The passive, the potential, and the potential-passive

[thegooseking]

みんなさん、こんにちは。

I am trying to get the passive and the potential right in my head. We can talk about Yodan and irregulars later, but for now, let's focus on Ichidan verbs.

For most Ichidan verbs (all except 見る, I think), the potential ("can do"), the passive ("is done") and the potential passive ("can be done") all attach られる to the stem - in other words, the verb form for all three is identical. So I'm guessing they're distinguished by particles, but I'm confused.

私は肉を食べられます。
I can eat meat. (Eating meat is something I can do.)

私は肉が食べられます。
For me, meat can be eaten. (For vegetarians, meat cannot be eaten, but I'm not one of them. (I used to be, but no longer am. ごめんね！))

肉は食べられます。
Meat can be eaten. (Not just for me; what I'm saying is meat is edible.)

But then isn't this also the affirmative passive, meaning "meat is eaten"? Is the distinction just determined by context, or have I got something wrong?

I know I've kind of shied away from using the [plain verb]+ことができる construction for the potential here. The truth is I'm not entirely clear on the difference between 私は肉を食べられます and 私は肉を食べることができます, either.

ありがとうございます。

小狼

[mmmason8967]

From reading your other posts I can tell you're well above my level. Nevertheless I'd like to have a go at answering...

私は肉を食べられます。
I can eat meat. (Eating meat is something I can do.)

I agree. This sentence uses を so it's not passive and therefore must be potential.

私は肉が食べられます。
For me, meat can be eaten. (For vegetarians, meat cannot be eaten, but I'm not one of them. (I used to be, but no longer am. ごめんね！))

I disagree. This sentence uses が so it's passive: As for me, meat is/will be eaten.

肉は食べられます。
Meat can be eaten. (Not just for me; what I'm saying is meat is edible.)

I agree ... I think . Your translation has it both ways by being passive and potential, but it seems to me to be quite likely that that's what it means. If I had to choose just one, I'd go for potential: As for meat, I/you/he/she/they can eat it. However, if it was in the past tense (i.e. 「肉は食べられました。」), I think it'd be passive: As for the meat, it's been eaten.

But then isn't this also the affirmative passive, meaning "meat is eaten"? Is the distinction just determined by context, or have I got something wrong?

No, I think if you wanted to say "meat is eaten", you'd say 肉が, not 肉は. And since it does say 肉は, you're not trying to say "meat is eaten".

I know I've kind of shied away from using the [plain verb]+ことができる construction for the potential here. The truth is I'm not entirely clear on the difference between 私は肉を食べられます and 私は肉を食べることができます, either.

I really don't know--is there a difference?

マイケル

[Tracel]

Hi Guys,

I have done a bit of work on passives in Japanese and they are very complicated, especially with the particles. They are quite restricted in their uses as well. When spoken, the passive voice almost always has a negative connotation in meaning. In written work, it works more like the English passive.

The potential form can use several different particles to mark a direct object as well. In fact, it is most common to mark the direct object with が instead of を, and to mark the 'experiencer' with は. The first sentence below is most likely to be potential with no other clues, but not because of the object marker.

小狼さん wrote:私は肉を食べられます。
I can eat meat. (Eating meat is something I can do.)
The sentence:
私は肉が食べられます。
is also a very common way to say that "I can eat meat".

The particle をcan also be used in the 'indirect passive' sentence below:
私は姉に肉を食べられました。　
Meaning something like: I had my meat eaten on me by my sister. Or better English would be: My sister ate my meat (the rat). Or even: The meat was eaten by my sister, argh.

If you don't know who ate it, then you can take out the 姉に part, and you end up with
私は肉を食べられたよ。　Here context will tell you that the meat is gone, and by god, who ate it up on me!!!

