[This reference](https://www.reddit.com/r/learnspanish/wiki/index/faq/#wiki_.2022_omission_of_complements) describes some nuances of meaning when complements are omitted.
It seems to also imply some rules about when complements can be omitted, but I’m not totally clear on that. **So I’m looking for any general advice you can give me about when complements can be omitted.**
The above reference gives the following example:
>Le dieron el premio. / **A ella** le dieron el premio.
Based on the above reference, analogies to similar cases covered in the RAE, and on some interactions online, I have **guessed** the following rules. **Are these approximately correct?**
1. Almost always, in a sentence like the above when the complement has the structure “a [phrase describing a person or living thing]” and a corresponding pronoun is also present (“le” in this case, the complement may be omitted. This is grammatically correct but, depending on the situation, may be confusing or odd-sounding.
2. Often, in a sentence like the above, but when the complement has the structure “a [phrase **NOT** describing a person or living thing],” even if a corresponding pronoun is also present, it is not a good idea to omit the complement. At best this is confusing and people will assume that the corresponding pronoun refers to a person; at worst, this is ungrammatical. For example, I have been told that “Le envié una carta” **cannot** be used to mean “I sent a letter to it” if “it” refers to the city of Paris.
3. However, there are exceptions to #2. For example, I think that [this answer on StackExchange](https://spanish.stackexchange.com/questions/41414/a-los-problemas-del-mundo-no-les-doy-mucha-importancia-no-les-doy-mucha-i/41422#41422) is saying that the following sentence is allowed: “No les doy mucha importancia.”, where “les” refers to “A los problemas del mundo.”
**(There are all kinds of reasons why my inferences could be wrong.** In particular, #2 presupposes that I am correctly identifying what counts as a complement. For example, I think that “a París” represents an indirect complement in the sentence “Envié una carta a París.”, because “París” seems like the recipient of the letter. But I could be wrong; maybe the phrase “a París” is serving some other similar grammatical function.)
You’re looking at it the wrong way. It’s not when to *omit* it that matters, but when to make it *explicit*. And you only make it explicit when you want to emphasise whom you’re referring to.
It’s the difference between “I’m talking to you (it’s not the radio you’re hearing)” and “I’m talking to *YOU* (not to someone else)”.
On the other hand, “a París” is not an Indirect Object, it’s a *Complemento Circunstancial de Lugar*. You don’t reduce it to “I sent a letter to it” (*Le envié una carta*), but “I sent a letter there” (*Envié una carta allí*).
You’re taking about indirect objects and , specifically, indirect object reduplication. The subreddit’s wiki has an explanation, and I’m sure SpanishDict has articles on it too.
I’m back again!
1. Yes, this is just disambiguation, as you know that “le” can refer to él or ella. However, and importantly, “Le” as an indirect object pronoun doesn’t have to be a person. Think of “The government provided financial support to the failing bank”. No people in this sentence, and the indirect object pronoun is a failing bank. There are lots of machines that do automatic things with an object and a non-human recipient. “The computer stores the quarterly reports on the private internet”.
2. By default, Spanish (and English) speakers consider the indirect object to be a person because this is almost always the case in our daily interactions. Common ditransitive verbs like give, receive etc. are said so frequently we get the impression that the IO is ***always*** a person, but it isn’t true. The different between Spanish and English is that the IO can be “him,her,**it,**them” in English, but Spanish only has “him or her” or “them” and no “neutral” gender that separates humans from things, hence increasing ambiguity (its not clear in words if a pronoun on its own is referring to a person or a thing, so in Spanish you have to disambiguate if the context doesn’t make it clear). So, yes, IOPs very often have to be disambiguated, and especially so in Spanish (Spanish pronouns themselves cannot distinguish whether the object is animate or not, as there is no “it”).
Regarding “I sent a letter to Paris”. What question extracts “to Paris” from this sentence? It would be “Where did you sent the letter”. This question reveals that “To Paris” is not an object complement. Its another prepopsition + noun, in other words, that nasty prepositional complement, so “le” cannot refer to it. “Le” refers to the person (in Paris) to whom you sent the letter. In this case, since you haven’t said who you are sending the card to, “le” should be omitted (because you don’t want to turn “to Paris” into a person).
Perhaps what translates your intention is “envié una carta a París”, without “le”, so the sentence is impersonal, and the listener understands that you are not actually expecting Paris to read your letter, or that Paris is the person’s name. Alternatively you could explicitly state the person: “Le envié una carta a mi amigo, quién vive en París”. That would be much less ambiguous.
A: Me agobian los problemas del mundo. No creo que podamos solucionarlos todos.
B: Pues, yo no les doy mucha importancia (…)
B doesn’t need to repeat the complement. This is called ***ellipsis***, and happens in all languages. Frequently teachers and linguists use (…) to mark ellipsis if they need to highlight it. The ellipsis here is the omitted “a los problemas del mundo”. In this particular case, the ellipsis can start the sentence too, but most importantly, its a waste of breath repeating it.
Context is everything. You only have to state a complement if it is ***unclear*** from the context of the conversation (or something you are writing) what a pronoun refers to. In real life, this doesn’t happen much because you have to state something *before* it can be referred to with a pronoun.
This, of course, with the exception of the “redundant indirect object”, that is used even when the complement is there in conversational Spanish (it is often omitted in formal language if there is no ambiguity).