In my view, knowledge is a subjective feel, but there's a nice story behind it.
The subjective feel appears circular: I say that I know when I can't not know.
The story lies in the cause of this subjective feel: to know is to recognize.
is involuntary, hence the modality of 'can't not know'. It is also
non-grounded. The subjective feel is the knowledge.
recognizing a person. Your mother walks through the train station and
you pick her out of the crowd. This recognition is not based on any
particular rule or principle, not based on any essential features, not
based on any inferential process.
Yes, you could be mistaken in
the train station - an alien disguised as your mother may have appeared
instead. But your knowledge is not at fault. You know what your mother
looks like; that's where your certainty lies.
Recognition is a property of neural networks, and
this is what explains why you recognize, why it's involuntary, and why
it's not based on any rule or principle.
experiences seeing your mother have over time resulted in the growth of
an associated pattern of connectivity in your neural network (ie., in
your brain, ie., in you).
When a person with the appearance of
your mother is presented to you this pattern is activated. It is
automatic and involuntary. This pattern in turn activates associated
patterns. Hence: mother!
The pattern is subsymbolic; the brain
is not a physical symbol system. Hence, no rules or principles, nor
either models or representations.
The neural network part of the
story, note, is an *explanation* of how we know, and not the
justification for it or evidence for that knowledge.