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

Question

Good afternoon all,

From what I understand, special "suru" verbs only have one potential form which is formed using the syntax:

[verb-stem] + [せる]

For example, 愛す・愛する → 愛せる and 訳す・訳する → 訳せる.

However, A Dictionary of Advanced Japanese Grammar claims that "熱する (ねっする)" and "察する (さっする)" conjugates in the same way as "する". Snippet:

By that claim, it seems to mean that the potential form of "熱する" would be "熱できる (uh, ねっできる?)" and the potential form of "訳する" would be "訳できる".

WWWJDIC also has a chart which shows that the potential form of "訳する" is "訳しえる" and/or "訳しうる" (link).

So now we have these potential forms:

1. [verb-stem] + [せる] (e.g. 愛せる, 訳せる, 熱せる, 察せる)

2. [verb-stem] + [しえる] (e.g. 愛しえる, 訳しえる, 熱しえる, 察しえる)

3. [verb-stem] + [しうる] (e.g. 愛しうる, 訳しうる, 熱しうる, 察しうる)

4. [verb-stem] + [できる] (e.g. 愛できる, 訳できる, 熱できる, 察できる)

Are all of these 4 conjugations grammatically valid potential forms of special "suru" verbs?

Answer 1

As @fefe mentions, the 4th one is wrong for the examples you mention. I think your grammar book forgot about the potential.

I don't know the detailed etymology, but I guess somehow 愛する, 訳する, 熱する, 察する are more like "proper verbs" (although they inherit most of the irregularities of する), whereas 勉強する etc. are still more like a compound: noun+する, thereby inheriting also the suppleted potential of する, できる.

Answer 2

In order here.

1 These are valid words, but not valid する verb forms. That is to say the verbs in these cases are 訳す,　愛す, etc. In the case of some of these the す verb is much more commonly used than the する verb and can probably be considered the "correcter" version of the verb.

2 + 3 These are valid and in fact the exact same thing. They are both ～得る when written in kanji. An example word using this grammar form would be ありえない. For the exact difference between this and the common modern potential forms consult your grammar book.

4 できる is the correct potential form for most する verbs in modern Japanese. However it is not valid in the case of す verbs.　達できる, 熱できる, etc are wrong.

If you are in doubt about the correct potential form of one of these verbs use ～うる when writing since both する　and す verbs result in the same thing in these cases. When speaking use ことができる if you want to be safe.