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?
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 ...
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.
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.
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.