In what way is the negative form of a verb an adjective?


I was reading the [wikipedia page on
"predicate,"](http://en.wikipedia.org/wiki/Predicate_%28grammar%29) where it
mentioned that in Japanese, the negative form of a verb is an adjective. I
thought that this was too expansive a statement to be true, but what does the
writer mean? Does the writer mean that only verbs in the ない form of the
negative are adjectives? Is this still too broad in meaning to be true?




Arguing about whether certain words "are" something or other is missing the
point in this context, I think. We do not classify words based on some innate,
a priori nature that we discern within them. We classify them based on
_behaviour_. And there is no a priori set of standards for that classification
either: we have to choose our own. It's completely arbitrary. But if we aim to
be scientific, we will generally want to choose standards that are as simple
as possible while explaining as much as possible (with as few inconsistencies
and exceptions as possible).

So, take the polite nonpast negative ending -nai. It ends in -i, like an
adjective. It takes endings like -katta and -kereba like an adjective. It can
be used adnominally or conclusively, like an adjective ("shiranai hito" vs
"ano hito wa shiranai"). Particles like "kedo" and "shi" attach to it like an
adjective. (Both of these last two points apply to verbs too, of course.) On
the other hand it can't be passivised like a verb.

In short, we can list many ways in which it acts like an adjective, and many
ways in which it doesn't act like a verb. On that basis, we might decide that
it is simpler to just call it an adjective than a verb-in-disguise. We would
advance a theory in which we have a category called "adjective" that includes
words like "akai", "hiroi", "kanashii" but also "ikanai" and "shiranai".

On the other hand, objections can be raised. In this thread, Ian has raised
some. I find them unconvincing (for the reasons given in dainichi's comments),
but we can find other differences. For example, the "-ide" ending does not
seem to be available to "natural adjectives": we can say "ikanaide" but not
"akaide" or even "akakunaide". So we have to adjust our theory to account for
this. Maybe we say "There are two kinds of adjectives, one natural and one
derived from verbs via the -nai ending; they behave very similarly but we
observe these differences..." Or maybe we say "Verbs in the negative nonpast
remain verbs; they exhibit some very adjectivelike behaviour but we can tell
the difference because..." We have to decide which theory fits the facts best,
ideally in the sense of "best" described above (simplest, most powerful, etc.)

Now, all of the above said, let's look at the -masen ending. It doesn't seem
to behave much like an adjective at all, except in very trivial ways So even
if we define our category of "adjective" such that it includes words with the
-nai ending, we probably won't put words with the -masen ending in there too.
We _could_ \-- it's arbitrary! -- but doing so wouldn't help us explain very
much. It would just make our theory more complicated. So, we don't.

Thus, what I think the wiki editor whose description you read meant was "
**once the plain nonpast negative ending -nai is attached to a verb, the
resulting word behaves so much like an adjective that it makes more sense to
classify it as one (in the classification scheme I am implicitly adopting).**
" Not "any negative verb phrase is an adjective by definition," or anything
extreme like that.

===

Dainichi's comment on your question is another example of the principle that
we are free to set up our categories in any way we like. Adjectives and verbs
are obviously different in many ways, but there is also a sense in which they
are similar. Given the structure "Hana wa X", a verb like "saku" could fit in
there, or an adjective like "akai". They fit into the same "slot" like that.
This isn't true of English; we can say "the flower blooms" but not "the flower
red"; we have to say "the flower _is_ red" (and, incidentally, for this reason
most linguists working on English will recognize a category that contains both
"blooms" and "is red").

So in _that_ high-level sense, Japanese adjectives and verbs form a unified
superclass of words, one that can be distinguished easily from, say, nouns, or
particles. That isn't any less true just because we can subdivide that
superclass into "verbs" and "adjectives" based on morphology. There might be
cases where using this superclass makes things easier for us (e.g. looking at
high-level syntactic patterns), and there might be cases where it's easier to
keep verbs and adjectives distinct (e.g. looking at word endings). Neither
analysis is wrong; they're just different tools for different tasks.

