う・よう + ではないかLet's do something, Why don't we

ようではないか is a construction that will primarily be used for making suggestions for mutual activities. This is a combination of either of the auxiliary verbs う or よう, ではない, and the sentence-ending particle, か. う and よう primarily express will or intent like 'shall' in English. Due to the negation following them, the literal translation will be similar to 'shall we not do (A)?'. For ease of translation, this structure can be remembered as simply 'let's do (A)', or 'why don't we do (A)'.

As with all structures that use う or よう, ようではないか will be attached to the end of a verb indicating the action which is being suggested.

• 正々(せいせい)堂々(どうどう)と戦(たたか)おうではないか。

  Why don't we fight fair and square?
• この問題(もんだい)をどう解決(かいけつ)するかみんなで考(かんが)えようではないか。

  Why don't we all think about how we can solve this problem?

Alternatively, the abbreviated form of じゃない may be used in place of ではない.

• こういう時(とき)こそお互(たが)い助(たす)け合(あ)おうじゃないか。

  Why don't we help each other, especially in times like this.
• せっかく日本(にほん)に来(き)たのだから、食(た)べれるだけの日本食(にほんしょく)を食(た)べようじゃないか。

  Since we have come all the way to Japan, why don't we eat as much Japanese food as we can.

Despite this, ようではないか is primarily a formal grammar structure, so will most often use the unabbreviated version, or even more polite ようではありませんか construction.

Fun-fact

Occasionally, this grammar structure may be seen preceded by もらう. In these cases, it is usually challenging the listener to do something. This can be interpreted as 'why don't I have you do (A) then'.

• もっと綺麗(きれい)に壁紙(かべがみ)の張(は)り替(か)えができるのなら、張(は)り替(か)えてもらおうではないか。

  If you think that you're able to reapply the wallpaper better, then why don't I just get you to do it?
• 乗(の)せていってくれるって言(い)っているんだから乗(の)せて行(い)ってもらおうではないか。

  They said that they will give us a ride, so why don't we have them give us a ride.