My grammar book has a good set of examples to show some of the differences. I copied it out for you below:

The potential for of the GR. 2 verbs is the same form as the passive form rareru.　Potential, passive or honorific structures are identified through syntax and context. Examples:

[１]．先生は刺身が食べられる。（Potential)
　　Sensei wa sashimi ga taberareru.
　　（My teacher can eat sashimi。）
[２]．先生は刺身を食べられた。（（A). Honorific, (B）Potential、（C) Indirect passive)
　　Sensei wa sashimi o taberareta.
　　（A) My teacher ate sashimi.　（B) My teacher could eat sashimi.　（C) Someone ate the sashimi, and my teacher was unhappy.
[３]．先生は学生に刺身を食べられた。（Indirect Passive)
　　Sensei wa gakusei ni sashimi o taberareta.
　　（The teacher had (his) sashimi eaten by his students.)

The authors' comments:
As seen in [１], if the direct object is marked by ga, taberareru can only be interpreted as potential; if there is an agent marked by ni, however, taberareru expresses indirect passive, as seen in [3]. If there is no agent marked by ni and the direct object is marked by o, taberareru is ambiguous; it can be either honorific, potential, or indirect passive, as seen in [2].

Hope this helps you out. It is pretty confusing because the 'indirect passive' does not really exist in English, at least not in this format.

Ciao for now,
トラ

[Tracel]

Oops, I forgot to address the difference between　ことができる and　‐られる.

Basically my grammar book says that they mean the same thing. The only difference is with style; the ことができる one is longer and more formal, and you may see it in writing more, and the ‐られる one is more colloquial and used more when spoken. Personally, I like ことができる because I find it easier to form.

じゃあね。

[thegooseking]

マイケルさん、トラさん、

Thanks for your responses. I'm somewhat relieved to know that it is complicated, and it's not just me being dense

[１]．先生刺身が食べられる。（Potential)
　　Sensei wa sashimi ga taberareru.
　　（My teacher can eat sashimi。）

My grammar book has a similar example: お父さんは刺身が食べられません. It does translate this as "My father cannot eat sashimi", but then goes on to explain that it's literally, "As for my father, sashimi cannot be eaten." Seemingly indicating that it's both potential and passive. So I wonder if using が for the potential object is technically passive, even if we wouldn't translate that passive into English.

The point of that distinction is that I was trying to figure out how to generalise this without that "as for (whoever)". For example, どのきのこかが食べられません - Some mushrooms are inedible ("Some mushrooms cannot be eaten"). I would have chosen は, but because the topic is (implicitly) mushrooms as a general class, but the subject is only some mushrooms, I chose が. But I have no idea if I've got any of this right!

小狼

[Teabag]

Examples:

[１]．先生刺身が食べられる。（Potential)
　　Sensei wa sashimi ga taberareru.
　　（My teacher can eat sashimi。）

Tracelさん、
こんにちは。
これは完璧な説明だよね。
Tracelさんと一緒に日本語を勉強するのは「100万年の幸せ」だ。
「100万年の幸せ」という歌は先言ってた「ちびまる子ちゃん」のエンディングテーマなんだ。
このＭＶを見ると、ちびまる子ちゃんというアニメについてなんとなくわかりますよ。
聴いてみてください。すごい幸せっぽい歌なんです。Tracelさん好きな妖怪じゃない。Get ready!!
https://www.youtube.com/watch?v=BhQWtGagmGk&feature=player_detailpage

[mmmason8967]

My grammar book has a similar example: お父さんは刺身が食べられません. It does translate this as "My father cannot eat sashimi", but then goes on to explain that it's literally, "As for my father, sashimi cannot be eaten." Seemingly indicating that it's both potential and passive. So I wonder if using が for the potential object is technically passive, even if we wouldn't translate that passive into English.

That's an interesting point. Maybe there's a lot less difference between the passive and the potential than we think there is...

I found トラさん's examples very helpful. I'd like to summarise my understanding as it is now: this is me thinking aloud, so please feel free to criticise or mock as the feeling takes you!

Simple Passive
Take the active version of the sentence, make the direct object into the subject, and change the verb-ending:-

刺身を食べました。
Sashimi o tabemashita.
<somebody> ate the sashimi.
　⇓
刺身が食べられました。
Sashimi ga taberaremashita.
The sashimi was eaten <by somebody>.

