# Use of "must" and "have to".



## mark89

Hi in this sentence: "I want to cook a chocolate cake. In the fridge there isn't milk, I have to go to buy it" use  "have to"  because without chocolate I don't make  chocolate cake, this is a fact. If instead  I believe that one ingredient of the chocolate cake is chocolate so have to "must". Is it right?


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## The Newt

"I want to cook a chocolate cake. *There's no milk* in the fridge; I have to *go buy* *some*." 

Your question isn't entirely clear, but we wouldn't use "must" in this context,


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## apricots

I would never use must in spoken English. It is just an outdated way of saying have to. 

I must go to the store. 
I have to go to the store. 

You see it in writing to sound more formal or to stress that it is a command. Such as: employees must wash their hands. This is more forceful and formal than employees have to wash their hands.


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## Florentia52

I would use "must" in certain situations in spoken English. "He must be ninety years old," "They've lived by the train tracks for a long time; they must be used to the noise by now," and "She must be wondering where we are" seem reasonable, for example.


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## The Newt

Florentia52 said:


> I would use "must" in certain situations in spoken English. "He must be ninety years old," "They've lived by the train tracks for a long time; they must be used to the noise by now," and "She must be wondering where we are" seem reasonable, for example.



Right, and "he must be on drugs," where "he has to be on drugs" just doesn't have the same punch.


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## suzi br

mark89 said:


> Hi in this sentence: "I want to cook a chocolate cake. In the fridge there isn't milk, I have to go to buy it" use  "have to"  because without chocolate I don't make  chocolate cake, this is a fact. If instead  I believe that one ingredient of the chocolate cake is chocolate so have to "must". Is it right?



No.  What ever you are missing in the ingredients you will need to go out to get.  You use the same construction however "vital" you think the ingredient is! 

I think I say:  "I'll have to go and buy milk."  or "I'll have to go out for milk."


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## Cenzontle

"I want to cook *bake *a chocolate cake."


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## JustKate

Some of my fellow native-speakers are considerably pickier about the use of _must_ than I am. To me, _must_ is more emphatic than _have to_, so I don't use it as often, and I'd generally use it for something more crucial than milk. But if I were really irritated or stressed about having to go buy that milk, I *might* say "I must go get some milk." 

The emphatic form that I use most often, though, is probably "have got to," with the "got" emphasized.


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## apricots

The Newt said:


> Right, and "he must be on drugs," where "he has to be on drugs" just doesn't have the same punch.



This is where I would prefer "he has GOT to be on drugs" or "he's gotta be on drugs."

Now that I think about it though I would use it in the past tense. He must've forgotten about the test. He must've left his keys at home.


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## Dale Texas

Cenzontle said:


> "I want to cook *bake *a chocolate cake."



I was so concentrated on the "must" comments, which was the reason for the post after all,  I hadn't even noticed that. Yes, "bake a cake."


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## mark89

So, when I say: "You must believe in Santa Claus (there isn't proof that Santa Claus exsists)", I could use also "have to". This don't change the mean of  the sentence. Am I right?


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## Cenzontle

There are two kinds of "must".  The technical, linguistic terms for them are "epistemic" and "deontic".
"Epistemic" has to do with evaluating the truth of a proposition, while "deontic" refers to obligation (like "have to").
The epistemic "must" is for drawing conclusions from evidence, as in Florentia52's examples (#4 above).
In "You must believe in Santa Claus" I can see the epistemic "must" if it means "I conclude that you believe in SC because I see you've hung your stocking by the chimney and you've put out some carrots for his reindeer."
But it's the deontic "must" if it means "Santa won't come to your house if you don't believe in him, so you have to believe if you want to see him."
I think many of us use the epistemic "must" ("It must be true"), but would hardly ever use the deontic one ("You must go now"—it sounds dramatic and archaic).


