べくもないUtterly impossible
べくもない is an elevated way to say that an action, possibility, or judgment is wholly impossible or beyond reasonable expectation. It is especially common in fixed expressions meaning “beyond doubt,” “impossible to know,” or “impossible to imagine.”
What the expression actually says
This construction does more than report a practical inability. It presents something as outside any reasonable possibility: unknowable, unimaginable, beyond hope, or beyond dispute. The surrounding verb determines the most natural English wording.
A conventional use
この結論が妥当であることは、疑うべくもない。
There can be no doubt that this conclusion is valid.
Analyze疑うべくもない conventionally means “beyond doubt” or “there is no room to doubt.” It does not describe someone trying and failing to perform the act of doubting.
Natural formal combinations
The pattern is most convincing with verbs that naturally support a sweeping formal judgment, particularly knowing, imagining, doubting, comparing, and hoping.
Choosing among impossibility expressions
べくもない makes an elevated, categorical assertion of utter impossibility. ようがない neutrally says that there is no way or method to do something, while はずがない rejects something as contrary to what the speaker reasonably expects. Also keep this construction separate from formal べく used by itself to express purpose or an intended course of action.
More examples
その作品が後世に与えた影響は、疑うべくもない。
The work's influence on later generations is beyond doubt.
Analyze誰が最初にこの歌を作ったのかは、今となっては知るべくもない。
It is now impossible to know who first composed this song.
Analyzeその時、彼女が感じた孤独は、私には想像すべくもない。
I cannot begin to imagine the loneliness she felt then.
Analyze両者の技量には大きな隔たりがあり、比べるべくもない。
Their levels of skill are so far apart that they are beyond comparison.
Analyzeこの状況で全面的な勝利など望むべくもない。
Under these circumstances, total victory is beyond hope.
Analyze幼い私には、父の沈黙の意味など理解すべくもなかった。
As a child, I could not possibly have understood what my father's silence meant.
Analyze