に難くない【にかたくない】

に難くない means "it is not hard to imagine (guess, understand)": given the circumstances, anyone would reach the same picture. It follows a handful of words for thinking – そうぞう想像, すいそく推測, りかい理解, よそう予想, and the verb さっする察する in the dictionary form – and そうぞう想像にかたくない難くない is by far the most common.

What is imagined comes first as the topic with は, often a clause ending in こと or a question with か. It is about ease of the mind only, never physical ease: ×持つに難くない.

がたい難い here is read かたい: にかたくない, not にむずかしくない. It is the same かたい that turns up as がたい in しんじがたい信じがたい, "hard to believe", but に難くない is a fixed phrase of its own.

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に難くない is literary: essays, editorials, speeches. In conversation, say そうぞうがつく想像がつく or かんたん簡単にそうぞう想像できる.