Can you do it? Maybe not, but it can be done.

This is a question I hear often and one that I had myself at one point.

What is the difference between the potential form and 「~ことができる」?

As you know, the potential form is a relative straight-forward verb conjugation indicating that one is able to do that verb. The only strange exception is 「する」 which becomes 「できる」, a completely different verb to indicate “one is able to do”.

The situation gets a little bit murkier when you normalize a verb with a generic event 「こと」 and use 「できる」 instead of just using the potential form. Ultimately, it seems like there’s two methods of expressing the potential. (Don’t complain, Chinese has… oh I don’t even know how many, there’s too many to count.)

The natural question for any learner of Japanese would be, “What’s the difference and when do I use one instead of the other?” Indeed, an excellent question! What’s even more confusing is when the original verb is 「する」 therefore becoming 「することができる」. Hey, isn’t that redundant??

It’s longer

The first and easy answer is, the 「~ことができる」 version is longer. Ha ha, aren’t you glad I’m here to clear everything up for you? Seriously though, the fact that you have another particle in there allows a lot more flexibility. Nobody says you have to use 「が」, that’s just a sentence pattern simplification.

Saburooさん, author of the 現代日本語文法概説, has some very excellent examples.

読むことしかできない – Can only read it.
読めしかしない – ????

Semantic Differences

Besides the obvious grammatical differences, what the original question is really asking is whether there’s any differences in meaning and usage. I would say the differences in nuance is so subtle, it’s debatable whether discussing them would even help learners of Japanese. The short answer is they are pretty much interchangeable and you can stop reading here.

For the rest of you who like to torture yourselves like me, let’s think about it for a second. 「~ことができる」 uses a generic event 「こと」 and a generic verb 「できる」 to say that the event is able to be done. Doesn’t it sound a bit… generic? In fact, I think using 「~ことができる」 makes it sound more like a general statement about feasibility.

電車で行けますか? – Can you go by train?
電車で行くことができますか? – Is it possible to go by train?

You can take this idea further to talk about general rules and policies.

タバコを吸うことはできますか? – Is smoking allowed (for anybody)?
タバコを吸ってもいいですか?- Is it ok to smoke? (I want to smoke.)
タバコは、吸えますか? – Able to smoke? (Are you asking if I can smoke? Otherwise, why are you asking me if you can smoke?)

In a similar vein, you can see examples of when you might want to use 「することができる」. It can sound a bit more formal since it addresses a larger audience than you personally. In fact, companies might decide to substitute even more former-sounding words such as 「可能」 in the place of 「できる」. You can’t do this with the regular potential form.

インターネットで登録することができます。- It is possible to register on the internet.
インターネットで登録することが可能です。- It is possible to register on the internet.
インターネットで登録できます。- You can register on the internet.


This is an example where not worrying about every little detail and just getting a lot of input might be the better approach. However, I think it is worth the time to examine what words are being used and what they mean by themselves (in this case 「こと」 and 「できる」).

I hope this short explanation can at least give you a general idea of the slight difference between the potential form and 「~ことができる」. As I mentioned, they are very similar and often interchangeable. My final suggestion is to keep things as simple as possible. For instance, don’t say 「することができる」 if you can help it. Why make things more complex than they need to be?

10 thoughts on “Can you do it? Maybe not, but it can be done.

  1. The way my Japanese lecturer explained it to me was that 〜ことができる had the nuance of being able to do something somewhere.

    ie. あのレソートでスキーすることが出来る

  2. hey Tae Kim this hasn’t got anything to do with your blog just wanted to say thankyou for taking the time to write the japanese grammar guide i would be no where without it ^_^ thanks man

  3. I think my Japanese teacher once said to us that ことができる is a bit more formal/polite than the potential form, which follows the ‘the longer it is, the more formal it is’ rule.

  4. Alright, related question…maybe I’m missing something obvious here, but…

    What does (for example) 出来ている mean? Does it have the same basic meaning as 出来る with a different nuance…? Like, “can do” vs. “can be doing” or something?

    If the meanings are relatively similar, I understand that I’m best off just seeing this sort of thing in context lots of times to see the difference, but I just want to make sure I’m not on the wrong track.

    Sorry to post on an older entry, but this seemed like an appropriate place.

    • A much later response than you’d prefer, I’m sure, but this is a good question.

      出来る is considered the potential form of する, but it has another meaning, slightly removed. This second meaning of “to be built, made, or completed” is the meaning you’re looking for here. If something is 出来ている, it’s ready, or finished, or prepared.

      I’ve never seen 出来ている used to indicate progressive possibility, I can’t think of any useful situations for such a form to exist, and if they did, they would likely use the -ていることが出来る method of construction for clarity anyway.

  5. My teacher is a native speaker, and she said you CAN use ことが出来る, but it’s still not fully accepted in Japanese. She said it sounds foreign so it places emphasis on what you’re saying.

    For example, 俺を倒すことはできない rather than just 俺を倒せない.

  6. My teacher said that ことができる rather shows “inner causality”, while “VBpotential” “external causality”.

    I cite from An Introduction to Japanese Grammar, Syntax and Verbs:
    “見られるmeans “being able to see (something) (at this moment)”. Similarly‚ 歩ける means “being able to walk (at this moment)”. In contrast‚ 見ることが出来るand 歩くことが出来る mean being able to see‚ or walk‚ in general.
    Particularly with negatives‚
    this difference is striking. For instance‚ a person whose glasses are so dirty they can’t really see any of the things we point out to them might say:
    “I can’t (really) see (it).”
    This is hardly anything to worry about as the potential form used is one associated with temporary impairment. However‚ if they had used:
    We would have good reason to apologize for telling them to look at something; they’re blind.”

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