1.4.1 shall and must
One of the most interesting topic within the modal verbs are the verbs shall and must. Shall and must seem to be quite simple and easy as long as you do not think too much about it. There is the issue of being polite or rude and then there is the common use of shall as a future form etc. The point here is it's better to understand the differences before we can explain how they are used in Spanish. Therefore, we start to think a little bit about the English use of shall and must. What does it actually mean and when these modal verbs are used?
In general, one could say that the use is in quite a similar way, but we'll go all the way step by step.
shall and must
deber= shall
tener que = to have to, must
tener que = to have to, must
1.4.2 Tener que and have to with very limited freedom of choice
After all this discussion we can keep one thing for a fact that tener que is used like to have to and this is the case when there is no or very limited freedom of choice, no room for manoeuvre or the logical consequence does not leave another alternative.
Example:
The tank was empty therefore we had to leave the car there.
correct: El tanque estaba vacío, asi que tuvimos que dejar el coche ahí.
incorrect: El tanque estaba vacío, asi que debiamos dejar el coche ahi.
correct: El tanque estaba vacío, asi que tuvimos que dejar el coche ahí.
incorrect: El tanque estaba vacío, asi que debiamos dejar el coche ahi.
Example:
There was no other solution, he had to do it.
correct: No había otra solución, tenía que hacerlo.
incorrect: No había otra solución, debía hacerlo.
correct: No había otra solución, tenía que hacerlo.
incorrect: No había otra solución, debía hacerlo.
Example:
He was so drunk that he had to vomit.
correct: Estaba tan borracho, que tuvo que vomitar.
incorrect: Estaba tan borracho, que debío vomitar.
correct: Estaba tan borracho, que tuvo que vomitar.
incorrect: Estaba tan borracho, que debío vomitar.
Example:
The detonation was so loud that all had to cover their ears.
correct: La detonación fue tan fuerte, que todos tuvieron que taparse los oídos.
incorrect: La detonación fue tan fuerte, que todos debían taparse los oídos.
correct: La detonación fue tan fuerte, que todos tuvieron que taparse los oídos.
incorrect: La detonación fue tan fuerte, que todos debían taparse los oídos.
Example:
The carburettor was wet therefore we had to wait until it dried.
correct: El carburador se había mojado, así que tuvimos que esperar a que se secara.
incorrect: El carburador se había mojado, así debimos esperar a que se secara.
correct: El carburador se había mojado, así que tuvimos que esperar a que se secara.
incorrect: El carburador se había mojado, así debimos esperar a que se secara.
1.4.3 shall and have to in negative clauses
The best known negative clauses with shall are the ten commandments of the bible.
The 10 commandments
I You shall have no other gods but me.
II You shall not make unto you any graven images.
III You shall not take the name of the Lord your God in vain.
IV You shall remember the Sabbath and keep it Holy.
V You shall honour your mother and father.
VI You shall not murder.
VII You shall not commit adultery.
VIII You shall not steal.
IX You shall not bear false witness.
X You shall not covet anything that belongs to your neighbour.
II You shall not make unto you any graven images.
III You shall not take the name of the Lord your God in vain.
IV You shall remember the Sabbath and keep it Holy.
V You shall honour your mother and father.
VI You shall not murder.
VII You shall not commit adultery.
VIII You shall not steal.
IX You shall not bear false witness.
X You shall not covet anything that belongs to your neighbour.
It is quite clear somebody who has the power to do so demands something. When substituting shall with must the meaning is not altered but rather emphasised.
The 10 commandments
I You must have no other gods but me.
II You must not make unto you any graven images.
III You must not take the name of the Lord your God in vain.
IV You must remember the Sabbath and keep it Holy.
V You must honour your mother and father.
VI You must not murder.
VII You must not commit adultery.
VIII You must not steal.
IX You must not bear false witness.
X You must not covet anything that belongs to your neighbour.
II You must not make unto you any graven images.
III You must not take the name of the Lord your God in vain.
IV You must remember the Sabbath and keep it Holy.
V You must honour your mother and father.
VI You must not murder.
VII You must not commit adultery.
VIII You must not steal.
IX You must not bear false witness.
X You must not covet anything that belongs to your neighbour.
The meaning changes drastically when substituting shall / must with to have to.
The 10 commandments
I You have to have no other gods but me.
II You do not have to not make unto you any graven images.
III You do not have to not take the name of the Lord your God in vain.
IV You have to remember the Sabbath and keep it Holy.
V You have to honour your mother and father.
VI You do not have to not murder.
VII You do not have to not commit adultery.
VIII You do not have to not steal.
