「星が見えない＝Stars can't be seen」 but 「目が見えない＝Eyes can't see」, why?

Question

Are the two 「が」 different?

Is 「目が見えない」 (at least in principle) ambiguous (eyes can't see / eyes can't be seen)?

Answer 1

Yes.

見える

1. (divalent) A が B に見える "A is visible to B".

   大切なものは目に見えない。 What is essential is invisible to the eye.

2. (divalent) A が B に見える "A looks (like) B".

   「でつ」がスヌーピーの顔に見える。 "でつ" looks like Snoopy's face.

3. (monovalent) A が見える "A can see things".

   [吸血鬼]{きゅう・けつ・き}は夜でも見える。 Vampires have night vision.

Answer 2

The particle "が" is not different in your examples, but the verb "見える" has more than one meaning.

Theoretically, you are correct. A person like Altair might be described as 目が見えない人.

Of course you have to say フードのせいで外から目が見えない人 or something like that in order to avoid confusion.

Similar things happen in English, and the natural interpretation greatly changes depending on the subject. It's always difficult to answer why, but I think that's something you have to learn.

• I look at the dog. vs. The dog looks cute.
• I read the sign. vs. The sign reads "No trespassing."
• I sold the book. vs. The book sold well.