想当然耳 — “To make subjective assumptions”

Q: What is the Chinese definition of 想当然耳?

耳：而已，罢了。凭主观推断，应该是这样

想当然耳 is a Chinese idiom (chengyu) meaning “to make subjective assumptions”. To take for granted without sufficient basis; to jump to conclusions based on personal inference. Literally, “Assume it to be so, that's all”.

Frequency

想当然耳 Pronunciation and Pinyin

想当然耳 Character Breakdown

Stroke Order

Character	Pinyin	Strokes	Meaning
想	xiǎng	13	think, miss, want
当	dāng	6	to act as or serve as
然	rán	12	thus, so, yes
耳	ěr	6	ear, hearing, handle, only

Example Sentence with 想当然耳

你不能总是凭着自己的一点经验就想当然耳地认为事情一定会成功，还需要做足充分的准备。

You cannot always assume things will naturally succeed based on a little bit of your own experience; you still need to make thorough preparations.

Origin and Story of 想当然耳

In 203 AD, Cao Cao, along with his son Cao Pi, led their army to capture Ye City, the stronghold of Yuan Shao. The 18-year-old Cao Pi, upon seeing Yuan Shang's 23-year-old wife Zhen Shi, who was exceptionally beautiful, forcibly took her as his own wife.

When Kong Rong learned of this, he wrote a letter to Cao Cao, citing an anecdote from history: King Wu of Zhou had bestowed Daji, the favorite concubine of King Zhou of Shang, upon Duke of Zhou.

Cao Cao was puzzled by this reference. Kong Rong then explained that he was simply inferring the past based on the present. This was a sarcastic remark by Kong Rong, implying that Cao Cao and Cao Pi's actions were as arbitrary and unfounded as this fabricated historical event, thus illustrating the meaning of "to assume things without basis" or "to take for granted".