Can I know something but not be able to justify it to anyone else? I don't necessarily mean metaphysical puzzles, but everyday examples. If I cannot - and I know I cannot - prove to anyone else, all reasonable epistemic agents, that the bus is late and not early, then do I know it or just - let's suppose - believe it, perhaps due to faith in the bus network? How does KK link up with the answer: if I don't know I can justify it to anyone else, might I still know it?


5 Answers 5


Yes. And this is true of most of what we know.

Almost everything we know, we learn thru first person empiricism. It may be possible to translate and detail at least some first person empirical knowledge in sufficient specificity and detail to convince others, but this is a massive additional step that we generally do not do. Also this third person translation and justification is almost certainly not achievable for at least a significant fraction of what we know thru first person.

For anyone who doubts this, I use waking up as an example. What we "know" at that point is almost all from pure first person thinking:

  • I am me
  • I am prone
  • I am under covers
  • The sense of pressure in my interior is a full bladder
  • This location correlates with where I recall being in the past
  • Movement is possible for me
  • Moving off the prone surface will get me somewhere different
  • There is a surface I can move to that will support me
  • Etc in extensive detail

How much of this is demonstrable to a skeptical other, with enough work? MAYBE some ...

  • You're taking a very narrow definition of "justify" by requiring demonstration and the ability to convince another rational person. In that sense, very, very few things (if anything at all) can verbally be justified to others, because, at the end of the day, anything you say will just be claims, which they'd need to confirm with other evidence for them to be justified in believing it. One could also take "justify" to merely mean in the sense of explaining why you believe something (which seems more reasonable).
    – NotThatGuy
    Commented Nov 15, 2023 at 4:03
  • @NotThatGuy -- I often use this example when dealing with people who falsely claim to only believe things which are scientifically validated, by citing the dozens of things they have to believe that are not so validated just to get up in the morning. If one wants to think in terms of explaining why one believes something -- that still requires that one be able to articulate the reasons for one's belief, and generally when getting up, I have not actually done this articulating of the beleifs I act on, to myself, much less anyone else. Do you?
    – Dcleve
    Commented Nov 15, 2023 at 4:38
  • I never mentioned scientific validation, so I'm not sure what that has to do with what I said (science is merely one possible justification). I also never said I have articulated the justification for all my beliefs, but I try to find and discard unjustified one, and I would say I'm not aware of any beliefs I hold that cannot be justified in some way. Note that the question asks about "being able to" justify, not about already having a justification. Much of what you mention is quite easy to justify - you feel your covers, biology and induction says sense of pressure means full bladder, etc.
    – NotThatGuy
    Commented Nov 15, 2023 at 4:59
  • @NotThatGuy -- Per the Munchausen Trilemma, none of our beliefs are justifiable without the adoption of a logical fallacy, or abandonment of logical truth for pragmatic truth. philosophy.stackexchange.com/questions/64638/… Justification, as it is used formally, is not achievable. I adopt pragmatic truth, which can accept the validity of knowledge that does not involve overt propositional reasoning. We know that system 1 provides us knowledge, and does not do such reasoning.
    – Dcleve
    Commented Nov 15, 2023 at 16:51
  • I already mentioned that you're adopting a very narrow definition of "justify", and I adopt a broader one. Although your definition is far more narrow than what I first thought, given that you say "none of our beliefs are justifiable". In any case, your answer is rather subtle about all of this - it's not at all clear from your answer that the only justification you consider valid is a strict logical proof. Never mind that you admit you don't even use such justifications yourself, and that you deem this unachievable. It all seems a lot like playing semantic games for the sake of "winning".
    – NotThatGuy
    Commented Nov 15, 2023 at 18:14

The skeptic view (in the sense of questioning beliefs, not radical philosophical skepticism) is, roughly speaking, that if you cannot justify something, you shouldn't believe it.

The above means being able to justify it to yourself. Although if you can explain to yourself why you believe something (i.e. justify it to yourself), it stands to reason that you should be able to explain to others why you believe it.

This does not, however, mean that offering your justification to another rational person would necessarily be sufficient for them to believe what you believe. If you see someone do something, and you tell another person about it, for you that's direct sensory evidence, which is generally considered to be quite strong evidence (although people tend to underestimate how unreliable it can be, but I digress). But for them, it's merely someone else making a claim, which is fairly weak as far as evidence goes.

You may notice that I didn't actually mention knowledge above. This is because that's largely a semantic issue.

A skeptic might say that you don't "know" something if you cannot justify it (i.e. knowledge as justified true beliefs... even if the "true" part of that is questionable for me).

Others might use a different definition of knowledge that does not require justification.

And of course, others might not hold the skeptic view of rejecting unjustifiable beliefs.

