# Definite article and “only”

I wrote:

Here one may use the average value of the first and second squares instead of only the second square.

I doubt if I must write

Here one may use the average value of the first and second squares instead of the only second square.

Which is correct? If both are correct, what is the difference in meaning?

As G-Cam says, "only the X", means that there are several things under discussion, but right now the one we are interested in is the X.

"The only X" says that there is only one thing that qualifies as X.

In your example, talking about the "second square", the second usage doesn't make much sense. Presumably there is only one square that is "second". I wouldn't suppose there could be 5 or 10 "second squares".

But suppose I said something about the "red square". If I said, "Consider the only red square", that would mean that while there may be many squares, only one of them is red. I am emphasizing that there is only one red square.

"Consider only the red square" says that I am calling your attention to the square that is red. The fact that I use the singular "square" implies that there is only one, but the sentence structure is not emphasizing that there is only one, but rather assumes this, and then emphasizes that this is the one we are interested in.

Both are grammatically correct but they do mean different things.

Your first example - only the second square - is drawing attention to the second square specifically (as opposed to both of the squares). The position of "only" gives the sentence a breakdown like this:

"...only [the second square]."

"The second square" refers to a specific object. This is almost certainly the correct phrasing of your intention.

The second example - the only second square - is broken down like this:

"...[the only] [second square]."

Since "the" is not immediately before "second square", this sentence is talking about "second squares" in general (rather than the specific second square you most likely are considering). It conveys a meaning that there is an object that is called a "second square" and there is only one "second square".

You should in all likelihood use

... instead of only the second square.

The other way suggests that you are overly fussy about there being just one second square.

We interpose only between determiner and noun

It is the only car we have.

when the meaning is "no other one exists/there is no other one" (adjectival only, existential quality).

When the meaning is "alone, by itself, not with anything else" (adverbial only, manner) it would be

use the second square only

use only the second square

• But it's perfectly possible to say It is only the car we have (we don't have anything except the car) or It is the car only we have (no-one except us has this car). The thing is we normally try to position only immediately before the specific element it's intended to modify. In your example, that's just car, not the car. – FumbleFingers Sep 7 '16 at 15:00
• @FumbleFingers your "only we" example is not germane to the original question as it has nothing to do with the placement of only relative to a determiner. Why not put up your own answer: "put only immediately before the element it is intended to modify"? – Tᴚoɯɐuo Sep 7 '16 at 16:33
• How do we know what's "not germane to the original question"? You've assumed it's obvious to everyone that OP is only concerned with contexts involving [determiner] only [noun], and that the first line of your answer should therefore be understood to be relevant to that context only. Looking again at the way you've presented things I see the first line isn't in fact a "general prescription". But that's what it looked like to me when I first read it. That's to say if I'd put my reading glasses on I wouldn't have been surprised to see a full stop after ...and noun. – FumbleFingers Sep 7 '16 at 16:49
• I refer you to the title of the question. – Tᴚoɯɐuo Sep 7 '16 at 16:51
• I don't know why two clever guys like us are arguing over this minor point. If you'd put your When the meaning is... clause before the initial assertion I wouldn't have misparsed it as a general rule rather than being restricted to one specific context. In which case I wouldn't have felt moved to point out that there are other contexts where it doesn't apply. Okay, you may say I'm not in fact smart, and/or that I should pay more attention to your text. But I'm a competent native speaker, and if it caught me out it might well mislead some of our target audience here. – FumbleFingers Sep 7 '16 at 17:12