Have to and must.

I read somewhere that "have to" is not a modal verb and so is not subjective, as must is. Is that correct? Is that why there is no subjectivity in things such as "I have to leave right now"?

Have to is used in the present tense to indicate that the obligation does not originate with the speaker. Must is used to indicate the contrary, or simply to indicate a very strong obligation. Since must has no past or future form, have to is always used for tenses other than the present tense.

You're overcomplicating your life here:

1. You are correct, "have [to]" is not a modal verb.

2. "Have [to]" means about the same thing as "must."

That's it.

JJM hit the nail on the head with this one; I agree.

In some languages the distinction between "must" and "have to" doesn't exist at all e.g. in Romanian, Trebuie sã plec (tray-boo-yay suh plek) can mean either "I have to go" or "I must go."

I don't think any Romance language makes the distinction between "have to" and "must"

It: Dovere
Sp & Pt: Deber
Fr: Devoir

Fr: Devoir and Falloir

<<I don't think any Romance language makes the distinction between "have to" and "must">>

Actually, Spanish "tener que" effectively translates pretty much one-to-one with English "have to" while "deber" is stronger; meaning "must." English obligational "should" (which is usually not as strong as "must" in meaning) is expressed by the conditional forms of "deber" in Spanish. Thus:

"mañana tengo que ir al centro" = Tomorrow I have to go downtown.

"Debes hacer toda tu tarea antes de jugar" = "You must do all your homework before playing"

"A lo mejor debería limpiar el auto hoy" = I should probably clean the car today.

So much for studying Spanish for all those years. I must be relating it to Italian in which "have to" and "must" are expressed with the same verb. Is the French "falloir" of different strength than "devoir"? If it is, then that would make Italian and Romanian stand differently in this respect from French, Spanish and Portuguese. At any rate, I wonder how this distinction came up. Germanic influence (seeing as the distinction is part of English too)?

At least here, "have to" is simply the normal form for expressing obligation or necessity, and is quasimodal in nature in that it fits the functionality of a modal verb, but does not follow the same grammatical rules as modal verbs proper in English. On the other hand, the modal verb "must" is strongly emphatic in nature, and is not used for most purposes in practice. And I must myself reiterate that "have to" is used for expressing the past and future here, as "must" cannot express such here, as it has no form directly equivalent to, say, German "musste" and "müsste" and cannot be used with another modal or auxiliary, unlike how German "müssen" can used together with "werden" (equivalent here to English "will").

Fr <il faut qu'elle> / <il lui faut> ~ En <she must> / <she has to> / <she needs to>
Fr <il a fallu qu'elle> / <il lui a fallu> ~ En <she had to> / <she needed to>
Fr <il faudra qu'elle> / <il lui faudra> / <il va falloir qu'elle> ~ En <she will have to> / <she will need to>

Fr <elle est obligée de> / <il va falloir qu'elle> ~ En <she has to> / <she needs to>
Fr <elle a été obligée de> ~ En <she had to> / <she needed to>
Fr <elle sera obligée de > / <il va falloir qu'elle> ~ En <she will have to> / <she will need to>

Fr <elle doit> ~ En <she must> / <she has to>
Fr <elle a dû> ~ En <she had to>
Fr <elle devra> ~ En <she will have to>

Fr <elle a à> ~ En <she has to> / <she needs to>
Fr <elle a eu à> ~ En <she had to> / <she needed to>
Fr <elle aura à> ~ En <she will have to> / <she will need to>

Fr <elle est tenue de> ~ En <she must> / <she has to>
Fr <elle a été tenue de> ~ En <she had to>
Fr <elle sera tenue de> ~ En <she will have to>

Tiffany,

There are equivalent verb forms in Spanish for both "have to" and "must."

"Tener que" = have to
"Deber" = must

Examples:

Tengo que ir al trabajo, dejé mi billetera ahí. = I have to go to work, I left my wallet there.

Debes ir a la escuela. = You must go to School.

I study Italian as well, but I haven't found two different verbs to equal these.

Kirk,

In Spanish, we usually equal the form "deber de" to "should" as well. This might not apply to all Spanish speaking countries.

Example:

¿Quieres ganar el examen? Entonces deberías de estudiar.
Do you want to pass the exam? Then you should study.

César,
Nope, in Italian there is only one verb: dovere.

Greg,
Falloir e devoir significano le stesse cose, sì?

Tiffany : « Falloir e devoir significano le stesse cose, sì? »

Quasi le stesse cose !

Fr <devoir> ~ It <dovere>
Fr <falloir> (dérivé de <faillir>) ~ It <essere necessario> / <dovere> / <occórrere>.

La <debere> — La <fallere> / <fallire>

Toutes les précisions sur <devoir> [d2vwaR] : http://www.orbilat.com/Languages/French/Grammar/Verbs/devoir.htm .

Sur <faillir> [fajiR] : http://www.orbilat.com/Languages/French/Grammar/Verbs/faillir.htm .

Sur <falloir> [falwaR] : http://www.orbilat.com/Languages/French/Grammar/Verbs/falloir.htm .

<<In Spanish, we usually equal the form "deber de" to "should" as well. This might not apply to all Spanish speaking countries. >>

Yes, I've heard that form used by some speakers, but it wasn't one I heard while living in Argentina. I sometimes hear it used by Mexican speakers.