Why does not use 'si' in this sentence 'Ŝi pensas, ke ŝi vidas grandajn insektojn.'

Question

'Ŝi pensas, ke ŝi vidas grandajn insektojn.'

In this sentence, I thought the second 'ŝi' should be 'si' in the context that the first and second 'ŝi' refer to the same woman.

Why was 'ŝi' used here instead of 'si'?

Answer 1

Si refers to the subject of the verb phrase it is in. In your example sentence, there are two verb phrases in the one sentence, so there are also two distinct subjects. In this case the two subjects are the same person, but you can not use si in the second part because the ŝi is the subject of the second verb phrase meaning if it was si it would refer to itself and that wouldn’t make any sense.

It is similar to a sentence with kaj or ĉar:

Ŝi pensis kaj ŝi vidis.

Ŝi pensis ĉar ŝi estas inteligenta.

In those two examples there are two verbs so there are two subjects and it wouldn’t make sense to use si in the second part.

On the other hand if the second part is only separated by a preposition then in that case there is only one verb and it makes sense to use si:

Ŝi parolis al si mem.