Honorific
Take the active version of the sentence and make the verb-ending passive:-

先生が刺身を食べました。
Sensei ga sashimi o tabemashita.
The teacher ate the sashimi.
　⇓
先生が刺身を食べられました。
Sensei ga sashimi o taberaremashita.
The teacher ate the sashimi.

Indirect Passive
This is considerably more difficult. The first feature is the implication that whatever the sentence describes is somewhere between inconvenient and disastrous. The second, as トラさん says, is that the Indirect Passive doesn't really exist in English; in fact I suspect that the natural translation of an Indirect Passive sentence into English will always result in an active sentence. Take this deliberately unambiguous example:-

あの人は子供に死なれたんです。
Ano hito wa kodomo ni shiraneta ndesu.
That (poor) woman's child died, you know.

In this example 死ぬ is an intransitive verb, so I guess one sure sign of the Indirect Passive is an intransitive verb being made passive (I don't think you can make a Simple Passive with an intransitive verb). However, if the verb is transitive, it has to be other elements of the sentence that make it obvious we're dealing with the Indirect Passive. I think that these other elements are probably (a) there's likely to be an agent marked by に and (b) the topic of the sentence is the person who is adversely affected: this might be an explicit topic marked with は, or the speaker, or some other person understood from the existing context (although this third option won't apply to example sentences in textbooks).

Potential
This is the one that I find the most difficult. The only process I can think of is: if you can eliminate the other three possibilities, it has to be Potential.

先生は刺身を食べられる。
Sensei wa sashimi o taberareru.

If this was Simple Passive it would be sashimi ga, so we can eliminate that. I don't think that the Indirect Passive is too likely because the tense is non-past, indicating a habitual, repeated or future state--if you wanted to say that your teacher constantly has someone else eating his sashimi, surely you'd find a better way to say it? (And incidentally that makes me wonder whether another feature of the Indirect Passive might be that's it's usually going to be in the past tense).

However, you can't eliminate the Honorific so, in this case, you can't be sure whether it's Honorific or Potential. If the topic was somebody less honourable (e.g. watashi), then you could eliminate the Honorific and be pretty sure that the sentence was Potential.

先生は刺身が食べられる。
Sensei wa sashimi ga taberareru.

Because of the ga we can immediately eliminate the Honorific and Indirect Passive. That leaves the Simple Passive and the Potential. The topic sensei wa doesn't really seem to fit at all well if we try treating sashimi ga taberareru as Simple Passive, so I think we can eliminate the Simple Passive. The only thing that's left is the Potential.

　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　

Although the examples from トラさん's textbook were very helpful, I had difficulty with some of the author's comments:-

[１]．先生刺身が食べられる。（Potential)
　　Sensei wa sashimi ga taberareru.
　　（My teacher can eat sashimi.)
As seen in [１], if the direct object is marked by ga, taberareru can only be interpreted as potential;

This seems to be a petitio principii argument: if you assume that the sentence is potential, then sashimi is the direct object and is marked by ga but since that relies on the assumption that the sentence is potential, you can't go on to use it as evidence that the sentence is potential. Our problem is how to tell whether sashimi ga is the subject of a passive phrase or the direct object of a potential phrase.

[３]．先生は学生に刺身を食べられた。（Indirect Passive)
　　Sensei wa gakusei ni sashimi o taberareta.
　　（The teacher had (his) sashimi eaten by his students.)
...if there is an agent marked by ni, however, taberareru expresses indirect passive, as seen in [3].

You can also have an agent marked by ni in a Simple Passive sentence. To be fair, the author probably thinks it's really obvious that the sentence isn't Simple Passive.

マイケル

[thegooseking]

I think that's a really good analysis, マイケルさん. I don't have enough authority to vouch for its accuracy, but it certainly makes sense to me, and was very helpful

I do, however, question the last bit.

先生は刺身が食べられる。
Sensei wa sashimi ga taberareru.

Because of the ga we can immediately eliminate the Honorific and Indirect Passive. That leaves the Simple Passive and the Potential. The topic sensei wa doesn't really seem to fit at all well if we try treating sashimi ga taberareru as Simple Passive, so I think we can eliminate the Simple Passive. The only thing that's left is the Potential.

