Special status of 話せる as a verb

Question

I came across 話せる, as the potential form of 話す. However, 話せる can also be found in dictionaries as a verb on its own. It can even take inflections, and has its own potential form, 話せられる! I don't really understand what that could mean (to be able to be able to speak?).

In this question, it's presented as merely a form of 話す, along with other potential forms. But there I couldn't find a dictionary entry for 泳げる for example.

How come? Is it just a form that's important enough to have its own dictionary entry, or is it a separate verb? Is it because it has a second meaning (2. to be understanding; to be sensible​)?

Are there other verbs like this?

Answer 1

Yes, the dictionary breaks out this potential form exactly because it has a secondary meaning (which is derived from the generic potential).

Good monolingual dictionaries also do this. For example:

Sankoku

はな・せ る［話せる］｟自下一｠
①〈話／わけ〉が よくわかる。
「あの人は━」
②「話す」の可能形。

Daijirin

はな・せる[3] 【話せる】
（動サ下一）
〔「話す」の可能動詞形から〕
話し相手とするに足りる。ものわかりがよい。「うちの親父は━・せる」

Shinmeikai

はな・せる③ 【話せる】
（自下一）
〔「話す」の可能動詞形〕話や交渉の相手にする値うちがある。
「話せる〔=思いやりがあり人の気持をよく理解してくれる〕人」

Daijisen

はな・せる【話せる】
アクセント はなせ↓る
〘動サ下一〙《話すことができる意から》話し相手とするに足りる。物わかりがよい。話が わかる。「うちの校長は―・せる」

Meikyo

はな・せる【話せる】
①［自他下一］「話す」の可能形。
「英語 が／を話せる」
②［自下一］（①から）話し相手とするに足りる。ものわかりがよい。融通がきく。
「うちの親は話せる」

Nikkoku

はな・せる【話】
〘サ下一〙 （「はなす（話）」の可能動詞）
①話すことができる。
＊吾輩は猫である（1905−06）〈夏目漱石〉三
「話せないとすれば〈略〉切角の智識も無用の長物となる」
②話し相手とするに足りる。物わかりがよく融通がきく。
＊浄瑠璃・歌枕棣棠花合戦（1746）三
「コリャ咄せるぞ、面白い」

It also occurs for other potential forms that have gained a secondary meaning. Here are Sankoku entries for a few such verbs:

わら・える ［笑える］わらへる｟自下一｠
①自然に笑ってしまう。
「ひとりでに笑えてくる」
②おもしろおかしい。
「━話」
☞笑ける。

な・ける ［泣ける］｟自下一｠
〔泣くつもりでないのに、自然に〕泣いてしまう。
「じんと泣けてくる・━話だ」

い・える ［言える］いへる｟自下一｠
①〔俗〕そのとおりだ。
「たしかに それは━」
〔一九七四年に広まった ことば。「言えてる」の形は一九八〇年代に広まった〕
②「言う」の可能形。

It is natural that they would need to make a headword for the potential to be able to write the extra meaning somewhere.

However, as far as the weird auto-conjugation list in jisho goes, that's just junk. These potential-derived verbs are basically intransitive stative verbs, meaning they behave something similar to できる, which you can't add られる or させる to either. (Though, I think if you said 社長は話せられる it would borderline work as keigo, though it's an odd thing to say due to the mixing of formality levels.) It's basically just a semantic restriction that it's hard to stack potential/passive/etc on top of something already stative, especially when that state is something that is not easily changeable (like being a good conversation partner).

Answer 2

There is nothing really special about 話せる. I cannot answer why the dictionary you linked has a separate entry for it. It could be for the second definition, which is somewhat different from the normal potential sense.

In general, potential forms (e.g. 話せる), passive forms (e.g. 話される), and causative forms (e.g. 話させる) do have their own inflections. They all conjugate as ru-verbs (a.k.a. Group-II or ichidan verbs). You definitely need their ta-forms (話せた/話された/話させた) and te-forms (話せて/話されて/話させて) to express tense or aspect.

The potential form of a potential form/verb makes no sense for the very reason you thought 話せられる was strange. As a matter of fact, the following (order-sensitive) combinations are all invalid.

• potential-potential (x 話せられる)
• potential-passive (x 話せられる) [see this]
• potential-causative (x 話せさせる)
• passive-potential (x 話されられる)
• passive-passive (x 話されられる)
• passive-causative (x 話されさせる) [see this]
• causative-causative (x 話させさせる)

The causative-potential and causative-passive forms are identical. In the case of 話す, they are both 話させられる (the causative form being 話させる). This is a valid form and usually listed separately as causative-passive in conjugation tables. It has its own ta-form (話させられた) and te-form (話させられて).