theory

仮説、推測

何かが起きた理由や何が真実かについての、まだ証明されていない考え。

やさしい英語で： An idea about why something happened or what is true, which has not been proved.

• I have a theory about the noise.
• Her theory was that the dog had escaped.
• The police considered several theories about his disappearance.

使い方： a theory about something (Do you have a theory about the missing money?); a theory that… (My theory is that someone left the door open.)

類義語： idea, guess, hypothesis, conjecture

よく使う表現： my theory, one theory, theory about something

理論、学説

物事の仕組みや理由を説明する考えの体系で、通常は証拠に支えられる。

やさしい英語で： A set of ideas that explains how or why something happens, usually supported by evidence.

• This theory explains how stars form.
• New evidence supports the scientist's theory.
• Researchers tested several theories about the disease.

使い方： a theory of something (We discussed the theory of evolution in class.)

よく使う表現： scientific theory, theory of evolution, test a theory

理論

ある分野の土台となる規則や考え方を研究する学問。

やさしい英語で： A subject that studies the rules and ideas behind a particular kind of thing.

• She studies number theory.
• Our music theory course starts next week.
• Graph theory helps researchers understand networks.

よく使う表現： number theory, knot theory, music theory, set theory