Since 本来 means both "originally" and "of course", how can I determine if 他本来是老师 means "he was originally a teacher" or "he is of course a teacher"?

Question

CC-CEDICT: 本来 (běn​lái​) original / originally / at first / it goes without saying / of course

I'm interested in the two adverb meanings of 本来, which my dictionary's definitions are:

1. （副）从前，先前。
2. （副）表示理所当然。

In some contexts, we can easily distinguish between these two meanings. However, sometimes it's not so simple.

他本来是老师。

I get the impression this is ordinarily interpreted as meaning "he was originally a teacher", but I don't see why it cannot also be interpreted as meaning "he is of course a teacher" via the second adverb meaning above.

Question: Since 本来 means both "originally" and "of course", how can I determine if 他本来是老师 means "he was originally a teacher" or "he is of course a teacher"?

Answer 1

The meaning of "of course" is usually used in a structure of 本来+就. In your example without 就, I don't think 本来 can mean "originally".

A good explanation can be found here.

Answer 2

• A: 他原本是做什麼的? B: 他本来(originally)是老师. This answer is a plain statement of fact - He originally was a teacher (it happens in the past, most likely not for now).

• A: 他看起來像是教書的. B: 他本来就(of course)是老师. This answer is affirming the assumed position of the object in the question, with a slight sense of ridicule - He is a teacher without saying (it implies now, at this moment of speaking).