と思います vs. と思っています


Consider the following sentences:

> 引越しをして本当に良かった **と思います** 。
>
> 引越しをして本当に良かった **と思っています** 。

If I use と思います, does the sentence become more formal?




It's not about formality, but meaning difference.

Both are translated "think", but the plain ending 思います（思う） stands for an
instant judgment at that moment, reacting to an event or responding to a
question; or begin to think. The stative 思っています（思っている）, on the other hand,
means holding an idea or belief in one's mind for a duration.

Another explanation, if you prefer, is that 思う : 思っている is analogous to _put
on_ : _wear_.

> 私を誰だと **思っている** のだ。 _Who do you think I am!?_  
>  × 私を誰だと **思う** のだ。

In the examples above, only the first one tells the meaning in English. The
second is very, um... prosopagnostic (if grammatical in any way).

> この映画を見たら、人生も捨てたものじゃないと **思いました** 。 _When I watched the movie, I thought the
> life is not as bad as it seems._  
>  × この映画を見たら、人生も捨てたものじゃないと **思っていました** 。

In these examples, たら indicates immediate trigger, so only the first sentence
is grammatical.

**Related**

  * [Difference between volitional +と思う and volitional+ と思っている](https://japanese.stackexchange.com/q/40145/7810)
  * [Vようと思います／Vようと思っています](http://www.coelang.tufs.ac.jp/mt/ja/gmod/contents/explanation/066.html)




It's not about formality, but meaning difference.

Both are translated "think", but the plain ending 思います（思う） stands for an
instant judgment at that moment, reacting to an event or responding to a
question; or begin to think. The stative 思っています（思っている）, on the other hand,
means holding an idea or belief in one's mind for a duration.

Another explanation, if you prefer, is that 思う : 思っている is analogous to _put
on_ : _wear_.

> 私を誰だと **思っている** のだ。 _Who do you think I am!?_  
>  × 私を誰だと **思う** のだ。

In the examples above, only the first one tells the meaning in English. The
second is very, um... prosopagnostic (if grammatical in any way).

> この映画を見たら、人生も捨てたものじゃないと **思いました** 。 _When I watched the movie, I thought the
> life is not as bad as it seems._  
>  × この映画を見たら、人生も捨てたものじゃないと **思っていました** 。

In these examples, たら indicates immediate trigger, so only the first sentence
is grammatical.

**Related**

  * [Difference between volitional +と思う and volitional+ と思っている](https://japanese.stackexchange.com/q/40145/7810)
  * [Vようと思います／Vようと思っています](http://www.coelang.tufs.ac.jp/mt/ja/gmod/contents/explanation/066.html)

