How to say "fundamentally" in Japanese

• 基本的にきほんてきに
  adverbCovers 'fundamentally' in its 'basically, at bottom' sense: summing up the essentials of a situation or giving your overall take on it. A less common but direct rendering of the word.
  人間にんげんは基本的きほんてきには善良ぜんりょうだと私は信しんじている。↗

  I believe people are basically good.
• 原則としてげんそくとして
  expressionIts core meanings are 'as a rule', 'in general' and 'in principle': it frames a statement as a general rule, typical when stating a policy. For 'fundamentally' it is only a marginal match.
  年金ねんきんの額がくは原則げんそくとして前年ぜんねんの物価ぶっか変動へんどうにスライドして算出さんしゅつされる。↗

  As a general rule, the pension amount is based on price changes in the previous year.

For 'fundamentally' meaning 'basically, at bottom', 「基本的に」 is the fit; 「原則として」 really renders 'as a rule' or 'in principle' and only marginally covers 'fundamentally'; both are less common choices.

Usage comparisons are AI-assisted and cross-checked by multiple models; for study reference only

• 基本的にきほんてきにbasically
• 原則としてげんそくとしてas a rule