IX You do not have to not bear false witness.
X You do not have to not covet anything that belongs to your neighbour.
II You do not have to not make unto you any graven images.
III You do not have to not take the name of the Lord your God in vain.
IV You have to remember the Sabbath and keep it Holy.
V You have to honour your mother and father.
VI You do not have to not murder.
VII You do not have to not commit adultery.
VIII You do not have to not steal.
IX You do not have to not bear false witness.
X You do not have to not covet anything that belongs to your neighbour.
Suddenly we have all the freedom in the world, which is the not-intended result of a linguistic experiment. However, every single one thinks about the wide possibilities given this way of thinking the author rather turns back to Spanish than to the philosophic implications of language technicalities.
Point here shall be that in also Spanish negative clauses deber (shall) can't be substituted with tener que (to have to). Since there is no other word than tener que for must the question about this is rather obsolete.
The ten commandmends can be found in Spanish in three different versions
Using the future
No tendrás dioses ajenos delante de mí.
= You will not have other gods but me.
No tomarás el nombre de Jehová tu Dios en vano.
= You will not take the name of the Lord your God in vain.
Honra á tu padre y á tu madre.
= You will honour your mother and father.
No cometerás adulterio.
= You will not commit adultery
No hurtarás.
= You will not steal.
No hablarás contra tu prójimo falso testimonio.
= You will not bear false witness.
= You will not have other gods but me.
No tomarás el nombre de Jehová tu Dios en vano.
= You will not take the name of the Lord your God in vain.
Honra á tu padre y á tu madre.
= You will honour your mother and father.
No cometerás adulterio.
= You will not commit adultery
No hurtarás.
= You will not steal.
No hablarás contra tu prójimo falso testimonio.
= You will not bear false witness.
Using the imperative
No mates. = Do not murder.
No cometas adulterio. = Do not commit adultery.
No robes. = Do not steal.
Honra a tu padre y a tu madre. = Honour your father and mother.
No cometas adulterio. = Do not commit adultery.
No robes. = Do not steal.
Honra a tu padre y a tu madre. = Honour your father and mother.
With deber
No debes matar. = You shall not murder.
No debes cometer adulterio. = You shall not commit adultery.
No debes levantar falso Testimonio. = You shall not bear false witness.
No debes cometer adulterio. = You shall not commit adultery.
No debes levantar falso Testimonio. = You shall not bear false witness.
Even though the translation into English in future-form and imperative is possible and sounds plausible, it would probably mostly be translated with shall.
We have the same picture in the Spanish logic. The verb deber can't be substituted with tener que because the meaning would be altered.
Example
No debes fumar tanto.
= you should not smoke so much.
No tienes que fumar tanto.
= You do not have to smoke so much.
= you should not smoke so much.
No tienes que fumar tanto.
= You do not have to smoke so much.
Example
Yo pienso que no debes ser tan avaricioso.
= You shouldn't be so mean.
Yo pienso que no tienes que ser tan avaricioso (,para ahorrar dinero).
= You do not have to be so mean.
= You shouldn't be so mean.
Yo pienso que no tienes que ser tan avaricioso (,para ahorrar dinero).
= You do not have to be so mean.
Example
No debes ser tan curioso.
= You shouldn't be so curious.
No tienes que ser tan curioso(,para saber lo que pasó).
= You do not have to be so curious.
= You shouldn't be so curious.
No tienes que ser tan curioso(,para saber lo que pasó).
= You do not have to be so curious.
El ensayo no tiene que ser tan corto que parezca una meditación, ni tan largo que se asemeje a un tratado.
= The essay doesn't have to be so short that it is similar to a meditation, but also not that long that it seems to be a contract.
El ensayo no debe ser tan corto que parezca una meditación, ni tan largo que se asemeje a un tratado.
= The essay should not be so be so short that it is similar to a meditation, but also not that long that it seems to be a contract.
Un hombre no debe llorar
= A man shall not cry. (meaning: It's not good if he does.)
Un hombre no tiene que llorar.
= A man doesn't have to cry. (meaning: There is no one demanding it or setting an obligation to do so.)
= The essay doesn't have to be so short that it is similar to a meditation, but also not that long that it seems to be a contract.
El ensayo no debe ser tan corto que parezca una meditación, ni tan largo que se asemeje a un tratado.
= The essay should not be so be so short that it is similar to a meditation, but also not that long that it seems to be a contract.
Un hombre no debe llorar
= A man shall not cry. (meaning: It's not good if he does.)
Un hombre no tiene que llorar.
= A man doesn't have to cry. (meaning: There is no one demanding it or setting an obligation to do so.)