  • Would you consider beliefs of this kind subjectively justified?
    – Mark
    Commented Nov 15, 2023 at 16:22
  • @Mark There is an attempt to provide a justification there, but that doesn't mean it's a good or rational justification that's sufficient to warrant belief. I don't consider any belief in a deity to be rationally justified, presuming a relatively accurate perception of reality.
    – NotThatGuy
    Commented Nov 16, 2023 at 6:34
  • I would be interested in your answer to this question. An answer to this one would be interesting as well.
    – Mark
    Commented Nov 16, 2023 at 6:50
  • @Mark The answers of Annika and JD on those questions are pretty good, and I don't really have much to add beyond that (except for the comment I left on the latter).
    – NotThatGuy
    Commented Nov 16, 2023 at 13:03
  • But Annika's open to be convinced through private revelation, but you aren't, or are you?
    – Mark
    Commented Nov 16, 2023 at 16:12

The examples @Dcleve gives in his answers for knowing "from pure first person thinking" seem to me examples for the experience of inner certainty. In most cases there is no problem to convince other persons about the facts.

The problem is to convince oneself: That one does not only have an inner certainty about the issue, but that one actually is right.

Because sometimes persons mix up inner certainty about the meaning of an event with the verification that their interpretation is right. They mix up inner certainty with knowing. And often then they do not succeed in convincing others about the extraordinary meaning of the event, which happened to them.

  • hmm interesting thanks. i think you make it sound quite mystical, which is viable in a way
    – user67675
    Commented Nov 14, 2023 at 20:08
  • 1
    @prof_ghost Please note my corrections: I refer to the examples from Dcleve.
    – Jo Wehler
    Commented Nov 14, 2023 at 21:04
  • Jo Wehler -- the more important a question is, the more I advocate for applying the methods we have developed to do cross-check in the 3rd person, to our first person empiricism. For example, whether there is a sold floor beside my bed in the morning, can be pretty critical to my health. If I am in a new location, I will check that carefully, to satisfy myself. First person empiricism can apply confirmation checks.
    – Dcleve
    Commented Nov 15, 2023 at 0:21

Most everyday examples should be justifiable to most people. The scenario where you can't prove the bus is likely to be provable to most people. The condition of "anyone" makes it more problematic.

However, cognitive science is showing that there are more types of knowing than simply propositional knowing. So there are likely some everyday scenarios you can't justify to anyone. But largely only on the basis that your experience is unique to your simulation of the experience, given your neural wiring etc.

John Vervaeke describes 4 types of knowing, one example which can capture the everyday is..."Perspectival knowing, which refers to knowing via embodied perception. It consists of seeing the world and one’s place in it via a specific point of view, and understanding (or not) the key aspects of a situation".



Yes , you can know something and not be able to justify. It’s called faith. Faith doesn’t need justification always. For example - so many people believe in God but they can not always be able to justify… it’s not that there is no justification but it’s just that you are unable to justify your knowledge which is based on faith. Another example would be - suffering. So many people believe that the suffering is bound to come and we should do something about it like developing detachment but when it comes to justification , we fail miserably. Some people just believe the opposite that there is joy and bliss.

The main motivation for holding a belief is the instinct for survival. Those with the fittest belief survive.

  • 1
    Faith is just an alternate form of justification, though. Justification in the sense used when generally talking about knowledge (that is, the definition that knowledge is true, justified belief) doesn't mean scientific or empirical justification specifically, just that there is some motivation for having a given belief. Whether the motivation is personal faith, scientific validation, the opinion of a trusted friend, simple direct observation, or any number of other options, justification in the sense being discussed is just some kind of motivation for holding a belief.
    – Idran
    Commented Nov 15, 2023 at 15:17
  • @JustinHilyard Great question…The main motivation for holding a belief is the instinct for survival. Those with fittest belief survive. I will add this to my answer. Commented Nov 15, 2023 at 16:52
  • If you mean faith in the sense of believing something in the absence of evidence or some other compelling justification, then one might ask what you mean by "know". Because that just sounds like something you "believe" rather than something you "know". Knowledge goes beyond merely believing something and implies some justification and/or correspondence with truth (e.g. "justified true belief").
    – NotThatGuy
    Commented Nov 16, 2023 at 12:13
  • "Those with the fittest belief survive" - this may apply to the sum of many beliefs, or to the tendencies that drive beliefs, rather than for individual beliefs. If you have a tendency that leads to beliefs A and B, and A is really good, but B is kinda bad, that tendency still provides a net benefit and would provide a survival benefit, even though it includes an unfit belief (as an example, if you believe what you see, you believe what you see while awake: really good, but you also believe what you see while dreaming: kinda bad).
    – NotThatGuy
    Commented Nov 16, 2023 at 12:33
  • @NotThatGuy I agree. Commented Nov 16, 2023 at 15:22

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