how to be definite in Estonian

[chung]

Thanks to Finnish I've been reexamining internally how languages express concepts that are taken for granted in Romance or Germanic languages (if at all). Examples include grammatical gender, prepositions that do not always govern a case other than nominative, and Wackernagel's law.

In particular, I've been thinking about (in)definiteness and how often I see things being framed initially by mentioning definite articles (or lack thereof). I know that in Finnish, one can express definiteness in ways that are alien to someone familiar only with FIGS (French, Italian, German, Spanish) or English.

One technique is word order.

Tietokone on pöydällä. "The computer is on a/the table."
Pöydällä on tietokone. "There is a computer on a/the table."

Another is to use a different case (sometimes in conjunction with word order)

Tietokone ei ole pöydällä. "The computer is not on a/the table."
Pöydällä ei ole tietokonetta. "There is no computer on a/the table."

Ostin kirjat. "I bought the books." (i.e. books that I had referred to previously or a specific group of them which you the listener (probably) know about.)
Ostin kirjoja. "I bought some books." (i.e. books that I had not referred to previously or just some assortment which you the listener (probably) didn't know about).

Opin englantia. "I learned [some] English." (I'm not quite saying that I've mastered it or that the process was thorough or complete)
Opin englannin kielen. "I learned the English language." (thorough process completed with an insinuation of mastery)

Yet another way is to use a demonstrative pronoun.

Kaksi lasta leikkii puistossa. "Two children are playing in the park."
Nämä kaksi lasta leikkivät puistossa. "These two children are playing in the park."

How is (in)definiteness expressed in Estonian?

[ainurakne]

Pretty much the same way as in your Finnish examples.

Tietokone on pöydällä. "The computer is on a/the table."
Pöydällä on tietokone. "There is a computer on a/the table."

Arvuti on laual. "The computer is on a/the table."
Laual on arvuti. "There is a computer on a/the table."

Tietokone ei ole pöydällä. "The computer is not on a/the table."
Pöydällä ei ole tietokonetta. "There is no computer on a/the table."

Arvuti ei ole laual. "The computer is not on a/the table."
Arvutit ei ole laual. or Laual ei ole arvutit. depending on what exactly you want to emphasize - "There is no computer on a/the table."

Ostin kirjat. "I bought the books." (i.e. books that I had referred to previously or a specific group of them which you the listener (probably) know about.)
Ostin kirjoja. "I bought some books." (i.e. books that I had not referred to previously or just some assortment which you the listener (probably) didn't know about).

Ostsin raamatud. <- now here, in my opinion, using accusative refers more to an action with a definitive result (finished action). Differently from Finnish, Estonian often allows or requires some additional words when using finished action - in this case "ära" can be added: Ostsin raamatud ära.
On the other hand, definitive result in turn means that you are speaking about a specific set of books - but that doesn't necessarily mean that the listener already knows about them.
In Estonian, the definiteness or indefiniteness is not that important most of the time.

Ostsin raamatuid. <- again, using partitive here refers mostly to unfinished action - in a sense that in this context it is not important whether this action has had definitive results or not: "I did some book shopping". But that in turn also makes the set of books unspecified (at least in this context), and this is why you can also speak about "some" books here.
On the other hand, if you add a recipient to this sentence: Ostsin omale raamatuid. (I bought myself [some] books) - the action becomes more definite and the emphasis shifts more to indefinite books. In my opinion the above sentence is quite similar in meaning to: Ostsin omale mõned raamatud. (I bought myself some books).

Opin englantia. "I learned [some] English." (I'm not quite saying that I've mastered it or that the process was thorough or complete)
Opin englannin kielen. "I learned the English language." (thorough process completed with an insinuation of mastery)

Õppisin inglise keelt. "I did some English learning." (whether it had any definitive results is irrelevant in this context)
Õppisin inglise keele selgeks. "I mastered the English language."
In this case, using accusative definitely requires an additional word. One possibility is "selgeks" (translative of "selge" - clear), another one is "ära": Õppisin inglise keele ära. (but when using "ära", "inglise keel" doesn't necessarily have to mean the language itself, it can also mean the subject in school for example - so in that specific context it can also mean "I finished my English homework.")

Kaksi lasta leikkii puistossa. "Two children are playing in the park."
Nämä kaksi lasta leikkivät puistossa. "These two children are playing in the park."

Kaks last mängivad pargis. and Need kaks last mängivad pargis.
In this case I would usually use demonstrative pronoun only if I also point my finger to those kids or show the listener the pictures or names of those kids (i.e. I connect the persons and their credentials).
If the kids have already been mentioned then I would use the personal pronoun "nemad/nad" or refer to them as "lapsed".

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Indeed, using partitive case can in some contexts mean that you are talking about some unspecified or some unknown amount of things and using accusative, that you are talking about specified or some known amount of things, but mostly partitive vs. accusative differentiates between the process and the "achievement".
For example: "Ostsin auto." (accusative) vs. "Ostsin autot." (partitive)
In the first sentence you emphasize that you now have a car (even if the listener doesn't know what car you are talking about)
In the second sentence you focus on the process of buying (and it's irrelevant whether it is a car or the car)

[chung]

Suur aitäh, ainurakne! It's good to have your input considering that none of the Estonian textbooks available to me (e.g. Teach Yourself Estonian, Colloquial Estonian, Estonian - Textbook and Grammar) explain it this clearly. I wouldn't be surprised if it's explained here but that's all in Estonian. I'm sure that there are more ways to indicate definiteness but your explanation is very helpful and gets me thinking in the "right way" about Estonian.

As I had hinted at earlier too many Estonian resources for English-speakers try to accommodate us by reporting that Estonian has no definite articles; as if one needs these articles to signal what's definite in the sentence. It's just biased Romance- or Germanic-centric framing and quietly encourages learners to think of our Romance or Germanic equivalents without considering that Estonian does things differently anyway.

[ainurakne]

Võta heaks!

I wouldn't be surprised if it's explained here but that's all in Estonian.

Hmm, I don't think I have ever heard about the terms "definite" and "indefinite" in the context of Estonian grammar.
The only translation to these terms that I am aware of, are "määrav artikkel" (definite article) and "umbmäärane artikkel" (indefinite article) which are usually used in the context of explaining English.

As an Estonian, I often find using articles difficult. Yes, there are cases where choosing between definite or indefinite article is completely obvious. But there are also many other times when I find choosing the right article impossible, or any article completely redundant. It's like English forbids you to be vague or to omit the unimportant.