The plain, neutral "why": a request for the reason behind a thing, with no surprise attached. It pairs naturally with 因为 ("because") and 为了 ("in order to"), and it sits one shade apart from the puzzled 怎么 ("how come").
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字源zìyuánEtymology & Structure
字源洞见 zìyuán dòngjiàn · Etymological Insight
为 wèi (here in fourth tone) is the preposition "for, for the sake of", as in 为了 wèile ("in order to") and 为人民服务 ("serve the people"). The same character read wéi (second tone) means "to do, to act, to be". 什么 shénme is the ordinary word for "what", itself built from 什 (a vernacular "what") plus the question suffix 么.
Put together, 为什么 is literally "for what", that is, "for what reason", which is exactly how English "wherefore" and "what for" once worked. The logic is transparent: a cause is the thing an action is "for". The same 为 anchors a small cluster of reason-and-purpose words, 因为 yīnwèi (because), 为了 wèile (in order to), 因此 yīncǐ (therefore), so learning 为什么 opens the door to the whole family.
为什么wèishénmeAsking Why
为什么wèishénmewhy; for what reason
疑问代词 yíwèn dàicí
The neutral question word for cause. It asks plainly for the reason behind a fact, choice, or action, with no surprise or blame built in: 你为什么不喜欢他？("why don't you like him?"). It normally sits after the subject and before the verb, and the sentence otherwise keeps its ordinary order, since Mandarin does not front the question word.
A very common shape: 为什么 before a negated verb asks "why not". 为什么不 ("why not", general) and 为什么没 ("why didn't", about a past non-event) cover most cases. 为什么不试试呢？("why not give it a try?") can even be a gentle suggestion rather than a real question, softened by the final 呢.
你为什么不告诉我？
Nǐ wèishénme bù gàosu wǒ?
Why didn't you tell me?
用法yòngfǎPatterns — Asking and Answering
为什么 in use · the core patternsSubject + 为什么 + Verb , 你为什么走 · why are you leaving 为什么 + 不 / 没 + Verb , 为什么不去 · why not go Q: 为什么…？ A: 因为… , answer a why-question with 因为 (because) 因为…，所以… , because…, therefore… (full reason and result) 为了 + Goal , answer a purpose with 为了 (in order to)
因为 … 所以 …yīnwèi … suǒyǐ …because …, therefore …
The standard frame for answering 为什么. 因为 introduces the cause, 所以 the result, and Chinese is happy to keep both halves where English would drop one: 因为下雨，所以我没去 ("because it rained, [therefore] I didn't go"). In a direct answer you can lead with just 因为: Q 你为什么迟到？A 因为堵车 ("because of traffic").
因为我感冒了，所以今天没去上课。
Yīnwèi wǒ gǎnmào le, suǒyǐ jīntiān méi qù shàngkè.
Because I caught a cold, I didn't go to class today.
为了 + 目的wèile + goalin order to; for the sake of
When the real answer is a purpose rather than a cause, use 为了, not 因为. 为了 names the goal the action serves: 为了健康，他每天跑步 ("for the sake of health, he runs every day"). Asking specifically about purpose, you can use 为了什么 ("to what end"). The split mirrors English "because" (cause) versus "in order to" (purpose).
为什么 and 怎么 can both translate as "why", but they are not interchangeable. 为什么 wèishénme is the neutral request for a reason: 你为什么换工作？("why did you change jobs?"), simply asking the cause. 怎么 zěnme, used for "why", carries surprise or puzzlement, a "how come": 你怎么换工作了？("how come you changed jobs?", reacting to news that catches you off guard). If you want a flat, unloaded reason, choose 为什么; if you are also expressing that something is unexpected, 怎么 fits better. And remember that 怎么 alone can ask "how, in what way", a job 为什么 never does.
A second, finer split is reason versus purpose. 为什么 asks why in general and is answered by 因为 ("because"). When the question is really about a goal, 为了什么 ("for what purpose, to what end") is sharper, and the answer takes 为了 ("in order to") rather than 因为. 你为什么省钱？invites a cause ("because prices are rising"); 你省钱是为了什么？invites a goal ("to buy a house"). Keeping 因为 with cause and 为了 with purpose will make your answers land correctly.
成语chéngyǔSet Phrases
事出有因shì chū yǒu yīneverything happens for a reasonLiterally "when a matter arises, there is a cause", nothing comes out of nowhere. It is the quiet conviction behind every 为什么: ask the question and there will be a 因 (cause) to find. The 因 here is the same one in 因为 ("because").
前因后果qián yīn hòu guǒthe full cause and effectLiterally "the prior cause and the later result", the whole chain from why to what-happened. To know the 前因后果 is to understand a matter completely, from the reason a 为什么 seeks to the outcome it explains. 因 (cause) and 果 (effect, "fruit") are the two poles of explanation.
名正言顺míng zhèng yán shùnwith good reason and just causeLiterally "the name being right, the words follow smoothly", from the Analects: when things are correctly named, speech and action are justified. To act 名正言顺 is to have a sound, defensible reason, the kind of answer a 为什么 hopes to receive.
相关xiāngguānRelated
Related entries — pages and vocabulary in the neighbourhood of this one
怎么zěnmehow; how come因为yīnwèibecause所以suǒyǐtherefore; so为了wèilein order to; for什么shénmewhat原因yuányīnreason; cause
常见问题chángjiàn wèntíFrequently Asked Questions
What does 为什么 (wèishénme) mean?
为什么 wèishénme means 'why', a neutral request for the reason or cause of something: 你为什么学中文？('why are you studying Chinese?'). Literally it is 为 ('for') plus 什么 ('what'), 'for what', that is, 'for what reason'. It is the standard, tone-neutral way to ask why in both speech and writing.
How do you answer 为什么?
Most often with 因为 yīnwèi ('because'), which states the cause: 因为我喜欢中国文化 ('because I like Chinese culture'). To give a purpose rather than a cause, answer with 为了 wèile ('in order to'): 为了找工作 ('in order to find a job'). The pair 因为…所以… ('because… therefore…') gives a full reason-and-result answer.
Where does 为什么 go in a sentence?
为什么 usually comes after the subject and before the verb: 你为什么不来？('why aren't you coming?'). It can also open the sentence for emphasis: 为什么你不告诉我？('why didn't you tell me?'). Because Mandarin does not move the question word to the front the way English does, the rest of the sentence keeps its normal order.
What is the difference between 为什么 and 怎么?
为什么 wèishénme is a plain, neutral 'why', simply asking for a reason. 怎么 zěnme, when it means 'why', adds surprise, 'how come, how is it that': 你怎么不来？sounds puzzled or concerned, while 你为什么不来？just asks the reason. Also, only 怎么 can mean 'how / in what way' (怎么做, 'how to do it'); 为什么 only ever asks why.
What is the difference between 为什么 and 为了什么?
为什么 asks for the reason or cause behind something (why it is so). 为了什么 wèile shénme asks specifically for the purpose or goal ('for the sake of what / to what end'): 你这么努力是为了什么？('what are you working so hard for?'). 为什么 is answered by 因为 (because); 为了什么 is answered by 为了 (in order to).