Over on Old Teachers Never Die… a couple of weeks ago Antony Shen asked:
Speaking of “subject-verb agreement”. I hope you don’t mind answering me a simple question (not directly related). With countable nouns, in scientific styled sentences, do you say “0.1 apple” or “0.1 apples“? (as in zero point two rather than one fifth of an …) Also, in the case of negative numbers, do you say “-1 apple” or “-1 apples“? Or shall I ask, what is the definition of “plural”? “greater than one” OR “anything other than one”?
I replied:
To deal with your second question first: countable nouns form plurals; mass/uncountable nouns don’t. This gets a little more complicated because some nouns may be either countable or mass/uncountable, depending on how they are being used. “Wheat” for example may be both: ten kilos of wheat is uncountable; several types of wheat is also uncountable; there are several wheats used in this mix is countable.
OK, with countable nouns: I would say 0.1 apples for grammatical reasons, though I agree it is not logical! I guess you could say 0.1 of an apple just as you say one-tenth of an apple, but it seems we don’t. Interesting question.
Antony:
What about “-1 apple(s)”? “-1” (minus one) is less than “0” (zero). Since we say “zero apples” or “no apples”, and in the case of one less apple than nothing, should it be “-1 apples” or just “-1 apple”?
Me:
If the number one is used, whether it is +/-1, the following noun will be singular. So it would be -1 apple. We’re talking grammar, not logic; and yes we say zero apples, probably because zero is thought of as a number that is not one, even though zero is neither singular nor plural logically.
Antony:
Thank you very much for the answer. In Mathematics (Number Theory), unity means 1 (one), and only the positive one, and there is only one unity. In grammar, it seems like there are two cases for singular nouns. If plural is defined as “any amount other than one”, then, zero is plural, as well as -1.
Me:
Unfortunately mathematical theory may have little correlation with grammar or usage. The concept of grammatical number is not a mathematical concept strictly, so the word one is always singular, whatever mathematical theory may hold. English probably treats zero as a plural because the grammar gives only two choices, and the word zero is not the word one: we also say, incidentally, there are no apples on the table (countable) but we say there is no rice on the table (uncountable). At least we don’t have to worry, as the French or the Italians do, whether apple, rice and table are masculine or feminine! And Chinese survives quite well without marking nouns as singular or plural, as I am sure you know.
Anyone want to contribute more ideas? I found it quite intriguing — but then perhaps I am strange…
English, ESL -- and more! 
TGom Hammond
September 8, 2008 at 7:54 am
I can assume from this logic that 1/2, 1/3, 1/4 etc. would be also treated as plural, since they are not one and since they imply that more than one is referred to in the phrase or a sentence.
Neil
September 8, 2008 at 9:48 am
Always dangerous to assume natural languages work logically. In this case those fractions seem to take their number from the word “one” and so are singular. “Two thirds” , for example, would then be plural.
Karl
November 8, 2008 at 12:53 am
Look to Norwegian:
ikke => not
noen => some
ikke + noen = ingen
ingen => no
eple => apple
epler => apples
noen epler => some apples (pl.)
ingen epler = ikke noen epler => not some apples = no apples (pl.)
Your language has been so much influenced by other languages that you can no longer easily draw such conclusions. But you can still go back to the roots!
Negative numbers did not exist at the time our languages were formed. The rule in Norwegian has been to let the closest word to the verb decide whether it be singular or plural. Since one is closer this indicates a singular verb. However, in English the combination of words has come to decide whether the verb be singular or plural. That is more difficult to sort out. Minus is a word that cannot conjugate verbs on its own, so I would recommend that you say minus one apple (sing.), as is historically correct.
Neil
April 15, 2009 at 9:12 am
A reader wants to know if the information here about the “number” of zero applies in other languages too. For starters, this could only apply to languages which indicate number grammatically, I suppose. Does anyone want to add anything?
Eric
May 14, 2009 at 2:32 am
I’m probably a little late on this one… but I’ve started looking into the fractional quantities of nouns today and it seems really strange.
If in proper English, saying 0.1 apples is the accepted form (i wouldn’t know as English is not my mother tongue), how would you, theoretically of cause, divide between 0.1 of a certain apple (0.1 of an apple) and 0.1 of apples = of all the apples in the world?
Is it really normal to say “0.1 apples” in English when referring to one tenth of an undefined(/undetermined) apple?
Or would a native speaker still use “0.1 of an apple”?
Paul Charlebois
December 6, 2009 at 2:56 am
This discussion is really interesting since some subscribers include comparisons with toher languages. My mother language is French. Our grammar states a simple, and logic, rule: “A noun preceded by a number greater or equal to 2 must be written in the plural form”. We would then correctly write “0.1 pomme”, “2.5 oranges” and “1.7 point”, which is, in English, “0.1 apple”, “2.5 oranges” and “1.7 point”.
Michael
May 16, 2011 at 4:31 pm
When it comes to decimals, we usually pronounce them wrong anyway. The figure, “0.7,” should not be pronounced, “zero point seven,” but rather, “seven-tenths.” “Point” is a verbal shorthand by which we are describing what we see written rather than properly translating the number from mathematics to English. If the value to the left of the decimal is greater than zero, the decimal is supposed to be pronounced, “and,” rather than, “point.”
If the unit in question is, say, oranges, and the figure counted is 2.5, the proper way to describe it verbally would be to say, “2 oranges and five-tenths,” although it’s much better form to reduce the fraction and say, “2 oranges and one half.”
If a hockey player scores .723 goals per game (this is the way it is typically written in sports articles), the proper way to say that would be, “this player scores 723 thousandths of a goal per game.”
We tend to pluralize the wrong word. When we say, “.7 potatoes,” we are correct to perceive that something needs to be pluralized, but we choose the wrong word in “potatoes.” It is the place value, not the counted items, that must be pluralized in this case. Seven-tenths of one potato. Keep in mind that everything after the decimal means, “x of one whole,” and one is always singular.
Abstract numbers such as zero and negative integers are trickier. I suggest that using the same rules from positive integers on their negative counterparts will always sound correct (“negative 1 apple,” “negative three-tenths of one apple,” “negative 2 apples and thirty-four hundredths,” etc.) I doubt this is technically correct though, because according to the dictionary, plural means “consisting of, containing, or pertaining to more than one,” and singular means, “denoting a word or an inflected form of a word indicating that not more than one referent is being referred to or described .” [Dictionary.com] By this logic, all whole numbers lesser than 1 ought to remain singular and thus we should say, “zero apple,” “negative 1 apple,” “negative 2 apple,” “negative 3 apple and forty-four hundredths,” etc.
Sometimes we say things that sound correct even if they are not technically correct. Sometimes things sound correct merely because everyone says them incorrectly. I suspect that this is a case in which we strive to conform rather than to be correct.