How to decide on which part to use honorifics?

Question

I have seen that sometimes the honorific is used for only some part of the sentence, such as at the subject particle or verb. For example,

할머니가 식용유를 사려고 슈퍼마켓에 가셨어요.

In this sentence, the honorific is not used at the subject particle (께서). In other cases, honorifics are not used at all.

So I wonder how to decide if I use the honorifics and on which part to use?

Answer 1

There are the three factors for Korean honorific speech: (a) subject honorification, (b) object exaltation, and (c) speech styles. (You may refer to this.)

Your question and example relate to the first one. These words belong to it:

1. -(으)시- (meaning "-으시- or -시-")
2. -께서
3. others used for honorific speech (-님, -분, 계시다, 잡수다, 주무시다, 아드님, 따님, 진지, 말씀, 댁, 생신, 춘추, ...)

할머니가 식용유를 사러 슈퍼마켓에 가셨어요.

Because this includes -시- (가시었어요 is shortened as 가셨어요), the sentence shows the subject honorification although it does not have -께서.

할머니께서 식용유를 사러 슈퍼마켓에 가셨어요.

This follows a reference, 표준 언어 예절(2011) - 경어법. It sounds better to me.

할머니께서 식용유를 사시러 슈퍼마켓에 가셨어요.

This sounds a bit awkward to me (because 가다 is the last verb and I usually use -(으)시- for the last verb/adjective only); it is also correct but not advisable according to the reference.

I have heard all the three kinds of sentences. People tend not to use -께서 for casual conversation. When you have to follow the guidelines (for example, in formal situations), however, you should use -께서.

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The national institute mentions why 께서 is not often used in speaking Korean as the following:

존칭의 조사 '께서', '께'는 대화에서는 잘 쓰이지 않는다. 용언의 '-시-'로도 충분히 높였다고 생각하기 때문이다.

That is, people think using -(으)시- is sufficient for the subject honorification in speaking Korean.