Japanese phrase
どうしてそう思いますか？ dō shi te sō omo i ma su ka
Meaning
Why do you think so?
When to use it
Asks why someone has a certain opinion. It is a neutral and polite way to ask for the reasons behind a stated view.
Example dialogue
彼は来ないと思います。 kare wa ko na i to omo i ma su
I do not think he will come.
どうしてそう思いますか？ dō shi te sō omo i ma su ka
Why do you think so?