I'm with you as far as "that leaves the Simple Passive and the Potential", but I think you could stop there. I'd be inclined to think it's both. Now, the point I made in my last post is that we would probably translate this hybrid passive-potential as a simple potential (assuming we have an appropriate topic to become the subject). Semantically, I don't think there's much difference. So I would arrive at the same conclusion you did. But I can't help but feel that if we looked at more complex examples, the idea that there's a passive component in there might become important.

ありがとうございます！

小狼

[Tracel]

マイケルさんと小狼さん、こんにちは。

小狼さん wrote:
My grammar book has a similar example: お父さんは刺身が食べられません. It does translate this as "My father cannot eat sashimi", but then goes on to explain that it's literally, "As for my father, sashimi cannot be eaten." Seemingly indicating that it's both potential and passive. So I wonder if using が for the potential object is technically passive, even if we wouldn't translate that passive into English.

やっぱり、これは難しい話題ですよね。

I would agree with you except for a few points that don't make this theory work in Japanese at least.
(1) The English in the sentence below is clearly passive, but I think this is just to emphasize the topic element of wa. wa here is pointing out that 'as for my father' and not me or someone else, the fact is he cannot eat sushi. I have personally always hated this translation of the wa particle, because it becomes such clumsy English:

"As for my father, sashimi cannot be eaten."

(2) The passive form takes a clearly different form with the other types of verbs such as in the sentence below. I have kept all of the parts in the sentence for clarity, but if the 'wife' part were understood already, then it could be omitted.

原田さんは奥さんに高いコートを買われた。

The only real way to translate this in English nicely would be: "Mr. Harada's wife bought an expensive coat (and he was unhappy)." You could say "As for Mr. Harada, a coat was bought by his wife" but it is clunky.　So we have a passive construction becoming active in English like マイケルさん pointed out.

Now the potential for 買う is 買える and not 買われる.　So the following sentence is quite different:

原田さんは奥さんが高いコートを買えました。
"As for Mr. Harada, his wife could buy an expensive coat."
Here you could not delete the "wife" part without changing the meaning completely. Again, "as for Mr. Harada" is used but this is because we do not have a topic marker in English.

If this was Simple Passive it would be sashimi ga, so we can eliminate that. I don't think that the Indirect Passive is too likely because the tense is non-past, indicating a habitual, repeated or future state--if you wanted to say that your teacher constantly has someone else eating his sashimi, surely you'd find a better way to say it? (And incidentally that makes me wonder whether another feature of the Indirect Passive might be that's it's usually going to be in the past tense).

I don't know about the Indirect passive being only put in the past tense, but it does almost look like you are correct. Although I wonder if it is a rule. Consider this scenario. The professor is talking to someone and not paying attention to his sushi. Suddenly a crow starts eating the sushi so the professor's partner says:

あら先生、すしを食べられますよ。(カラスに）
Oh professor, your sushi is being eaten.　（By a crow).

I wonder if Natsuko-sensei would give her input on this topic. I am really making educated guesses here, so I don't know what the answer really is.

Good post by the way. This is a really difficult topic and I know I need a lot of practice to get it right. I am not even close as yet to being able to use the passive well in Japanese though.

Cheers,
トラ

[thegooseking]

トラセルさん,

やっぱり、これは難しい話題ですよね。

I would agree with you except for a few points that don't make this theory work in Japanese at least.
(1) The English in the sentence below is clearly passive, but I think this is just to emphasize the topic element of wa. wa here is pointing out that 'as for my father' and not me or someone else, the fact is he cannot eat sushi. I have personally always hated this translation of the wa particle, because it becomes such clumsy English:

"As for my father, sashimi cannot be eaten."

(2) The passive form takes a clearly different form with the other types of verbs such as in the sentence below. I have kept all of the parts in the sentence for clarity, but if the 'wife' part were understood already, then it could be omitted.

