논지가 · 논지를
main argument, thesis, point (of an argument)
Example
글쓴이의 논지가 분명하지 않아서 이해하기 어려워요.
The writer's main argument isn't clear, so it's hard to understand.
Word parts
논 discuss+지 meaning
Literally 'meaning of the argument'.
Good to know
논지 = what the argument says; 논조 = how it says it (its tone).