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## Dale Texas

I'm not sure why you added (there isn't proof that Santa Claus exists) which is irrelevant, but yes, both " You must believe/you have to believe are _insistent_: 

"I order you to believe in Santa Claus, you have no other choice" Literally 

In intended meaning though, it's probably a plea, "you've just _got_ to believe..."

Is it possible you meant "Even though there isn't proof that Santa Claus exists, you have to believe in him."


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## se16teddy

I think deontic _must _survives in BE more than in AE (at least as represented in the posts above). But I think it used more where there is an authority figure in control than where circumstances (such as running out of milk) compel us to take a particular action. I found these in the British National Corpus.
_Airdrie and Hearts_ [Scottish football teams]_ must replay on April 14 following their goalless Scottish Cup semi-final draw, and Hearts manager Joe Jordan was the more unhappy manager.
After the pilot's personal safety, the safety of the aircraft must be the next most important consideration; it is always safer to land out than to risk trying to get back with marginal height.
Verbal notification must be confirmed in writing within SEVEN DAYS._


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## mark89

Hi, but believe in one thing and you have  proof that the thing exists there are two things complete different.
So, I ask myself, does this video say right things?

<<Video links must be approved by a moderator *before* being posted (please see rule #4). I am so sorry I had to delete it. -- JustKate, English Only moderator>>


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## mark89

mark89 said:


> Hi, but believe in one thing and you have  proof that the thing exists there are two things complete different.
> So, I ask myself, does this video say right things?
> 
> <<Video links must be approved by a moderator *before* being posted (please see rule #4). I am so sorry I had to delete it. -- JustKate, English Only moderator>>



So the video above says that:
"have to" is used to says something to true (fact)

"You have to drive left side in Britain"

"must" is used to says that you believe that something  is true. Sometimes  when we believe in something we don't need to proof (how I wanted with example to Santa Calus )


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## Florentia52

It is true that we often use "have to" in the case of factual statements. For example, "I _have to_ leave now, or I'll be late for school." But 'I _must_ leave ow, or I'll be late for school" isn't incorrect; it's just a bit formal and old-fashioned.

And we do often use "must" to indicate things we believe without proof: "You're 63 years old? You _must_ be kidding1 You don't look a day over 40!" But we might also say, in that situation, "You _have to be _kidding."

So, if you've seen a video that tries to draw a clear line between the usages, I'm afraid it's oversimplified things.


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## Dale Texas

Florentia52 said:


> It is true that we often use "have to" in the case of factual statements. For example, "I _have to_ leave now, or I'll be late for school." But 'I _must_ leave ow, or I'll be late for school" isn't incorrect; it's just a bit formal and old-fashioned.
> 
> And we do often use "must" to indicate things we believe without proof: "You're 63 years old? You _must_ be kidding1 You don't look a day over 40!" But we might also say, in that situation, "You _have to be _kidding."
> 
> So, if you've seen a video that tries to draw a clear line between the usages, I'm afraid it's oversimplified things.



I agree. I saw the video and cringed when he made such a distinction.


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## Giorgio Spizzi

Frankly, I find all the above thread (an exercise in playing down the importance and frequency of use of modal _must_ in English) an exaggeration—and a misleading one at that. Thank you very much to those who conceded that must may be used epistemically.
Now, how about the following?

Bush must go! (electoral campaign slogan)
Sorry, folks, I must be dashing.
Well I'm 59 if you must know.
Must you go so soon?
And remember you mustn't contact your supervisor until further notice.
I know I mustn't make a mess of it this time.
... and suddenly realized I must call my analyst. (unlike "... and suddenly realized I _had to_ call my analyst ", where a routine is involved).

Would any of the friends upstairs lightheartedly substitute a form of _have (to)_ for _must_ in the utterances above?

GS


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## Florentia52

"Bush must go" works better than 'Bush has to go" in a campaign slogan, because it's shorter. In conversation, "Bush has to go" is more likely.

"I must be dashing" sounds better to me than "I have to be dashing," but only because I imagine that a BE speaker who uses "dashing" (most Ae speakers wouldn't) would be more likely to say "must." As an AE speaker, I could be wrong about that. I would say "I have to go."

