Japanese Sentences with Must and verb negatives
looking for some clarification with this sentence (from memrise)

あなたはくうこうであなたのぱすぽーとをみせなくてはいけません

memrise lists with meaning "you have to show your passport in the airport"
with a literal translation as "youは airportで passportを show must"

to me it reads (literally) as

you は airport で you の passport を not show は must not do

am i getting this right that "must" in Japanese (at least in this case) uses double negative with two negative forms of verbsThinking about some more

what does いけません ( and by extension いける or are they unrelated?) mean as a concept,
and why the japanese negative (~ません） form for the english positive (Must) form?

In english I could write "you must not not show your passport at the airport" or "you mustn't not show your passport at the airport" however the nots cancel each other out. which is how the Japanese seems to work to me.

putting it the other way what would
”あなたはくうこうであなたのぱすぽーとをみせてはいけます”
mean (swapping the negative to positive forms?) assuming it means anything
or other positive/negative combinations
”あなたはくうこうであなたのぱすぽーとをみせなくてはいけます”
and
”あなたはくうこうであなたのぱすぽーとをみせてはいけません”

and how would you say
"you must not show your passport at the airport"

Question

Japanese Sentences with Must and verb negatives
looking for some clarification with this sentence (from memrise)

あなたはくうこうであなたのぱすぽーとをみせなくてはいけません

memrise lists with meaning "you have to show your passport in the airport"
with a literal translation as "youは airportで passportを show must"

to me it reads (literally) as

you は airport で you の passport を not show は must not do

am i getting this right that "must" in Japanese (at least in this case) uses double negative with two negative forms of verbsThinking about some more

what does いけません ( and by extension いける or are they unrelated?) mean as a concept, 
and why the japanese negative (~ません） form  for the english positive (Must) form?

In english I could write "you must not not show your passport at the airport" or "you mustn't not show your passport at the airport" however the nots cancel each other out. which is how the Japanese seems  to work to me.

putting it the other way what would
”あなたはくうこうであなたのぱすぽーとをみせてはいけます”
mean (swapping the negative to positive forms?) assuming it means anything  
or other positive/negative combinations
”あなたはくうこうであなたのぱすぽーとをみせなくてはいけます”
and
”あなたはくうこうであなたのぱすぽーとをみせてはいけません”

and how would you say 
"you must not show your passport at the airport"

Answer

I saw this makes many learners confuse. 
The translation of "must / have to (affirmative sentence)" is ~なくてはいけません, it isn't negative in English though it sounds negative. You should accept it and I think to memoraize it with its translation would be better. 
It's like "if you don't do … (もしあなたが…をしないなら), it wont't be good (よくないです)" --> you must / have to do ... (...しなければいけません).

*you は airport で you の passport を not show は must not do --> (in Japanese) あなたがくうこうでパスポートをみせないのは、してはいけないことです。(We often omit "you / your" because everyone knows who does that and whose it is.

I hope this was helpful without confusing you more.

Answer

I think, MUST is a really strong word.
And there is no word that is equivalent in Japanese.
That is why we use double negative instead.

Answers · 4

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