如何
Depending on
Structure
Noun + （の）+ 如何 + だ(2)。
(1) によって
(2) である
Explanation
いかん is a grammatical structure that originates from the adverb 如何に, which means 'in what way' or 'how'. For almost all intents and purposes, it can be understood to mean 'depending on'. When used in the middle of a sentence to connect clauses, it is followed by the conjunctive form で, and when used to end a sentence, it is followed by the auxiliary verb だ.
いかん is always preceded by a noun, sometimes with the particle の in between.
- テストの成績のいかんで、奨学金がもらえるかどうかが決まる。My eligibility for the scholarship depends on my test results.
- 明日の天気いかんで旅行に行くかどうか決めよう。Let's decide whether or not to go on the trip depending on tomorrow's weather.
- プロジェクトが成功するかは、みんなの協力のいかんだ。Whether the project succeeds or not depends on everyone's cooperation.
- ボーナスが出るかどうかは、今月の売り上げいかんだ。Whether or not we get a bonus depends on this month's sales.
On some occasions, いかん may be followed by によって. Although adding によって might appear redundant, it actually serves to emphasize the 'depending on' nuance. A literal interpretation would be 'by means of depending on how (A) is, (B) will happen'.
- 会議の結果いかんによっては、計画を大きく変更する必要があるかもしれない。Depending on the outcome of the meeting, we might have to significantly change our plans.
In function, いかん is very similar to 次第, which also means 'depending on (A)'. It highlights that the result of an entire situation is contingent on the state or condition of (A). Because of this, it is frequently followed by phrases that contain verbs of determination, such as 決まる.
Fun Fact
It's interesting to note that いかん, like いかに, is related to どう ('how'). They all share the same kanji origin: 如何, 如何. Furthermore, many Japanese dictionaries and textbooks explain the meaning of いかん by using the phrase かどうであるによって, which translates to 'depending on in what way'. Therefore, it can be helpful to think of いかん as a more formal or literary equivalent of どう or かどうである.
Examples
明日の天気如何で、ハイキングは中止になるかもしれない。
Depending on tomorrow's weather, the hike might be canceled.
この取引が成立するかどうかは、先方の出方如何による。
Whether or not this deal goes through depends on the other party's next move.
調査結果の如何によっては、製品のリコールも視野に入れなければならない。
Depending on the results of the investigation, we must also consider a product recall.
「奨学金が受けられるか否かは、面接での評価如何です。」
'Whether or not you can receive the scholarship depends on your evaluation during the interview.'
今後の彼の態度如何では、彼を許してあげてもいい。
Depending on his attitude from now on, I might be able to forgive him.
新しいプロジェクトへの参加は、その条件如何によって考えたい。
I would like to consider participating in the new project depending on its terms and conditions.
被害者との交渉の如何で、示談金の額が変わってくる。
The amount of the settlement money will change depending on the negotiations with the victim.
試合の勝敗は、最後のワンプレー如何によるだろう。
The outcome of the match will likely depend on the final play.
店員からお客様へ：「商品の在庫状況如何によっては、お届けまでに時間がかかる場合がございます。」
Clerk to a customer: 'Depending on product availability, it may take some extra time for your item to be delivered.'
会社のウェブサイト：「弊社への投資をなさるかどうかの最終判断は、お客様ご自身のご判断如何によるものです。」
Company Website: 'The final decision on whether to invest in our company is one that depends on the customer's own judgment.'
国民の反応如何では、政府は法案を撤回せざるを得なくなるだろう。
Depending on the public's reaction, the government will likely have no choice but to withdraw the bill.
この歴史的建造物が保存されるかどうかは、市の決定如何である。
Whether or not this historical building will be preserved depends on the city's decision.