雑談 and 議論: casual talk and discussion of an issue
Compare chatting before a meeting, an idea emerging during a break, and discussion of school rules. Time, conflict, and a conclusion do not alone determine the word.
Casual social talk
雑談 (ざつだん) means casual talk. 「会議の前に同僚と少し雑談した。」 describes briefly chatting with a coworker before the meeting.
In 「休憩中の雑談から面白い案が生まれた。」, an interesting idea emerged from conversation during a break. Casual talk is not defined by an inability to produce ideas.
Discussing an issue or proposal
議論 (ぎろん) means discussion or debate. 「新しい校則について生徒と教師が議論した。」 says students and teachers discussed the new school rules.
「感情的な議論を避け、まず事実を整理しよう。」 proposes avoiding an emotional argument and organizing the facts first. It does not report that the facts have already been organized.
Purpose rather than time alone
Being before a meeting does not make every utterance casual talk. Examine whether coworkers are chatting or participants are addressing an issue such as school rules.
議論 does not require a quarrel or an official meeting. The school-rule example identifies participants and a topic but does not state an agreement or final conclusion.
Which activity produces the idea in 「休憩中の雑談から面白い案が生まれた。」?
Show the answer and why
Casual talk during a break. The emergence of an idea does not replace 雑談 with an unstated formal discussion or agreement.