原田さんは奥さんに高いコートを買われた。

The only real way to translate this in English nicely would be: "Mr. Harada's wife bought an expensive coat (and he was unhappy)." You could say "As for Mr. Harada, a coat was bought by his wife" but it is clunky.　So we have a passive construction becoming active in English like マイケルさん pointed out.

Now the potential for 買う is 買える and not 買われる.　So the following sentence is quite different:

原田さんは奥さんが高いコートを買えました。
"As for Mr. Harada, his wife could buy an expensive coat."
Here you could not delete the "wife" part without changing the meaning completely. Again, "as for Mr. Harada" is used but this is because we do not have a topic marker in English.

Interestingly, my dictionary actually lists both 食べられる and 食べられない under their own entries, as opposed to just dismissing them as a form of 食べる. The definitions it gives are "edible" and "inedible" respectively. Presumably the meanings of "is eaten" and "can eat" and their negatives are relegated to forms of 食べる, but "edible" gets to be a dictionary verb in its own right.

Yes, "As for my father, sashimi cannot be eaten," is clumsy English, but it was never intended to be good English, anyway; it was intended to be a literal translation to explain the more natural English translation.

But, "My father finds sashimi inedible," is a perfectly good English sentence that, while not entirely passive, does retain the sense of edibility or otherwise being a property of the sashimi rather than the old man's capabilities. Perhaps it really is a property of the old man, but we don't want to blame him, so we blame the sashimi We understand that this means that my father cannot eat sashimi, but it has a bit of a different tone. It seems less... critical, maybe? It's not admitting that there's something he cannot do: it's the sashimi that can't be eaten by him!

I don't know that I'd say "my father finds sashimi inedible" is a terribly accurate translation of the original Japanese, but a large part of the difficulty in translating it is that 'inedible' is an adjective in English but a verb in Japanese. In that kind of situation, it'd be pretty impossible to come up with a literal translation that didn't sound clumsy!

小狼

[Tracel]

Teabagさん、

これは完璧な説明だよね。
Tracelさんと一緒に日本語を勉強するのは「100万年の幸せ」だ。
「100万年の幸せ」という歌は先言ってた「ちびまる子ちゃん」のエンディングテーマなんだ。
このＭＶを見ると、ちびまる子ちゃんというアニメについてなんとなくわかりますよ。
聴いてみてください。すごい幸せっぽい歌なんです。Tracelさん好きな妖怪じゃない。Get ready!!

Teabagさんは親切すぎますよ。 でも、私と一緒に日本語を勉強するのは好きだと言って、嬉しいですね。
「100万年の幸せ」という歌を聴きました。歌えている男の人の声が素敵ですね。私もいろいろなアニメとドラマの歌が好きですよ。でも、やっぱり時々暗くて変な歌だろうと思います。例えば、
Vampire Knight: https://www.youtube.com/watch?v=7q5EA8gOdaA
Yamato Nadeshiko Shichi Henge Drama: https://www.youtube.com/watch?v=-FZGtwY-jg8

トラ

[mmmason8967]

Oh, bother ... I replied earlier this morning but my message seems to have disappeared (or, more likely, I forgot to click the Submit button). So I'll try again...

I don't know about the Indirect passive being only put in the past tense, but it does almost look like you are correct. Although I wonder if it is a rule. Consider this scenario. The professor is talking to someone and not paying attention to his sushi. Suddenly a crow starts eating the sushi so the professor's partner says:

あら先生、すしを食べられますよ。(カラスに）
Oh professor, your sushi is being eaten.　（By a crow).

Oh, that's a good counter-example. Although I think the verb should be あら先生、カラスにすしを食べていられますよ。

It occurs to me that with the Indirect Passive it's not the verb that becomes passive, it's the entire phrase. So you start with an active phrase...

カラスがすしを食べる。

...make it into a passive phrase...

カラスにすしを食べられる。

...and it means "to be in a sushi-eaten-by-crows situation" or "to be on the receiving end of a sushi-eaten-by-crows situation". And since it's the entire phrase that's passive, the affected person is going to show up either as a は-marked topic or as the topic understood from context.

