In academic fields, particularly in science, practitioners are often careful to to say they have confidence in something rather than saying they believe in it. Example: "I am confident the theory of evolution" instead of "I believe in they theory of evolution". This distinction is important, because having confidence imputes having a body of evidence that leads the speaker to find the idea probable; belief implies having faith, which requires no such evidence, and no empirical means to estimate how likely the idea is or not.

In Japanese, it seems that 確信する is the closest means of communicating "to have confidence in". But this phrasing uses 信, which means faith or belief, and has strong (?) religious connotations. Canvassing Japanese L1 speakers I've found no way to avoid using 信 and no way to avoid communicating some degree of (blind) faith.

So my question is: Is this (pedantic) degree of precision possible in Japanese? Is anyone aware of examples where this distinction is made?

Corollary: Am I mistaken in associating 確信する with 信じる?

  • I don't think the pedantic level you want even works in English. (1) Confidence already includes faith. (2) Faith / belief don't always have strong religious connotations -- at the most basic level they just mean to accept something is true (though sometimes in an evidence free way [I believe this thermometer works correctly). (3) Belief / faith don't always imply a lack of evidence or empirical support.
    – virmaior
    Sep 29, 2018 at 2:46
  • Separately the Japanese word most used for religious faith is 信仰
    – virmaior
    Sep 29, 2018 at 2:48
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    For your last comment, that's a confused way to understand the meaning of Japanese words. / For your earlier comment, my point is that confidence = con + fidense = "with + faith" by etymology. My claim is not that when we use the word "confidence" we mean religious faith but that it's shoddy to derive the meaning of a word solely from its components as you're doing in your later comment.
    – virmaior
    Sep 29, 2018 at 3:06
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    @ColinStark "fido" is a cognate to "fides" (meaning they have the same origin) and "fides" means faith. The original word thus split into two words to convey the different nuances, in exactly the same way that Japanese words containing the kanji for faith have been nuanced and gotten different meaning. Your way of thinking about languages is just completely wrong. But sure, if you want to go around saying 有力 in your daily life, please, go ahead, but people will think that you are really weird. Also I'm not really sure that word is exactly what you want to say.
    – a20
    Sep 29, 2018 at 11:29
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    Please look up the etymological fallacy.
    – user1478
    Sep 29, 2018 at 20:05

3 Answers 3


So you are worrying just because there is 信 in it? 確信 and many other compounds using 信 (信頼, 与信, 信用, ...) have no religious implications, and they are usabe in wide range of scientific contexts related to reliability, credit, trust, confidence, etc. It's not about blindly believing in something. For example "95% confidence interval" is 95%信頼区間 in Japanese. (As an aside, 信 also means signal and message.)

That said, 確信している is a strong yet subjective statement that means you have almost 100% confidence based on the (scientific) knowledge you already have. If you used it in a serious academic manuscript, it can look fairly subjective. Normally, you should say 可能性が高いと考えている or something similar at most, no matter how confident you are.

Outside manuscripts, when you think you have enough supporting facts, you can safely say something like 無人自動車運転は10年後には普及していると確信している in interviews, lectures, etc.


The following words are heavily used in non-religious contexts and so do not have necessarily a religious connotation.

But it is also possible to be more objective and instead of saying what you believe or don't believe, make statements directly about the subject. For example instead of saying:
"I believe in the theory of evolution".
you could say:
"The theory of evolution is widely recognized by scientists"

In this way you can be more dispassionate and objective by avoiding making statements about yourself and talking directly about the subject.

  • Well, I am a scientist (geophysicist), so there are occasions where I need to express an opinion, not simply say "such and such is widely recognized by scientists". This is really the main point of my question: how to make this point without implying the opinion is faith-based. All of your suggestions carry some degree of this faith implication, so my question remains. Sep 29, 2018 at 2:45
  • "The theory of evolution is widely recognized by scientists" - どうやってそれを言うんですか? Sep 29, 2018 at 2:47

If you want to get rid of the factor of faith, you can say (theory)を 有力{ゆうりょく}(だ)と 考えて/みなして いる.

  • これがめちゃ良い見たい。例えば、「進化論を有力だと思います」。ありがとう! Sep 29, 2018 at 6:58
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    @ColinStark There is a huge difference in the degree of confidence beween 確信している and 有力である. 有力 just means "predominant (as compared to other theories)". Is it really what you want?
    – naruto
    Sep 29, 2018 at 10:52

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