What is the deal with akkusatiivi and genetiivi?

 Today, I’ll be answering two questions on the same topic. Here both questions first:
 
Enitan writes:

Hei Mari, how are you today? Could you help with a link that gives a distinct explanation on akkusatiivi and genetiivi? I've searched through your blog but couldn't find anything related to it. Thanks
 
Sigrid writes:

Moi! Onko akkusatiivi vielä suomenkielessä? Mulla on ikivanha suomen-norja oppikirja, ja siellä on akkuusatiivi, mutta uusissa kirjoissa se on pikemminkin genitiivi, vaikka se on erilainen (genetiivi yksikössä ja nominatiivi monikossa, ja persoonapronominit ovat myös erilaisia). Toivottavasti ymmärrät mitä tarkoitan!

My translation:

Hi! Is the accusative still in the Finnish language? I have a very old Finnish-Norwegian textbook, and they talk about the accusative, but new textbooks will rather talk about the genitive, though it’s differen (genitive in the singular and nominative in the plural, and personal pronouns are also different) I hope you understand what I mean!
 
My answer:
 
Hi Enitan and Sigrid, thanks for the great questions! There's a bit of a terminology issue here, as akkusatiivi or accusative can mean different things. As Sigrid noticed, older and newer books use different words to talk about the object. 
 
In most modern grammars, akkusatiivi means the object forms of the personal pronouns:
  
Näin sinut eilen.
I saw you yesterday. 
sinut = akkusatiivi of the word sinä 
 
The corresponding question word is also in the accusative form:

Kenet näit eilen?
Who(m) did you see yesterday? 
kenet = akkusatiivi of the word kuka
 
In every other type of word, the same form is the genitive case:

Näin Marin eilen.
I saw Mari yesterday. 

Mari is in the genitive case, which tells us that Mari is the object of the sentence, the person being seen.                
 
However, in older grammars, they usually refer to the form Marin as akkusatiivi as well, which is pretty confusing. And also nominative objects might be called accusatives.

In modern grammars, there are two types of objects:

1. Partitive objects (partitiiviobjekti). These are always in the partitive case. 

Juon kahvia.
I’m drinking coffee or some coffee.
Minun täytyy juoda kahvia.
I have to drink coffee or some coffee.

2. Total objects (totaaliobjekti). These can be in the genitive, nominative or accusative case. 

2.1 Genitive (genetiivi):

Juon kahvin.
I’m drinking a coffee (I have a defined amount and I’m drinking all of it).

2.2 Nominative (nominatiivi eli perusmuoto)

Minun täytyy juoda kahvi.
I have to drink a coffee.

2.3 Accusative 

Näin heidät eilen. 
I saw them yesterday. 
 
If you speak a language that has something called the aspect, like Slavic langugages or Hungarian, you might find that this sounds familiar. Slavic languages and Hungarian have different verb forms to describe ongoing processes and actions that are over and done with. Finnish expresses the same thing by changing the form of the object.

So to recap, the case of the total object is either the genitive or the nominative, or for personal pronouns and their corresponding question words, the accusative (minut, sinut, kenet). In older grammars, these were called accusative objects instead of total objects, and kahvin was said to be in the accusative case. This was confusing because the same word was used for both the case and the phenomenon, and also the accusative case looks exactly like the genitive in modern Finnish, so some linguists decided to make the terminology clearer by starting to talk about total objects instead of accusative objects.

However, changing the terminology resulted in even more confusion, because now we have two sets of competing terms flying around. If you’re already familiar with the concept of accusatives, it might be useful to use the old terminology, but if you’re not, I’d say stick with the new terminology. In my classes, I often find myself talking about genetiivi-akkusatiivi to help everyone follow along (though I’m not sure how helpful that monster of a word really is).
 
If you’d like to read about all this in more detail, the wonderful website Uusi kielemme has a very comprehensive article about the object in English. 
 

Haluan syödä tämän omenan.
Picture by pasja1000