We need to be careful when talking about other people’s emotions or feelings—I’m talking grammatically here. Japanese makes a distinction between what you know based on direct experience and what you believe based on judgement. When we’re talking about other people’s emotions and feeling only the latter applies—we cannot know directly how someone feels because we cannot be them. In English, we sometimes make this distinction with words like “seem” or “look”:

さびしそうなかおをしているけど、大丈夫だいじょうぶ
You look lonely. Is everything alright?

But in other cases it makes no difference whether we’re talking about our own desires or someone else’s.

I want a beer.
They want a beer.

Japanese requires this distinction to be made, and to do so we turn adjectives into verbs with 〜がる.

  • For i-adjectives we replace the い with がる.
  • For na-adjectives we simply add がる.
English Adjective 〜がる
Scary こわ こわがる
Dislike いや いやがる
Embarrassing ずかしい ずかしがる

Note that this does not apply to ALL adjectives—only those that pertain to feelings and emotions (as all three of the above do).

彼女かのじょとなりでタバコをうとすぐにいやがるよね。
She’ll immediately protest if you smoke next to her.
うちの夜中よなかにかすかなおとでもこえたらこわがってわたしたちの部屋へやこんでくるのよ。
If my child hears even a faint sound in the middle of the night he gets scared and comes dashing into our bedroom.

Because our former adjectives are now working as verbs the object particle を is required.

わたしはビールがほしい。
I want a beer.
かれらはビールをほしたがっている。
They want a beer.

〜がる is often used with the “want” form of verbs which, as we know, behave like adjectives.

English Dictionary Want 〜がる
To know りたい りたがる
To eat べる べたい べたがる
To do する したい したがる
子供こどもあたらしいことをつけるとりたがる。
Children are curious when they find something new.
彼女かのじょいえにいたがるタイプです。
She’s the stay-at-home type.
あいつはおんながいるといつもカッコつけたがるよね。
He’s always a show-off around girls.
ぱらって富里みさとさんに告白こくはくしたというのはかれけたがる話題わだいだろうな。
I imagine he’ll want to avoid the topic of his getting drunk expressing his feelings to Misato-san.

The grammatical rules are that we can’t make a definitive statement about someone else’s feelings or desires without using 〜たがる. We can, however, say the following:

うちの長男ちょうなんくるましいんだって。
My eldest says that he wants a car.

Here we are not making a definitive statement about his desires—just quoting what he said.

沙織さおり来年らいねん結婚けっこんしたいらしいよ。
I hear that Saori wants to get married next year.

Because we use らしい to infer that it’s something we’ve heard the use of たい is acceptable.

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