How do you conjugate i- and na- adjectives (into the presumptive, imperative, conditional, provisional, and progressive forms)?

Question

I feel like mastering conjugations is a major contributor to self expression in Japanese. I realized that some of the grammar points I have been working on have taught me new conjugations.

Usually its just a matter of explanation. I am wondering how to turn adjectives into the above listed forms of non-past, past, non-past negative, and the negative. (Provision, conditional, presumptive, imperative, progressive.) In the case of progressive I am only curious about na- adjectives and nouns. What should I do with da?

Answer 1

Adjectives (both 形容詞 (a.k.a. -i adjectives) and 形容動詞 (a.k.a. -na adjectives)) do not have the same sort of conjugational forms as verbs do, but I'll do my best to give you an equivalent of the verb forms to which you're referring. They often just borrow from other verbs (mostly だ) when appropriate.

I'll use 深い (deep) and 深刻な (deep, serious) as my examples, in order to make this a deep and serious explanation (har har).

Presumptive

I assume you mean the conjugation which is also often called "volitional;" e.g. 読もう for 読む. In this case, you'd get this:

深い　→　深いだろう　（The conjugation 「深かろう」 existed in old Japanese but nowadays I think you'd only see it in literature/manga.)

深刻　→　深刻だろう

Imperative

If you're implying a change in state, a lot of times you might see 〜なる used for imperatives here. My examples (which don't make any sense in the imperative mood, but for the sake of grammatical illustration) would be like so:

深い　→　深くなれ

深刻　→　深刻になれ

I don't think this would be too common, though. It sounds like it would be awkward for most usages. Most of the time some other roundabout construction would replace this.

Also, technically, 「深刻であれ」 would be the grammatical imperative of 「深刻だ」, but it sounds incredibly awkward.

Another way to say it which does not imply a change of state would be as follows:

深い　→　深くしろ

深刻　→　深刻にしろ

This means "be deep/serious" rather than "become" deep/serious.

Conditional

I'll assume you mean the "〜ら form" when you say "conditional," and the "〜ば" form when you say "provisional."

〜ら form:

深い　→　深かったら

深刻　→　深刻だったら

These are common.

Provisional

〜ば form:

深い　→　深ければ

深刻　→　深刻であれば、深刻なら (the latter is more common)

These are common.

Progressive

This isn't really something you'd normally use--a progressive form of an adjective is a bit strange, wouldn't you say? The normal present tense should do fine in most contexts. In most of the examples I can think of where we'd use an equivalent of the present progressive of an adjective in English (something like "he's being stupid"), Japanese would use an entirely different construction (「彼はとぼけている」 or something).

Hope this helps. For more information and lots of charts, just read Wikipedia's page on Japanese conjugations.