Thanks a lot. But, would you tell me why we can't remove the word "of" in the sentence?
Apologies for my late reply. Sometimes the relative pronoun
that can be omitted when it refers to people or things in the object position.
"My philosophy is
that of a Buddhist economist."
My philosophy is
of a Buddhist economist [
object position].
Of is a vital component to the meaning of this sentence because it is a preposition that indicates the derivation (source) of your philosophy.
"My philosophy is a Buddhist economist."
It's funny to imagine that an abstract noun such as philosophy having a physical form. This is what happens when you remove the word
of from the sentence; you are indicating that your philosophy is literally a Buddhist economist.