質問: 例えば、 > > その地方の人々はこの宝物が珍しがっている > > > その地方の人々はこの宝物が珍しいと思っている > > >
回答: The main difference between がる and 思う is that がる is used when **describing how other people** think/feel (or appear to think/feel). がる cannot be used about the speaker. The point is that you can never know exactly what someone else is actually thinking or feeling, even if it may seem obvious. So in general, 思う is avoided when the speaker is talking about how others think/feel. Instead, がる is used to indicate what the speaker believes they are thinking/feeling, based on appearances. From the speaker's point of view, 僕は新しい車が欲しいです is correct, but トムは新しい車が欲しいです is **not** correct because the speaker can't be 100% positive that Tom actually wants a new car. Therefore, the speaker uses がる to indicate what appears to be case, i.e. that Tom seems to want a new car. And accordingly... トムは新しい車を欲しがっています is the correct way to state this from the speaker's point of view.