I'm trying to understand how to conjugate verbs like 「発する」, 「属する」, 「察する」 and the like.

In a book I found 「発せられる」, which I think is the potential form of 「発する」, but it doesn't seem to follow the usual rules, so I was wondering: how about causative, passive and other forms? Does it matter if the verb has a っ (はっする) or not (ぞくする)?

I tried checking online, but I found both 「発せられる」 and 「発できる」 as potential (and IME recognize both), but I won't even be sure about how to read the latter (はっできる? はつできる? IME recognize the former) so I'm kind at a loss here.


As this answer says, these "special suru-verbs" are tricky and unstable. They conjugate sometimes like a suru-verb and sometimes like a godan-verb. However, they never turn to dekiru-form like normal suru-verbs do. That is, we can say 運転できる or 勉強できる but not 属できる nor 発できる.

One workaround is to conjugate them as godan verbs (発せる, 属せる, 察せる). However, as the linked answer says, tendency to conjugate as a godan verb depends on the verb. Among these three, I think 属せる is completely fine, but I feel 察せる is less common, and 発せる is unnatural (although understandable). Likewise, I feel 属さない/属そう is fine but 発さない/発そう/察さない/察そう are unnatural if not wrong. This means 属す(る) is more godan-like and 発する is more suru-verb-like in my mind.

How about 発せられる? This looks as if there were an ichidan verb 発せる, but actually せられる is an archaic passive form (e.g., 罰せられる is "to be punished" and 熱せられる is "to be heated"). 発せられる has a passive meaning ("to be emitted"), but from my experience せられる rarely has a potential meaning.

Fortunately, there is one safe approach that works regardless of the type of the special suru-verb. Simply use することができる and say 発することができる, 属することができる and 察することができる! I think even native speakers often (unconsciously) take this approach when they are unsure.

Another approach is to use し得る and say 発し得る, etc., but this tends to mean "possibly ~" rather than "is able to ~", and sounds literary and stiff.

Related: What are the valid potential forms of special "suru" verbs?

  • If 「発せられる」 doesn't work since it's intransitive, what does it mean? I found it in a book, so I thought is was right, is that a typo or at least unusual? Also, since 「発せる」 sounds unnatural, is there a potential form without using 「ことができる」 and 「し得る」? – Mauro Jun 17 '20 at 8:27
  • How about 特使を発する (from 三省堂 スーパー大辞林)? Isn't that a transitive usage? – kandyman Jun 17 '20 at 8:42
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    Oh, sorry! 発する is tranaitive (光を発する = to emit light, 発せられた光 = emitted light)! I'll fix my answer later. – naruto Jun 17 '20 at 8:55
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    @kandyman 損する is short for 損をする and falls into the same category as 楽する described here. For this type of verb, I think we can say 楽できる, 損できる, etc. (well, 損できる "to be able to lose money" is semantically odd...) – naruto Jun 17 '20 at 13:27
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    @Mauro I don't know. Well, if you know whether you can say Xをする or not, that should work at least as a hint. – naruto Jun 18 '20 at 5:18

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