聞かす vs The Causative Form of 聞く (and what about 聞かさせる???)

Question

I was reading Naruto and came across the word 聞かされた. I understood its meaning, but soon got confused when tried to go about its conjugation. And thus I came across these...

寝る・寝かす

聞く・聞かす

待つ・待たす

散る・散らす

動く・動かす

冷える・冷やす／冷やかす (there are both???)

冷める・冷ます

I understand that all these verbs ended in ーあす are 他動詞... Theres quite a pattern here. The same goes for their meaning, which are resemble (if not are the same) as the causative form. For example:

寝かす - Cause someone to sleep, or put someone to sleep.

聞かす - Cause someone to listen, or let/make someone listen.

待たす - Cause someone to wait, or make/let someone wait.

動かす - Cause someone to move, or put someone in movement.

etc...

However, how are these ーあす verbs any different of the actual causative ーあせる verbs?

What is the difference between:

寝かす・寝かせる

聞かす・聞かせる

待たす・待たせる

散らす・散らせる

Furthermore, if these ーあす verbs are considered "verbs by itself", the do they have a causative form? Can I say 聞かさせる or 待たさせる???

I have read some other similar posts, but they just got me even more confused. So I decided to try my own question and hope someone can help me with this. Thanks in advance. ????

Answer 1

After some more research, I have come across some interesting explanations. I'll link below the 2 webpages that helped me the most.

https://forum.wordreference.com/threads/difference-between-su-ending-verb-and-causative.3239414/

https://maggiesensei.com/2009/10/24/%E3%81%95%E3%81%9B%E3%82%8B%E3%81%95%E3%81%9B%E3%82%89%E3%82%8C%E3%82%8B-saserusaserareru/

Well, what I came to understand is that there are actually 2 types of Causative Form: the one from Classical Japanese, and the other one from Modern Japanese.

In Classical Japanese, the causative is formed by adding す／さす to the 未然形 of the verb

if the 未然形 ends in /a/, add す: 行く=>いか＋す＝行かす

if the 未然形 ends not in /a/, add さす: 見る=>み＋さす＝見さす

The resulting verb conjugates in 下二段, i.e.

行かせ(ず)・行かせ(たり)・行かす(。)・行かする(とき)・行かすれ(ども)・行かせよ(！)

見させ(ず)・見させ(たり)・見さす(。)・見さする(とき)・見さすれ(ども)・見させよ(！)

And the causative of the verb す(equivalent of する) is often abbreviated: せさす=>さす

So I understood that all the verbs I listed before (and called ーあす verbs) are actually causatives derived from this Classical Causative. Since we are in the Modern Japanese era, they are now considered almost "verbs by itself" and not a causative per se, that's what I got from the post in Maggie Sensei's website.

In this same post, I understood that although verbs per se, they are still causatives, hence, to conjugate 聞かす in the causative as 聞かさせる is redundant and grammaticaly incorrect.

Therefore, the verb 聞く has, sort to say, 2 causatives... 聞かす (classical) and 聞かせる (modern). Is there any difference between them?

From the post of Maggie-sensei, what I understood is that:

YES, there is.

The modern causative form of 聞く is 聞かせる and it can mean both "To make someone listen" or "To let someone listen" and that depends pretty much on the context.

However, 聞かす (classical) has only one meaning, and that is "To make someone listen".

Because of this, I feel there is a tendency on using the classical causative with the Passive-Causative, because it is easier to the tongue...

聞く plain verb

聞かす(classical) ・・・ 聞かされる (passive-causative, more common).

聞かせる (modern) ・・・ 聞かせられる (passive-causative, less common).

TL:DR

聞かす　＝　聞かせる
The former is classical causative, the latter is modern causative.
But 聞かす only means "to make someone listen", while 聞かせる can also mean "to let someone listen".