Polite verb "vs" plain + n desu

[gerald_ford]

I just finished lesson 100 of the original beginner series and I have a burning question. To be polite, one can usually use the polite form of a verb: "tabemasu" not "taberu", or "ikimasu" not "iku".

But I've heard in Japan a lot, and now in lesson 100, that if you take a plain form verb and add "n desu" as in "taberun desu" or "ikun desu", that's polite too.

So what's the difference between just regular polite verb, and plain + "n desu"? Is one used in writing more than the other, or in conversation more? I think in my brief visits in Japan, the "n desu" form seems to be pretty common, but I am still unsure of when to use it, other than now I know it's polite.

Thanks all!

[toshimarise]

This is my understanding, but I'm just a student. The -masu form really is just polite; it doesn't change the meaning of the verb. But plain + n +desu changes the meaning a little. (And keep in mind plain +n + desu is used with adjectives a lot too, with pretty much the same meaning.)

First, it can add emphasis, (mostly with adjectives, actually) like "nihon ni ikitain desu" could be something like "I really want to go to Japan".

Or second, it indicates that you're offering your statement as a reason, explanation, or excuse. Like if you were late to meet someone, you might say "sumimasen, michi ni mayottan desu", "sorry, (it's because) I got lost". Or if you had to refuse an invitation to dinner, you might say, "ashita, shiken ga arun de, konya wa benkyou shite imasu", "tomorrow I have a test, (so) tonight I am studying". It really depends on the context of the conversation.

You can also use the "n" in plain + n +da conjugations, to use the "explanation" sense of the construction in casual/informal speech.

Does this answer your question?

[gerald_ford]

Ok, that confirms a few things, but I also noticed that people frequently ask as a question too. For example when I was last there, some asked me "nan nichi irun desu ka?" which means "how many days will you be here?".

Or in the dialog for lesson 100, one character says "gorufu taikai e wa ikun desu ka?" or "will you go the golf tournament?"

So it seems like it's often casual, but polite as well. Or am I missing something?

[Javizy]

Just so you know, desu can be used straight after a plain verb to convey essentially the same politeness level as masu. The difference seems to be stylistic, and sometimes a matter of convenience. If you are used to having plain conversations, which I'm sure most Japanese are, then you might need to tac on desu to avoid sounding rude after splurting something out. I've heard it added after about a 3-second pause many a time

toshi explained the use of 'no' pretty well. The answer to your question is in the fact that using 'no' implies shared information (usually seen or heard) between the speaker and listener, and if it doesn't, then it becomes emphatic because the speaker is acting as if it does. For example, if you see somebody and ask them what they're doing, it is almost unnatural not to use 'no'; likewise when the person answers the question. On the phone, however, you probably wouldn't, since you have no idea what they're doing. In your examples, you and the guy both knew you were there, and the two golfers knew there was a golf tournament.

Still, I'm no expert on this. There is a better explanation in A Dictionary of Basic Japanese Grammar by Seiichi Makino, which I recommend to consolidate all the grammar you learn in the beginner series (and beyond). Hope I helped clear things a little, anyway

[gerald_ford]

Thanks Javizy, that seems to match my experiences as well in Japan. I actually do own that grammar dictionary you mentioned, and it confirms much of what toshimarise said (thank you for your input), but what you said also confirms the fact that it seems somehow more casual and native sounding. My wife had once told me that, but I never quite understand the connotations until now. Constant use of polite verbs seems to sound kind of stiff when I talk to Japanese people, unless it's in a pretty formal meeting, but using straight informal talk isn't always advised, so the "n desu" construction seems like a happy compromise. Smooth and fluent, but still polite.

Thanks to you both!

[wiki168]

-masu kei is a polite form. it is used in normal situation.
-n desu express:
1- Wanna know something very strong.
rei: Miraa san wa kaigishitsu ni irun desu ka?
ミラーさん　は　かいぎしつに　いるんですか。

2- Asking for explaination.
rei: A: doushite, okuretan desu ka?
どうして　おくれたんですか。

3- Reason, Excuse.
rei: B: basu ga konakattan desu.
バスがこなかったんです。

4- Hesitation and seeking for more information.
rei: boutan o oshita noni, okane ga denain desu ga,...
ボタンを押したのに、おかねがでないんですが、。。。

5- equivalent to But
rei: kyou wa ikenain desu ga, ashita nara ikeru to omoimasu.
きょうは　いけないんですが、あしたなら　いけるとおもいます。

-n desu is usually used in spoken language not in writing.