I think you have to deal with the confused situation that we're faced with by siezing on the glimpses and particles of life, seizing on them and holding them and trying to make a pattern of them.
-- poet Archibald MacLeish
Fundamentally, all perception is direct: the sight of a rose, the smell of a rose, the thought of a rose. However, we do not simply sit passively in life, silently witnessing a flow of chaotic images. Instead, we pay attention, and notice that patterns apparently connect these perceptions.
These apparent patterns are what we call knowledge beyond direct experience. Knowledge is simply thus: in the stream of perception are patterns. These patterns connect actual sights and sounds with memories of sights and sounds, and expectations of sights and sounds, into a cohesive perception called an "idea."
Perception is the direct experience of a certain quality of awareness: particular sights, sounds, smells, tastes, feelings, and thoughts. Idea, concept, knowledge, belief -- these refer to thoughts that attempt to explain or connect other perceptions.
An idea groups together certain sights, sounds, and so forth, into one abstract bundle. My idea of chair involves memories which I label the sights and sounds of past chairs, as well as a set of expectations which I believe predict how chairs will look and behave in the future. My idea of a chair is basically a theory of how certain perceptions will behave.
It is rather pointless to ask, "When I see a chair, is the chair really there?" A more fruitful question is: "When I say that I see a chair, what do I really mean?" One way to answer is: I mean that in my awareness is something I call sight of a chair, and something I call the idea of a chair which is a pattern connecting memories and expectations about what will happen if I move the chair, sit on the chair, pick up the chair, and so on. If there is a chair "really there," apart from the pattern in my mind, I have no knowledge of it; my only direct knowledge is of the sight and of the idea.
The above attempt to define knowledge is loose and not final. Knowledge itself is loose and not final. Like a cloud, knowledge does not have well-defined borders.
To look at one aspect of the fuzziness of knowledge, let me ask, do you know what 2 + 2 is? You probably would say yes. Now let me ask, did you know what 2 + 2 is the moment before I asked you? If you say yes, then it should be clear that knowledge is not limited to conscious awareness. If knowledge is not limited to immediate consciousness, what are its limits? Can the conscious mind probe for limits which exist beyond it if at all?
To look at another aspect, whatever idea we come up with about what knowledge is, is itself a piece of knowledge. As such, it is subject to the limitations of conscious knowledge. If we cannot get an "outside view" of knowledge, we might never understand it in its entirety.
To look at yet another aspect, all our ideas are approximations, not exact descriptions of what is really there. My everyday idea of "chair" says that chairs are solid objects, yet science teaches that chairs are made of energetically swirling invisible particles. My idea of "solid object" is just an approximation of how the chair will react. (Science's idea of a chair is also approximate, but more precisely defined than our usual one.)
We now reach a puzzling point. We are attempting to look into the nature of knowing, but the act of looking with the intellect is subject to limitations that may prevent us from getting a good view. Can we make the subject clearer?
For Further Exploration
The philosophically minded and curious can browse these sources elsewhere on the Web:
- "Meaning and the Problem of Universals, A Kant-Friesian Approach:" a good overview of theories about ideas as abstractions