23397
I was talking to one of my friends about these particles (He is a native
speaker of the language, and I thought he might know) and here's what he told
me:

私は芋が彼を殺すと思います => I think the potato is killing him.

I asking him about why to write と instead of こと, and he couldn't explain it.

Ok, but why is it と? not こと? Every website that tries to explain it makes it
seem like this would be correct. What am I missing?

(And yes, I know that phrase sounds stupid, but it was the only one that I
could think of.)
CC BY-SA 3.0
2015-03-22T16:13:18.153
23395
2016-08-20T05:59:50.463
2016-08-20T05:59:50.463
11104
9669
question
grammar particles
When to use と and こと?
I will preface this answer by saying there is no hard-and-fast rule, like with
most particles, about when to use と and when to use こと. So, I'll try to stick
directly to the context you provided.

# と

The particle と is used in quite a few ways, but in this particular case (haha,
get it?) it's a [**quoting particle**](http://www.learn-japanese-
adventure.com/japanese-particle-to.html).

> 明日｛あした｝も雨｛あめ｝です。  
>  It will rain tomorrow, too.
>
> 明日｛あした｝も雨｛あめ｝だ **と** 言｛い｝いました。  
>  [Someone] said it will rain tomorrow, too.

It works a similar way for 思｛おも｝う. If something is a thought of yours, say,
that "apples are tasty," the phrase 「りんごがおいしい」 becomes quoted.

> りんごがおいしい **と** 思｛おも｝います。  
>  I think apples are tasty.

The construct ～と思｛おも｝う is very common, and there's only a few circumstances in
which you will see 思う without being preceded by a quoting particle (usually
と).

# こと

However, こと is much different. It is not a quoting particle. It literally
means "thing" (an abstract thing, not a physical thing). You might see it in a
few contexts, generally following verbs.

> 日本｛にほん｝に行｛い｝った **こと** がありますか。  
>  Have you ever been to Japan? _(lit. Have you ever done a thing where you
> went to Japan?)_
>
> 泳｛およ｝ぐ **こと** ができますよ。  
>  I can swim! _(lit. I can do swimming things!)_

(There are many more situations you'd use it in, beyond these examples.)

So, why can't you use こと in your initial example?

> ｘ 私｛わたし｝は芋｛いも｝が彼｛かれ｝を殺｛ころ｝す **こと** 思｛おも｝います。 (Wrong!)

This is ungrammatical and would awkwardly translate to English as something
like, "I think potato to kill him." Over time, and as you get used to the
usages of ～と思う, [verb]こと, and so on, you'll see which ones can be used in
which situations.

Hopefully this sort of explains the difference.

# Further reading

  * [Expressing One's Thoughts](http://japanese.about.com/library/weekly/aa061701a.htm) (about と思う)
  * [“verb (dictionary form)+ koto/no + verb” & “te-form verb + verb”](https://odatomoko.wordpress.com/2010/06/18/verb-dictionary-form-kotono-verb-te-form-verb-verb/) (some usages of こと)
CC BY-SA 3.0
2015-03-22T19:23:45.307
23397
2015-03-22T19:23:45.307
2020-06-17T08:18:27.500
-1
3035
23395
answer