Grammar. Singular and plural?

One of the main reasons why plural marking exists is to obviate the need for an adjective. "Dog" is ambiguous, is there one or more than one? A single sound can disambiguate it, "dog" versus "dogs". In many languages of the world there are three numbers marked on nouns--singular, dual (two), and plural (more than two). In a number of Pacific languages there are four numbers marked on nouns--singular, dual, trial (three) or paucal (a few), and plural. Singular is not an "exception", it is one of two equal options in most languages. Actually, "plural" is the exception in European languages because it requires special marking. In most languages, singular is unmarked and plural (dual, trial, and paucal) is marked, but in Africa BOTH singular and plural are marked differently.

EDIT: Actually, I want to say a little more about the "exception" comment. There are three natural numbers based on their frequency in human language--one, two, and more. But the notion of "exception" has two avenues of approach--semantic and grammatical. Semantically, the notion of an exceptional number completely depends on what you are talking about. Things that naturally occur in discrete units are normally singular--tiger (you would never see more than one in the wild), shield (you would never own or use more than one), head (one per body), sun (just one visible), moon, sky, river (you never see more than one at a time), etc. For talking about these things, singular is normal and plural or dual is the exception. Some things occur naturally in pairs--eyes, arms, legs, parents, etc. The normal number for these is dual and singular or plural is the exception. Other things naturally come in herds or greater numbers (we'll ignore the question of mass nouns like sand)--antelope, birds, trees, arrows, children, etc. For these things, plural is the norm and singular or dual is the exception. Indeed, in some languages, number is marked in such ways--singular is unmarked for countable, solitary things; dual is unmarked for paired things; and plural is unmarked for plural things. The marking is the grammatical aspect of natural or exceptional number. In Europe, singular is the norm and plurals are marked, that is, exceptional. In Africa, marking both singular and plural is typical, so you really can't speak of normal or exceptional numbers in the grammatical sense. In Chinese and many other East Asian languages, number is unmarked as a grammatical category, so you can't speak of normal or exceptional in any sense, because the category of number is irrelevant for these languages. You see, you cannot claim that "singular is exceptional" in either a semantic sense or a grammatical sense.

I don't think the singular is an exception to the plural, and your example of understanding "three car" suggests that you don't either (or you would have said "one cars").

Many languages appear to be losing distinctions, not gaining them. English for example no longer distinguishes between plural "you" and singular "thou". The spelling of plural forms in French shows that they were once distinguished from the singular, but now in (spoken) French, very few words show a difference between singular and plural (on the noun itself).

So you're right that "three car" is perfectly understandable, but that doesn't make the phrase any less an example of the concept of plural.

No, you see one form is not enough, because first of all, there are many singular nouns which do not have a plural (music, faith, honey, milk, iron, etc) and lots of plural nouns which do not have a singular.

Besides, you don't always use a numeral because you don't always know the quantity and when you need to use possessive pronouns, for example, I really think it's necessary to realise that a person own more than one object, ot that more people (rather than just one) own something.

Just don't go into the judicial field, ok? Cause you could cause a lot of trouble. If you had 3 car and someone stole two from you, according to your judgement, you would have one car, but that wouldn't make much difference to you would it?

It is an arbitrary rule as is most of language. Many languages assign gender to things like tables and trees which do quite nicely without gender in English. It does make things a whole lot easier to understand when we use pronouns or omit other indicators like actual numbers. Compare "a woman is a liar" and "women are liars". Unless you add the word one or some to the second statement, it sounds like a condemnation of all women and you could get slapped.

Uh because there's singular, and then there's plural. One? Singular. More than one? Plural. We have things called rules. Rules make things run smoothly. Standardized rules help people communicate and understand.

People who have trouble understanding this, and complain that it's too much trouble to make the distinction need to spend more time in school.

I'm tired of seeing stuff like: "me no penis ouch burn girl like it but don't no what i uh dum i know no houw tu speel werds." How stupid is America getting?!!!!

Zero, one, two and many. None, one, couple, at many. I guess they didn't teach you how to count or to express cardinality in language.

As for you premise, one mean a single (hence the word singular) and is opposite of many. It is not an exception but current standard practice.

English has been dumbed down for years now.

It is to have music to it as well as simple communication.

Would you be happy with everyone just grunting and pointing at the breakfast table or dinner table?

I don't think so. That would be the ultimate communication and the ultimate dumbing down.

you need to get laid.