David O. wrote:Note also that after a numeral, you need partitive singular:
10 kysymystä. After other quantifiers, generally, you'll have partitive plural:
paljon kysymyksiä.
The reason the partitive singular is used with numerals is that "conceptually" one is dealing with a portion, or "part", of a whole set...or whole "universe" of something. For example, viisi kirjaa....."five from the whole "set of books".
I've never liked this explanation. First, because logically, there's no reason why five books should represent part of a set while one book doesn't (each individual book within the five is part of the set of five...). Second, and more importantly, because it has no connection to the way the brain actually produces language. No Finn thinks "well, I've got five books, which represent but a fraction of all the books in the world, so I need to use the partitive."
Think about numbers in English. When you hear any number other than "one", your brain primes itself for a plural noun. Similarly, when one hears any number in Finnish other than
yksi, one primes oneself for a noun in the partitive singular. That's all there is to it - there is no "why". It's not a logic puzzle, it's just a reflex.

I certainly agree that once one realizes that the partitive is used for plurals in Finnish it becomes a reflex....and, of course, native speakers who learned the language eons ago don't need to think about why the partitive is used...they just "know".... Further, as a language learner, the objective is to get to the point where it does become a "reflex"...
Yet I wrestled with the partitive and numerals "issue", and the partitive and negation "issue" for quite a while.... I knew what the "rules" called for, but the logic of it escaped me..... The "light went on" when I realized that with numbers greater than one you are dealing with a "portion" of the total number of all that could be.... and it was "cinched" when I found out the partitive was developed in ancient times from the ablative ...the "from" ...case.....
That "one" of something doesn't fit this pattern now makes complete sense to me, as well.... With "one" you are dealing with a "singularity"...a discrete unit of the category and, thus, it, in itself, is "complete".
For me, anyway, this is difficult to clearly articulate. Nevertheless it makes sense.....and it also helps in my overall understanding of how to use the partitive.
Partitive and negation... The concept is "no part of the whole".... Partitive and fractions..... a portion of the "singularity".
Here's a little "mental test" I stumbled on recently which, again, drives home the difference between the accusative-genitive and the partitive:
Consider the word,
ympäri.... it can be both a postposition and a preposition...
...
kaupungin ympäri ...with the genitive (arguably the "accusative") ...carries the sense of going around the city in a circular, "defined" pattern.
...
ympäri kaupunkia....with the partitive....implies a vaguer, less well-defined, "all over" sense....
I think you'll find that native speakers will always be picking up on these kinds of distinctions between partitive use and genitive-accusative use.....and most of them will just "know"... Unless they are unusually well-trained in grammar, they probably won't be able to explain it very well....
[Aside: Here's something I've just been thinking about:
"We saw infinite dogs."...admittedly not the best English.... Somehow this implies to me, emotionally, "all dogs" ...though, intellectually, it actually doesn't mean that...it's an unspecified, unbounded number....
I'm sure in Finnish the translation would be:
Katsoimme ääretön koiraa......
...How about this....
"There are 1,000,000 elephants in the universe. We saw 1,000,000 elephants."
Maailmankaikkeudessa on miljoona norsua / norsut. Katsoimme miljoona norsua/norsut..... OK, OK....even though we "saw" the complete set of elephants, I simply just "know" that the partitive,
norsua, would be used here....

]
[Edit: Here's another little "twist" ...if you want to say there was an elephant in the refrigerator you would have to say it this way:
Jääkaapissa on norsu......you couldn't say....
*Jääkaapissa on norsun.....This is an example of a Finnish existential sentence...there is no "overt" verb and so you need the nominative form....but, in a sense, it still implies "completeness" and is considered an accusative form.... If it were milk
maito....an "uncountable" noun.... You would have a choice.........
Jääkaapissa on maitoa ...tai....Jääkaapissa on maito. ...they have slightly different meanings....and with a non-existential sentence ....
Ostan maitoa.....Ostan maidon. ..."I bought some some milk"....."I bought the milk."]