'If you must know" is more customary than "if you have to know." It's a bit of a set phrase.

"Do you have to go so soon?" is perfectly normal usage.

In your last two examples, only "mustn't" is correct, because it refers to something that is prohibited or is a bad idea. "You/I don't have to" means something else entirely.


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## apricots

Also, a lot of people would also use need over must. 

I need to go/I have to go/I must go
They need to get this done/They have to get this done/They must get this done


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## mark89

So, in this sentence:
Look! for go to New york, you have to turn left (I have used "have to" because there is the street sign that indicate to us the road, if  there isn't the street sign but I only supposed it (I don't sure, that's my opinion, I had formely to drive this road for New York, but don't remember all it, I suppose that you must  turn left to go to New York) that to go to New York you have to turn left I had to use "must" in the sentence.
But I have understood to your coment that I can use "have to" or "must" whitout change the mean of sentence. To your coment I have understood that "have to" or "must" come also to use to say that "you believe something is true"
Have I understood right?


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## Florentia52

I'm not sure I understand your entire post in #22, but I think you have the right idea.

"To get to New York, you have to turn left here."
"To get to New York, you must turn left here."

These two sentences mean the same thing. It doesn't matter whether there's a road sign, or you know it from memory. We wouldn't normally use the version with "must," but it has the same meaning.

If you think your memory might be faulty, you'd probably say "To get to New York, I think you have to turn left here."


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## mark89

Hi Florentia52, so if I use "must" or "have to" in the my example to say that I am sure that road is that and I don't believe only.
So, I have understood that only differene between "have to" and "must" is that "must" have only present tense. Actually "must" is use in particolar situation instead to "have to"; for example to expression regulation;
example:
People *must* remain seated until the show is over.

Is this true?


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## Andygc

Florentia52 said:


> "I must be dashing" sounds better to me than "I have to be dashing," but only because I imagine that a BE speaker who uses "dashing" (most Ae speakers wouldn't) would be more likely to say "must."


"be dashing". Does anybody say that? . I imagine that a BE speaker would say "I must dash", rather than "I have to dash". I would. 
However, "I have to be going" and "I must be going" seem to me to mean the same, and I'd happily accept and expect either.



mark89 said:


> for example to expression regulation;
> example:
> People *must* remain seated until the show is over.


Yes, that's something that needs "must".


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## mark89

Hi, so, If I have understood well,  in the sentence "I have to lay out my room" the modal verb "have to" express opinion or obligation in base to contex; for example, if my mother tell me to lay out my room, "have to" express obligation. Instead "have to" express an opinion if I lay out my room because have invited a girl (I have to present myself well to first appointment. I think that it is right thing to do). But Might I use "must" to express obligation?


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## RJT98

Either 'have to' or 'must' can be used to express obligation in this case, though I personally would go for 'have to' in a conversation with someone.


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## mark89

Hi RJT98, so it dependes to contex if we use "have to",  to express obligation or opinion.


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## Hermione Golightly

Yes the form used depends on what the speaker knows about the situation.
This is not always explicit.
If I use must 'I must tidy the living room' there's probably some external reason for me feeling obliged, perhaps we have guests coming and I don't want them to think we live in a mess.
Of course, if I want to talk about future obligations using 'will', I have to use 'have to' because there's no future form of 'must'.
'My parents are visiting next Tuesday so I'll have to tidy up at the weekend'

I find it extremely difficult to estimate how much I use either of the two forms when there is an option because my choice either doesn't really matter or I subconsciously choose whichever suits my situation better.
The learner's best bet is to study the various functions of the forms which represent an attempt to simplify things, as well as the actual rules determining their use.
And please don't ever start saying 'gotta' instead of 'got to'.


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## mark89

Hi Hermione, so "must" is used to expresses opinion, but also to expresses obligation.


