noun, noun, used as a suffix
Refers to a systematic explanation, academic theory, or established doctrine. Often used as a suffix in compound terms like 進化説 (theory of evolution) or 地動説 (heliocentric theory).
彼は新しい経済説を発表した。
He presented a new economic theory.
地動説はコペルニクスによって提唱された。
The heliocentric theory was proposed by Copernicus.
noun
Used for a personal opinion or viewpoint, often in contexts like 自説 (one's own opinion) or 説を述べる (to state one's view).
会議で彼は自分の説を強く主張した。
He strongly asserted his opinion at the meeting.
この問題については様々な説がある。
There are various views on this issue.
noun
Refers to unverified talk or hearsay. Common in phrases like 説が立つ (a rumor spreads) or 説を流す (to spread a rumor).
彼が辞職するという説が流れている。
There's a rumor going around that he will resign.
それは単なる説に過ぎない。
That's just hearsay.