可能 vs 可以 (kěnéng vs kěyǐ): possibility vs permission
可能 (kěnéng) expresses epistemic possibility—whether something is likely or maybe true. 可以 (kěyǐ) expresses deontic permission or practical feasibility—whether someone is allowed or able to do something. They are not interchangeable: 可能 is about uncertainty, 可以 is about permission or capability.
The core distinction between 可能 and 可以 lies in the type of modality each expresses. 可能 (kěnéng) is an epistemic adverb or adjective that conveys possibility or probability (e.g., 'It might rain'). It is used when the speaker is uncertain about a fact or event. 可以 (kěyǐ) is a modal verb that primarily conveys deontic permission (e.g., 'You may leave') or practical feasibility (e.g., 'I can carry this'). While both can be translated as 'can/may' in English, 可能 is about likelihood, while 可以 is about authorization or capability.
When to use each
Use 可能 to express epistemic possibility, meaning that something is likely or might happen. It is often used as an adverb before the verb or as an adjective (e.g., '是可能的'). It cannot grant permission or indicate ability. Example: 他可能来了 (Tā kěnéng lái le) — 'He might have come.'
In formal contexts, 可能 can also be an adjective meaning 'possible' (e.g., '一个可能的结果'). Unlike 可以, it never appears in questions asking for permission.
Use 可以 to express permission (e.g., 'May I...?') or practical feasibility/ability in a given situation (e.g., 'I can swim' if conditions allow, but not a learned skill). It is a modal verb that precedes the main verb. Example: 我可以进来吗？(Wǒ kěyǐ jìnlái ma?) — 'May I come in?'
可以 can also indicate sufficiency or adequacy, e.g., 这个菜可以了 (Zhège cài kěyǐ le) — 'This dish is good enough.' In negative form (不可以), it forbids things, whereas 不可能 simply denies a possibility.
At a glance
| 可能 | 可以 | |
|---|---|---|
| Core meaning | Epistemic possibility (maybe, likely) | Deontic permission / practical feasibility (may, can) |
| Part of speech | Adverb (adjective as well) | Modal verb (precedes verb) |
| Used to ask for permission? | No | Yes |
| Negative form | 不可能 (bù kěnéng) — impossible | 不可以 (bù kěyǐ) — not allowed |
| Example in question | 可能吗？(Kěnéng ma?) — 'Is it possible?' | 可以吗？(Kěyǐ ma?) — 'May I?' |
Examples
- 可能明天可能下雨。Míngtiān kěnéng xià yǔ.It might rain tomorrow.Expresses a possibility, not permission.
- 可以你可以用我的笔。Nǐ kěyǐ yòng wǒ de bǐ.You may use my pen.Grants permission.
- 可能这件事可能很难。Zhè jiàn shì kěnéng hěn nán.This matter might be very difficult.Probability, not ability.
- 可以我可以帮你吗？Wǒ kěyǐ bāng nǐ ma?May I help you?Polite request for permission.
- 可能他可能知道答案。Tā kěnéng zhīdào dá'àn.He might know the answer.Uncertainty, not permission.
- 可以这里不可以抽烟。Zhèlǐ bù kěyǐ chōuyān.Smoking is not allowed here.Negative form indicates prohibition.
Common mistakes
- Using 可能 to ask for permission: '我可能进来吗？' — should use 可以.
- Using 可以 to express an uncertain possibility: '他可以来了' to mean 'He might have come' — should use 可能.
- Confusing the negative forms: 不可能 means 'impossible', while 不可以 means 'not allowed'.
- Using 可能 with a verb to indicate personal ability: '我可能游泳' (I can swim) — for ability use 会 or 能, not 可能.
FAQ
- When do I use 可能 vs 可以?
- Use 可能 when you want to say something is possible or probable (like 'maybe' or 'might'). Use 可以 when giving or asking for permission, or when saying that something is feasible under the circumstances. They represent two different types of 'can'.
- Can 可能 and 可以 be used interchangeably?
- No. They are not interchangeable. 可能 expresses possibility/uncertainty, while 可以 expresses permission or practical ability. For example, '他可能来' means 'He might come', but '他可以来' means 'He may come (is allowed to come)'.
- Is 可能 an adverb or an adjective?
- 可能 is primarily an adverb (e.g., 他可能去) but can also function as an adjective with the 是...的 structure (e.g., 这是可能的 'This is possible'). In contrast, 可以 is always a modal verb.
- What is the difference between 不能 and 不可以?
- 不能 expresses inability or 'cannot' (due to circumstances or lack of skill), while 不可以 expresses prohibition ('not allowed'). For example, '这里不能抽烟' means 'You can't smoke here (maybe because it's unhealthy)', but '这里不可以抽烟' means 'Smoking is forbidden here'.