lot of what course books have been writing about this topic is outdated hogwash!
    Supposedly, according to any number of course books – you choose;

    MUST is used when the speaker believes it is necessary.

    HAVE TO is used when it is necessary because of external influences.


    Have to and must are both used to express obligation. There is a slight difference between the way they are used.
    Have to shows us that the obligation comes from somebody else. It’s a law or a rule and the speaker can’t change it.
    Must shows us that the obligation comes from the speaker. It isn’t a law or a rule.

    Is British Council wrong? Is it outdated hogwash? Well, I’ve trusted them so far:)
    Any comments?



  2. Hi Zbyszek,

    As I mentioned in the blog “How English has Changed in Recent Years” language is a very dynamic thing and changes relatively quickly with time.

    I do think that the learnenglish.britishcouncil.org website is following a slightly more traditional explanation of the difference between MUST and HAVE TO whereas the blog tries to give a more current real ‘descriptive grammar’ explanation.

    I would also refer you to Dr. David Crystal’s plenary https://iatefl.britishcouncil.org/2016/session/plenary-david-crystal and the precise minute is 26min 30 secs where he discusses this trend in much more detail.

    In time we may have to restructure what was said on the learnenglish website but it does reflect that there is only a slight difference between these forms and avoids the whole written vs spoken English side of things.


  3. Hey Ricky,

    I see no comments are possible on your latest – the St Patrick’s day piece.

    That piece has such glaring mistakes and inaccuracies I almost suspect comments have been disabled on purpose. Starting with ‚bottom’s up’ (o rly? Whose bottom? Or have you come down with apostrophosis?), then with the pint definition (a pint is 568 ml, or. 0.568 litre), and culminating with an interesting definition of shandy and keg. I expect you were conducting intensive research the night before you wrote that.

  4. Hello,

    First of all, we definitely corrected the apostrophe problem in ‘Bottoms up’ – well spotted. I hope you can forgive my foolish mistake. I remind you that I am, after all, just a human being.

    As for the other issues;

    We stand by the definition of ‘keg’ – “A keg is a small barrel.” = Wikipedia.org

    A ‘shandy’ according to Wikipedia.org – Shandy is beer mixed with a soft drink, such as carbonated lemonade, ginger beer, ginger ale, apple juice, or orange juice. So I have no idea why you seem to take issue with that one either.

    A ‘US pint’ = 473ml which will often just put you over the 0.4 mark on the glass in practical terms. It is true that a full UK pint is indeed more. Rest assured that you are as correct as correct can be. I try to bear in mind what might make for a more real world comparison to our (mostly Polish) readers who will most probably walk into an English pub in their respective cities and order a pint of IPA and get a 0.4 Zywiec glass of beer. We made some more detailed description within the text as well.

    Have a fantastic Saint Patrick’s Day.