Does Esperanto use the Double Accusative?

Question

This question is inspired by this precedent: How would you say “I should not have taught you that.”

In German, one can say: Ich lehre dich dies (literal translation into Esperanto: Mi instruas vin tion with two accusative objects). The double accusative is also a construction popular in the Latin language (e.g., Te eam rem doceo.) and in Greek (both classical and modern).

However, most answers to the quoted question use the construction Mi instruas tion al vi using a dative instead of a second accusative.

So my question is:

Is the double accusative used in Esperanto?

Is it a stylistic decision whether to use it or not?

Answer 1

While you will frequently hear the double accusative in spontaneous speech, it is not good Esperanto and should be avoided, especially in writing if you have even a half second to think about what you're saying.

The national languages can sometimes get away with what looks like a double accusative by imposing strict rules about word order.

• I shouldn't have taught you that.
• NOT: I shouldn't have taught that you.

For many verbs, you have some choice about which object you'll express as an accusative and which you'll express with a preposition.

• Mi manĝigas la bebon per kaĉo.
• Mi manĝigas la kaĉon al la bebo.

Answer 2

I think instrui falls into the category of verbs that can have two or more objects with different meanings (the object can either be the thing receiving the teaching, or the subject of the teaching) and sometimes you want to mention both. PMEG has a section about these, but it doesn’t explicitly mention instrui. At the bottom it explicitly says that one can not have multiple objects with different relations to the main verb. So I guess according to PMEG the answer is no, Esperanto does not use the double accusative.

I tried searching in Tekstaro for examples of this anyway, but I only found phrases similar to the following:

Mi vizitis vin en la antaŭa loĝejo por inviti vin kamparon.

Although this has two accusatives, I think this is a different situation because the -n on kamparon does not mark the object (it doesn’t make sense to invite the countryside). Instead, it marks direction and is similar to – but not exactly the same as – al kamparo. PMEG also mentions that this usage is becoming less popular which I think makes sense seeing as it can be a bit confusing.

Answer 3

A double accusative in general can be avoided in Esperanto by inserting an al. Not doing so would introduce an ambiguity for the verb's direct object, accusative, that normally does not exist - by language design.

The relation to the verb:

Mi lernigos vin pri tio.
Mi instruos tion al vi.

Nevertheless there is the form with several accusatives, leaving out je:

Je vendredo mi lernos tion.
Vendredon mi lernos tion.