理lǐ所suǒ当dāng然rán

Literal: by reason, it ought to be so
Figurative: Something so logical and expected that it is taken for granted; only natural, a matter of course.

Where does 理所当然 come from?

It comes from no particular story: it is a set phrase joining 理所 ("what reason dictates") with 当然 ("it must be so"), so that what logic demands is taken as a given. It is in very common use, especially in the press and in everyday speech. There is no reliable classical source that can be pointed to as its origin, so it is not attributed to any work.

How is 理所当然 used? Two examples

父fù母mǔ帮bāng了le你nǐ这zhè么me多duō，你nǐ却què觉jué得de理lǐ所suǒ当dāng然rán。
Your parents have helped you so much, yet you take it as a matter of course.
努nǔ力lì工gōng作zuò就jiù该gāi拿ná到dào报bào酬chou，这zhè是shì理lǐ所suǒ当dāng然rán的de事shì。
Whoever works hard should get paid; that is only right.

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