Also, if it's the phrase (and not the verb) that's being made passive, that would explain why you can use the passive form of intransitive verbs in Indirect Passive sentences.

マイケル

[thegooseking]

みんなさん、こんばんは。

A couple of ideas, here.

Firstly, I think intransitive verbs can be used with the simple passive, but マイケルさん is quite correct that they can't be directly made passive. What I think we have to do is take the noun-form of the verb (い-base with no ending), and then add が行われる (ga okonawareru). For example:-
泳ぎが行われます - swimming is done / swimming takes place
I guess this also works when a verb can have a direct object but doesn't.
食べが行われます - eating is done (without being specific about what's being eaten)

I'm a little out of my depth here, so I'd appreciate anybody coming along and telling me I'm wrong, but I guess the principle is that when we have a transitive verb, the direct object becomes the subject of the passive form of the verb, but when we have an intransitive verb, the verb itself becomes the subject of 行われる (which, incidentally, is the passive form of 行う).

--------------------------------------------------------------------------------------------------------------------------------------------------------------

Secondly, I thought it would be enlightening to look at examples of "can be done" other than 'edible'. I already knew about 見える ("visible") and 聞こえる ("audible"), but those are known to be exceptions, so won't really give any indication about how the rules work. Other examples I looked at were 'intelligible' and 'legible', which aren't Ichidan, so gave me some clues.

Firstly, 'intelligible' means "can be understood". 'To understand' in this sense is 理解する, and 'intelligible' is the plain potential form of that: 理解できる. Similarly, 'legible' means "can be read" and is 読める, the straight potential form of 読む.

So this seems to confirm that "can do" and "can be done" forms both use the same word for all types of verbs, not just Ichidan. So my guess is that the difference between "can do" and "can be done" is that the plain potential ("can do") keeps the same object as the original verb, but the "can be done", just like the simple passive, has the object become the subject.

So the state of my thinking right now is:-
この英語の本を読めます。 - I can read this English book.
この日本語の本が読めます。 - This Japanese book can be read (by someone who can read Japanese, which doesn't necessarily include me).
この日本語の本は読めます。 - This Japanese book can read

小狼

[Tracel]

小狼さん、

Firstly, I think intransitive verbs can be used with the simple passive, but マイケルさん is quite correct that they can't be directly made passive. What I think we have to do is take the noun-form of the verb (い-base with no ending), and then add が行われる (ga okonawareru). For example:-
泳ぎが行われます - swimming is done / swimming takes place
I guess this also works when a verb can have a direct object but doesn't.
食べが行われます - eating is done (without being specific about what's being eaten)

The noun formation for verbs is actually very different than in English. We can use the -ing form of the verb (gerund) to make a noun, but for most Japanese verbs you cannot use the base for verb by itself as a noun. You need to attach a nominalizer such as, -koto, or -no to the verb. For example:

ここで食べるのはだめですよ。
Eating here is not OK.

この池に泳ぐことは危険ですよ。
Swimming in this lake is dangerous.

ここから泳ぎのは可能性です。
Swimming from here is possible.

Secondly, I thought it would be enlightening to look at examples of "can be done" other than 'edible'. I already knew about 見える ("visible") and 聞こえる ("audible"), but those are known to be exceptions, so won't really give any indication about how the rules work. Other examples I looked at were 'intelligible' and 'legible', which aren't Ichidan, so gave me some clues.

Firstly, 'intelligible' means "can be understood". 'To understand' in this sense is 理解する, and 'intelligible' is the plain potential form of that: 理解できる. Similarly, 'legible' means "can be read" and is 読める, the straight potential form of 読む.

So this seems to confirm that "can do" and "can be done" forms both use the same word for all types of verbs, not just Ichidan. So my guess is that the difference between "can do" and "can be done" is that the plain potential ("can do") keeps the same object as the original verb, but the "can be done", just like the simple passive, has the object become the subject.