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## JustKate

"Must" and "have to" can both be used to express an opinion, an obligation or a strong intention. (So can "have got to," although it may be used less often for obligations than the other two are.) Which is intended really depends on context.


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## mark89

So, in the sentence: "I have to arrive to work early, because my boss in very strict" I might also use must. Is it right?


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## Rhye

Yes, that is correct. As was discussed earlier, most people don't use "must" in that sense very often, but it is perfectly correct, and understandable, if you do.


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## mark89

Hi Rhye, so "have to" and "must" may express both obligation or opinion. I understand that a sentence express obligation or opinion  to contex;
example:

" I have to/ must run two times on day" rapresents an obligation if my coach have said to me to do. Or the sentence rapresents an opinion if I think that run two time on day is good for me.


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## Rhye

Yes, that's correct, the obligation could be one that someone else set for you or one that you yourself set (if you set it for yourself it's sometimes a looser obligation); both "must"/"have to" work in either case.


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## mark89

Hi Rhye, so the sentence "your father is very ill you must visit him right away" express a personal blief. But I_ can use also "have to" instead to "must" to express a personal belief.

the sentence "you have to dry on the left side in Britain"  express something to true in general and  it don't only for my self (it is right thing to do. It is a rule), But I can use also "must"; is it right?

the sentence "there is a tempest. the captain say that we have to continue to go forward" (maybe it isn't right thing to do. May be dangerous go  forward. It is a order to captain). But i can use also "must". Have I said well?

_


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## Rhye

Yes, in either of these cases you could use "must" or "have to". However, I hope in that first sentence you meant "you have to _drive_ on the left side in Britain". Admittedly, it does rain a lot in Britain, but I don't think it matters which side of the road you *dry* on.


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## Imladris

As far as I know, internal obligation (must) versus external obligation (have to) distinction does not apply to American English, and I am not so sure whether it does so to British English. Rymond Murphy makes such a distinction in his well-known "English Grammar in Use" but then it is for non-native speakers. Epistemic use of "must" is quite irrelevant here as the subject at hand is about the "deontic" use.

It would be more enlightening to learn from our native speaker friends where these two "must, have to" cannot be interchangeable in deontic use.


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## bennymix

I agree with Kate.  'must' hasn't gone from my speech, and I can conceive using it in the cake example.
"The cake is for 7pm tonight and there's no chocolate in the house, so I must go, right now, and buy some!"

I applaud Kate's keeping the standards with "I have got to", but with deep shame I confess,
"I gotta go to the store" might slip out of my mouth.



JustKate said:


> Some of my fellow native-speakers are considerably pickier about the use of _must_ than I am. To me, _must_ is more emphatic than _have to_, so I don't use it as often, and I'd generally use it for something more crucial than milk. But if I were really irritated or stressed about having to go buy that milk, I *might* say "I must go get some milk."
> 
> The emphatic form that I use most often, though, is probably "have got to," with the "got" emphasized.


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## mark89

Hi  to all. Yes Rhye, I meant "you have to _drive_ on the left side in Britain""
so I can use "have to"  or "must", in a sentence, to express a positive obligation, without change the meaning to the sentence.
So in deontic use "must" and "have to" cannot be interchangeable. Is this true to american native speaker and britain native speaker?
example:
"to boil the wather you have to set the oven on 100 C" ("have to" is used in deontic modality in above sentence. Am I right?)


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## se16teddy

1. You have to drive on the left in Britain.
2. You must drive on the left in Britain.
I think there is a nuance here for me. 1. Is thinking about the rules that apply the pressure on the driver, like in #1 _have to _is thinking of the contents of the fridge. 2. Is thinking more of the psychological impact - the rules create a moral obligation on the driver, or the driver is thinking about what action to take to avoid punishment.


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## Kirill V.

Hi, everybody!

I meant to provide a useful link on the use of modal verbs, but then realized that once you click on it it starts to upload approx. 200 Gb on your computer and crushes the system.


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