Can verbs/i-adjectives be indefinitely conjugated, or is there a limit?

Question

寒い can become 寒くない, which is apparently also an i-adjective. Can it be further conjugated to 寒くなくない?

What about 寒くなくなくない, and so on? Do Japanese speakers regard such expressions as outright ungrammatical or merely silly? (Silly as in, in English, multiple negations like "It's not the case that it's not the case that … it's cold" are silly but not ungrammatical.)

What about verbs? I know the causative-passive 食べさせられる (to be made to eat) is legit, but is there such a thing as, say, potential-causative-passive-potential? In English, "can be made to be able to eat" is perfectly grammatical and can be actually useful, as when discussing an anorexia patient. How would one say it in Japanese?

Is it grammatical to say 食べられさせられられる (食べる -> potential 食べるられる -> causative 食べられるさせる -> passive 食べられさせるられる -> potential, the final form 食べられさせられるられる — not sure if I did it right)?

I'm asking this mainly out of theoretical rather than practical interests, but I would also appreciate information about limits of conjugation in ordinary conversation.

Answer 1

Let's talk about something practical first. Something like 食べさせられたくなかったです, beautifully explained in this article, is probably the longest natural verb "form" that may appear in ordinary conversations.

Also, you don't need to worry about extremely long verbs conjugations. They usually do not stack as many times as the number of colors in the rainbow.

There are rules regarding the order of stacking conjugations. "Can be made to be able to eat" is 食べられるようにさせられうる, but this is not a conjugation of one verb.

Also, double-negation is a relatively common pattern in Japanese. 食べなくない, or more commonly 食べなくはない, means "I'm not saying I won't eat it" or "Admittedly I will eat it."

• What does ...なくはない mean?
• Double negation of an i-adjective

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Now, let's move on to something which I don't think is not impractical. If you don't mind sounding silly, it's indeed possible to stack many more conjugations and helping verbs for fun! 寒くなくなくなくなくなくない is perfectly valid as a wordplay, and children love something like this. Lyrics sometimes contain なくなくなくない. A more "sophisticated" version would be 寒くないわけではなからざらずんばあらざらじ (septuple-negative; children do not understand this).

When I was a middle school student, I joined all the humble expressions I knew and made the most humblestestest expression just for fun: 食べさせていただかせてもらわせられたてまつりつかまつりはべりおります (≒ "It's my pleasure to humbly appreciate that I am allowed to be honored to be delighted to eat it."). I believe this is "grammatical", but of course it's nothing more than a silly wordplay, and it would be simply rude if I used it in real business settings.