How to say "self-evident" in Japanese

• 自明じめいCommon
  na-adjective, no-adjectiveCovers the core sense of 'self-evident' — something obvious without argument or proof, as in logic or mathematics. It also extends to 'self-explanatory', making it the standard go-to word.
  ジョーダンがこの実験じっけんでメイン・エンジンを交換こうかんしたことは自明じめいである。↗

  That Jordan replaced the main engine in this experiment is self-evident.
• 自ずから明らかおのずからあきらか
  na-adjectiveAlso means 'self-evident', with a nuance of something becoming clear of itself, naturally. It is less common than 自明 and suits more discursive or written contexts.
  そのことは、各かく研究けんきゅう分担ぶんたん者しゃとこのテーマとの関係かんけいを瞥見べっけんすれば、おのずから明あきらかとなる。↗

  That fact becomes self evident if you take a look at the relation between this theme and those leading research on it.
• 知れたしれた
  pre-noun adjectivalMeans 'obvious' or 'plain, goes without saying' rather than strictly 'self-evident'. It is less common and often carries a dismissive tone, so it is seldom the word you want for the logical sense.

Use 自明 for the ordinary sense of needing no proof or explanation; the other two cover similar ground but are less common, so 自明 is usually the safe choice.

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

• 自明じめいself-evident
• 自ずから明らかおのずからあきらかself-evident
• 知れたしれたobvious