Unlike the related term 議 (which also means to discuss)、論 is not reciprocal. I.e. you need two people to 議, but only one to 論.
RON Reagan talked in his speech, he made a case for keeping your Moms away from bookstores after she tried to mate with a Fabio cover.
論 (make a case for) + 文 (culture/ sentence)
= 論文 (essay)
an essay, like a senior thesis.
世 (society) + 論 (make a case for)
= 世論 (public opinion)
理 (reason) + 論 (make a case for)
= 理論 (theory)
theory, as in science or "theory vs. practice"
討 (attack/discuss) + 論 (make a case for)
= 討論 (discussion)
||make a case for
A PERSON has principles, but you TALK when you have discussion.