Does だけが mean "but only" or "not just"?


Earlier today I saw this sign:

![smokers are inconsiderate losers](https://i.stack.imgur.com/t1PTo.jpg)

> 煙{けむり}の行方{ゆくえ}。本人{ほんにん}だけが、他人{たにん}事{ごと}だった。

The English is different enough that I think we can mostly ignore it for the
purposes of this question. It helpfully conveys the message, but I'm wondering
about the grammar of the Japanese, from which the provided English is quite
different.

In particular, I'm wondering about the use of `だけが`. `だけ` is "just" or "only",
and `が` is "but", so my reading of this is "Other people's problem, but
only/just the person themselves." That's not merely **deliberately
ungrammatical** English to convey my confusion, it also seems to convey the
opposite message than intended. It seems to be saying that the smoke is only
just the smoker's problem, no one elses.

From the context and the English provided, I know it's _supposed_ to say, "not
just the smoker, it's other people's issue as well."

But I just don't see how `だけが` means "not just", instead of "but only."

What am I not understanding about `だけが`?




Let's look at some example sentences:

> ゲームとネット **だけが** [生きがい]{いきがい}
>
> 自分 **だけが** 知ってる[秘密]{ひみつ}
>
> [悲しみ]{かなしみ} **だけが** 夢をみる

To put it simply, a strong emphasis is put on whatever comes before the だけが to
mean "The only thing", "The only person", "The only reason", etc. In other
words, translating it as "not just" would be a mistake. It actually means the
opposite, for example you could translate the first example as:

> (Video) Games and the internet are my only reason for living. (Assuming the
> subject is the speaker)

I hope you can see that "not just" doesn't make much sense in the above
sentence. So, based on the above logic, I would translate the sentence in the
poster as:

> Where does the smoke go? **Only** the smoker doesn't care. (Which I think is
> a better translation than what's in the poster :))

As an exercise, how would you translate the last sentence? [悲しみ]{かなしみ}だけが夢をみる

Also, I should warn that these ad campaigns are run by JT (Japan Tobacco)
because they try to brainwash people into believing that smokers and non-
smokers can live in harmony as long as the smokers obey manners, but I
digress..




Let's look at some example sentences:

> ゲームとネット **だけが** [生きがい]{いきがい}
>
> 自分 **だけが** 知ってる[秘密]{ひみつ}
>
> [悲しみ]{かなしみ} **だけが** 夢をみる

To put it simply, a strong emphasis is put on whatever comes before the だけが to
mean "The only thing", "The only person", "The only reason", etc. In other
words, translating it as "not just" would be a mistake. It actually means the
opposite, for example you could translate the first example as:

> (Video) Games and the internet are my only reason for living. (Assuming the
> subject is the speaker)

I hope you can see that "not just" doesn't make much sense in the above
sentence. So, based on the above logic, I would translate the sentence in the
poster as:

> Where does the smoke go? **Only** the smoker doesn't care. (Which I think is
> a better translation than what's in the poster :))

As an exercise, how would you translate the last sentence? [悲しみ]{かなしみ}だけが夢をみる

Also, I should warn that these ad campaigns are run by JT (Japan Tobacco)
because they try to brainwash people into believing that smokers and non-
smokers can live in harmony as long as the smokers obey manners, but I
digress..

