In response to Barefootboom I tried to figure out my take on 'knowledge':
I've been struggling with this for a while. I can't really get a handle on knowledge with regard to truth or justification. My mind tends to work in the concrete rather than the abstract, so maybe that's why.
So, what I can get a handle on, or at least I feel I can, is information (e.g. Shannon). Information is merely laid down in the brain, using the physicalist view, in patterns that vary according to person, time, current brain state, etc., acquired through the combination of genetics, development and sensory input and so on.
Sticking with the physicalist view that consciousness is a manifestation of brain activity that gives an appearance of the 'mind', then the processes of the mind consist of the manipulation and regurgitation of an individual brain's information at any particular time - outwardly, to others, an external representation of the internal information.
So what we call individual 'knowledge' is nothing more than continuously changing pattern of transformed information. Add into the mix other brains all trying to perform the same task, each with their own internal mix of this 'knowledge', then it's no wonder we struggle to find agreement on what we understand any particular piece of knowledge to be. If there is any 'truth' out there beyond human experience then we're unlikely to acquire or agree on any 'true' interpretation of it.
Why do we want to search for a truth of any kind? Why must we agree? I don't know what the biological driving forces might be, other than it could be viewed as yet another manifestation of the consequence of housing selfish genes. But it's pretty clear we are motivated to question, to understand, and to agree on 'truths'.
In this model there is no absolute truth, at least not that we can get at. There is only knowledge as information. What we make of it and how useful it is determines whether or not it is 'justified true belief', though I've never liked that phrase (because I couldn't understand it). And I think this is how such variety in understanding can be explained; how we arrive at such a debatable position about what 'truth' is, what god is, if god exists, what morality is, etc. In some respects this is a utilitarian view, but I don't see anything wrong with that.
If this interpretation is the case then it also explains in some way the success of science and its methods and why we find them useful: the use of repeatability to establish knowledge as a consistent set of information over time, space and environment; the use of logic to establish what we can conclude or at least what we can use as a working model. Science even goes to great lengths to iron out the noise and the vagaries of human fallibility by using double blind tests and performing statistical analysis on the data to make sure, as much as we can, that the results actually represent useful knowledge/information. In other words science helps us to get as good an agreement on any 'truth' as we can reasonably expect.
Beyond this view of knowledge I struggle with much of the philosophical contemplation of it. It seems to me that it's quite easy to analyse yourself until you vanish up your own ass, and I feel that that's what some philosophers do when considering truth and knowledge. Maybe it's just my ignorance of some of the finer points.