Must & have to

Question

Please coud you tell me:

Do the negatives of tengo que + infinitive / hay que + infinitive and ****deber + infinitive** mean "I must not ..." or " I don't have to" which are of course almost opposites. Is "hay que ...." the same?

eg I don't have to go to school today / I mustn't go to school today

I ask as a fluent French speaker where the equivalent (il ne faut pas) could mean either according to the context.

No dictionary seems to quote negative examples of this idiom.

Excellent question. I await some good responses. - gringojrf, Nov 25, 2015

Great question and great responses , we have been lacking these type of discussions of late. - ray76, Nov 26, 2015

Answer 1

Welcome to the forum. Can you add your language level in Spanish and English to your profile? It helps anyone answering your question or reading your replies. For example if your Spanish is at a good level a native Spanish speaker may answer in Spanish.

It is an interesting question which I hadn't given proper thought to.

Here is a partial answer in word reference when a Spaniard asked about the English terms.

word reference

I look forward to the answers.

:) - ian-hill, Nov 25, 2015

Answer 2

I was taught that "must" has to do with an internal obligation, meaning that it's the speaker who wants to do the action. While "have to" has to do with an external obligation, someone else is telling you to do the action.

I must visit my grandmom because she's ill. (Because I want to do so, I feel like it's an obligation.)

I have to visit my grandmom. (Because my father told me to do so.)

Must not = obligation not to do something

Don't have to = absence of obligation

To be honest I don't know if this is accurate, it's what I was taught in school. So if this is incorrect, please do tell me!

I would translate "tener que" as "have to".

Tengo que limpiar mi habitación. I have to tidy up my room.

Hay que could be translated as "must" I guess, or as "need to".

Si se quiere mejorar, hay que practicar. If you want to improve you must practice. / If you want to improve you need to practice.

Don't take my word for it though, modal verbs are confusing and grammar is obnoxious...!

Feel free to correct me.

For me, "I have to" fills both situations. I never use the word "must" in conversation - HackerKing, Nov 26, 2015

I must say that I like your answer , but am not obligated to do so , it is entirely my prerogative. - ray76, Nov 26, 2015

I agree 'must' may indicate personal obligation or desire and 'have to' may indicate an obligation or desire from an external source. I must phone you later ( because I want to) I have to phone him later (because he wants me to), - AndyTFS, Nov 26, 2015

Answer 3

This question has been on my mind all day. In the affirmative in English, as I know it, must is an slightly archiac/formal word used by my mom.

You must clean your room. You have to clean you room. To me, no difference.

You must brush your teeth to avoid the dentist. You have to brush your teeth to avoid the dentist. To me, no difference.

You must obey the law. You have to obey the law. To me, no difference.

You must complete this form. You have to complete this form. To me, no difference

"Must" may be more formal but conveys exactly the same sentiment and level of obligation.

Now in the negative that all changes as addressed by others above.

You must not leave this room. You do not have to leave this room. These are two very different statements.

You must not leave this room. You have to stay in this room. Two ways of saying the same thing using opposite verbs; leave and stay.

Still waiting for a good Spanish explanation.

You must not leave this room. You have to stay in this room. -- These are N O T the same thing. - ian-hill, Nov 26, 2015

Besides the obvious one in negative and the other in affirmative, I don't see the diff, Same thing with You can't leave this room. - chileno, Nov 26, 2015

Or "it is prohibited to leave this room", for that matter. - chileno, Nov 26, 2015

You must not leave this room.. Suggests there will be consequences if you do whereas you have to stay in this room could be an offer. You have to stay in this room if you want to wait because all of the other rooms are occupied. - AndyTFS, Nov 26, 2015

Answer 4

In English this is how I see it.

I must leave this burning building - (it is good for me to do so)

Mustn't is a prohibition.

Debo dejar este edificio en llamas.

I have to do my homework. - (I have an obligation to my teacher to do so)

I don't have to = I have no obligation.

Tengo que hacer mis tareas.

But, You must leave the building at once, ir an order, or a strong suggestion? Yes? - annierats, Nov 25, 2015

But - not an obligation. - ian-hill, Nov 25, 2015

Answer 5

Ian:

So, in English "have to" is an obligation while "must" or "should" are not?

You sure?

To me, must and have are obligations while should is not but it is a recommendation.

I should is an obligation but only if certain conditions are met . - ray76, Nov 26, 2015

Correct, as it is in Spanish. - chileno, Nov 26, 2015

Answer 6

Examples of the type of context these occur in, I have no rules to hand out.

No debes comer patas fritas si estás tratando de perder peso. ( You should not/ you ought not eat fried potatoes if you're trying to loose weight. ) Advice.

Hay que comer patatas fritas si no haya otra comida en casa. ( You have to eat fried potatoes if there is no other food in the house). An impersonal sort of statement.

Tienes que comer las patatas fritas tan horribles de la abuela, sin quejarte porque la abuela no te perdonara nunca si no las comerías ( You must/ you have to eat the horrible fried potatoes that Granny makes because Granny would never forgive you if you didn't eat them .) A personal strong suggestion.

Corections much appreciated. - annierats, Nov 25, 2015