grammar - Different meanings of こわい

I was watching this video (it's actually a really good series, despite the odd presentation). In it, there is the example:

おばけがこわい。
Ghosts are scary.

No problem there, but the series has been talking a lot about how the zero-pronoun marks the subject in a sentence, and that the default pronoun is "I" (in the absence of other context). It then goes on to say that こわい on it's own means "I am scared", i.e. we took away the subject and it has now been replaced with the default "I".

This of course means that the meaning of こわい has changed from "to be scary" into "to be scared". But is this really what's happening? In the case of just こわい, why can't we assume that the zero-pronoun is actually "it" rather than "I"? Then we have "It is scary" which basically is the same as "I am scared", and then the adjective doesn't have to change meaning?

I also wonder what happens if we explicitly write the subject "I":

私がこわい。

Does this mean "I am scared" or "I am scary"? I suspect it is still "I am scared", so how would you actually say "I am scary"?

Answer

怖い indeed means both "to be scary" and "to be scared" depending on the context. You may feel this is insane, but English has similar examples, too, so let me explain about this first.

In English, "I am sad" means this person is feeling sorrow, but "The news is sad" does not mean this news is feeling sorrow. Why? Because "sad" has two distinct meanings, "to feel sorrow" and "to cause sorrow". In English, "He worries about it" and "He is worried about it" mean almost the same thing. Why? Because "worry" has two meanings, "to feel anxiety" and "to cause anxiety". In both examples, you can easily choose the right meaning from the context. But "worry" is a very confusing word to a learner like me.

Japanese 怖い works similarly to English "sad". 怖い means both "to feel fear" and "to cause fear". You have to accept this fact and learn to choose the correct meaning using your common sense.

• 私は怖い。
  [after talking about a risky plan] I am scared.
  [in a self-introduction] I am scary.



• おばけは怖い。
  Ghosts are scary (beings).


• 彼は怖い人だ。
  He is a scary person.


• 怖い人はこの映画を見なくていい。
  Those who are scared don't have to watch the movie.

Many Japanese adjectives including 嬉しい, 悲しい and 楽しい work similarly.

• 彼は楽しい。
  [in an introduction] He is a fun person.


• 私は楽しい。
  [in an amusement park] I am having fun.

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Now, what about おばけが怖い? Now we have が instead of は. When we say おばけが怖い, it no longer means "Ghosts are scary (in general)", but there are several possible ways to interpret it:

1. I am scared of ghosts. / Ghosts are scary to me.


2. (Hey,) Ghosts are (now) being scary (although ghosts are normally not scary).


3. It is ghosts that are scary/scared.

The first one is a well-known "double subject" interpretation. It's the same as 私はおばけが怖い but 私は is omitted. I would say this is the natural interpretation when there is no particular context.

The second interpretation is rather special; it is a 現象文 that is using neutral-description ga to report a temporary fact. Can you see the critical difference between these sentences?

• ママは怖い。 My mom is (always) scary. (as a known fact)


• ママが怖い。 My mom is scary (now, although she is usually calm)! (new information)

• 財布はない。 I don't own a wallet. (as a known fact)


• 財布がない。 My wallet is missing! (new information)

However, it's difficult to interpret おばけが怖い as a 現象文 because ghosts are normally scary.

The third interpretation is using exhaustive-listing ga. But this makes sense only in a certain context.

As a result, the only natural interpretation of おばけが怖い when there is no context is "I am scared of ghosts" with the omitted topic 私は.

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How about 私が怖い? This does not mean "I am (usually) a scary person" because it's using が instead of は. But it cannot be a 現象文, either, because it doesn't make sense to report one's own anger like this. So the only natural interpretation would be exhaustive-listing ga.

• 私は怖い。 I am a scary person. / I am scared.


• 私が怖い。
  It's me who is scary. (as a response to a question like "Who is the scariest person in your family?")
  It's me who is scared. (as a response to "Our kids are not scared of this roller coaster!")