So the state of my thinking right now is:-
この英語の本を読めます。 - I can read this English book.
この日本語の本が読めます。 - This Japanese book can be read (by someone who can read Japanese, which doesn't necessarily include me).
この日本語の本は読めます。 - This Japanese book can read

Ha ha. . Nowadays I wouldn't be surprised if a book could read. So, your first example is unambiguous because you used を and the verb is clearly the potential form. The second example is ambiguous because you can use が and を to indicate the object marker for most potential verbs except できる、which uses が only from what I understand. So this sentence could mean - "I can read this Japanese book." Now, the third sentence I am not sure about because of the topic marker は. It could mean what you say . If we want to make sure that we get the meaning "This book is readable" then we would have to use a different format. My book suggests another auxiliary verb meaning can, or -able: (得る)　pronounced 「うる」 or 「える」.

この本は読み得ます。
Kono hon wa yomi emasu.
This book is readable.

I think we are getting into quite a quagmire of grammar here. One thing to keep in mind though is that, more often than not, Japanese grammar works really differently from English grammar. Even though you MAY be able to say something using the grammar pieces, doesn't mean that they would ever say it that way. I am hoping that 奈津子先生　will help us out with this post at some point. She usually has some really amazing insights.

トラ

[thegooseking]

トラセルさん、

The noun formation for verbs is actually very different than in English. We can use the -ing form of the verb (gerund) to make a noun, but for most Japanese verbs you cannot use the base for verb by itself as a noun. You need to attach a nominalizer such as, -koto, or -no to the verb. For example:

ここで食べるのはだめですよ。
Eating here is not OK.

この池に泳ぐことは危険ですよ。
Swimming in this lake is dangerous.

ここから泳ぎのは可能性です。
Swimming from here is possible.

Ah, I see. I did wonder. My grammar book calls the い-base the "noun-forming base" and uses examples like 話 and はじめ to illustrate forming nouns using just the base, but it doesn't really explain whether that's an across-the-board thing or just in a few cases. (Actually, it doesn't say very much about it at all.) It sounds like you're saying it's the latter.

My book does describe こと and の in a different section, though. The way it distinguishes them seems to be like こと refers to 'intangible' things or 'concepts' of verbs, while の refers to 'tangible' things (in this respect, の seems related to もの, but this is another of my wild theories ). So I guess 泳ぐこと would be talking about swimming in general, but 泳ぐの might be talking about a particular instance of swimming?

(Actually, another site I went to suggested that こと must be used rather than の to talk about ability to do something, but it might have meant specifically with the verb できる. It wasn't very clear.)

Ha ha. . Nowadays I wouldn't be surprised if a book could read. So, your first example is unambiguous because you used を and the verb is clearly the potential form. The second example is ambiguous because you can use が and を to indicate the object marker for most potential verbs except できる、which uses が only from what I understand.

Well, I don't think we disagree on this really, but I'm currently sticking with the (wild) theory that that's because there isn't much difference in sense between "X can do Y" and "X [topic] Y can be done". So I agree that you're right, the second example could be interpreted as "I can read this Japanese book" because the sentence doesn't have a topic, so the topic could quite reasonably be inferred as "me". If that's the case, then maybe the third example could mean "This Japanese book can be read."

(By the way, my book agrees with you that できる always changes を into が. My understanding was that the 'exceptionals' 見える and 聞こえる always take が as well, but I could be wrong about that.)

If we want to make sure that we get the meaning "This book is readable" then we would have to use a different format. My book suggests another auxiliary verb meaning can, or -able: (得る)　pronounced 「うる」 or 「える」.

この本は読み得ます。
Kono hon wa yomi emasu.
This book is readable.

I'm not sure I get this, to be honest. Doesn't this just suffer from the same ambiguity as the potential form of the verb? Actually, I wouldn't be surprised if they're related. My book doesn't cover it, but I can see a sort of morphological relationship between [い-form]+える and [え form]+る. Oops, wild theory alert! (By the way, the primary meaning of 得る is "earn, gain, obtain, get" - I did eventually find a dictionary that lists the usage you're referring to, but it was the third one I checked, so I wonder how common it is. Edit: Oh, I see there is a lesson on this very subject.)

小狼