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.
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’
Trigger Warning: A lot of what course books have been writing about this topic is outdated hogwash!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