While living in Mexico, I once heard the following expression: “Se te ha de figurar”. All of my grammatical knowledge was insufficient to decipher its meaning and I wrote it down immediately, hoping that the internet might resolve my confusion. It was then that I discovered a construction which has since cropped up dozens of times in conversation: haber de + verbo. Before explaining its meaning to you, I offer the following examples:
- Ella ha de llegar mañana.
- Él ha de tener veinte años.
- He de haber dejado mis llaves en la oficina.
- Ha de haber sido interestante conocer al presidente en persona.
- Ha de haber sido difícil hablar con tu jefe.
It turns out that, haber de + verbo is a common colloquial construction for “must” or “ought to be”. It’s a way of expressing conjecture with respect to things that may have happened, are happening or may yet occur. Thus, the preceding examples translate as follows:
- She must/should be arriving tomorrow.
- He must be 20 years old.
- I must have left my keys at the office.
- It must have been interesting to meet the president in person.
- It must have been difficult to speak with your boss.
The example in the first paragraph “Se te ha de figurar” means “You must be imagining it”. I had never before come across this form in any textbook, but was familiar with deber de + verbo as a means of expressing conjecture with “must be” statements. And, as it happens, each of the foregoing sentences can be translated as follows:
- Ella debe de llegar mañana = She must be arriving tomorrow.
- Él debe de tener veinte años = He must be 20 years old.
- Debo de haber dejado mis llaves en la oficina. = I must have left my keys at the office.
- Debe de haber sido interesante conocer al presidente en persona. = It must have been interesting to meet the president in person.
- Debe de haber sido difícil hablar con tu jefe. = It must have been difficult to speak with your boss.
There is a little confusion, even in English, with the terms and corresponding translations of “must”, “should” and “ought to”. Sometimes we use these to express conjecture, as in all the examples above, but often we refer to obligation. The following examples in English illustrate what I mean:
- He must arrive by 10 PM.
- He must be around 45 years of age.
The first example expresses an obligation imposed upon the subject, whereas the second is simply a supposition. Both haber de and deber can expresses both concepts, but there is a slight shade of difference with respect to the latter. Note these examples:
- Si no quiere que lo corran, ha de llegar a tiempo = Si no quiere que lo corran, debe llegar a tiempo = If he doesn’t want to get fired, he must arrive on time.
With haber de + verbo, there is no change in the construction. There is only a change in the context. Notice, however, that with deber the preposition “de” has disappeared. If we added it back, the sentence would translate “He must be arriving on time” as a matter of conjecture. Here’s the catch: native speakers don’t always follow the rules and you will hear all of the constructions described above, plus sentences like “Debe tener veinte años” in which the preposition has disappeared but the meaning is obviously one of conjecture and not of obligation. It may seem annoying that Spanish uses the same verbs to express different concepts, but we pretty much do the same in English.
In any event, you now have two extremely common ways of expressing both conjecture and obligation. The next time someone says “Has de estar muy cansado” or “Debes (de) estar muy cansado”, you’ll know what is meant 🙂