Hierarchical Theory of Knowledge
One more on concepts! I know you love it!
We've already hinted at a lot of things along the way. First, we talked about concepts having a genus and differentia as part of their definition. This rests on an interesting assumption. In order to have a genus, the concept you're referring to must be part of a larger category. A larger concept, actually.
So let's just jump right in. You have a bunch of concepts in your head. Part of the process of a thorough integration of those ideas is to be able to see how the concepts interact with one another. If you can tell what concept is the genus of your particular concept, you place it within a framework in your mind that's organized by the logical relationships to other concepts. You'd be able to see how it relates to the genus concept, and that it's a sub-divided concept. You'd be able to see how it relates to the sibling concepts, which are the other concepts under that genus. But this knowledge multiplies. If you know where the genus-concept fits in with other concepts, you start seeing a kind of logical mapping.
Think of it like a family tree, that goes all the way back to Adam and Eve (suspension of disbelief, please). At the top is the widest level of abstraction. It would be something like "Everything". Skipping way down, you'd see high level concepts that could in turn be subdivided into lower level concepts, and on down. At the bottom of the tree, you'd have the concepts that are directly connect to reality through perception. These would be the perceptual concepts. These are concepts formed entirely with perceptual data, and no conceptual data.
Pretty picture, aye? I'd like to quickly note that rationalists might see the same structure, except for them you start at the top of the tree instead of the bottom. They take a few axioms, and intend to deduce the rest of the world. Whereas we start with perceptual data, and abstract on upwards.
In terms of integration, the picture is also useful. Imagine you have a concept, or a mini-tree of concepts, but you don't know how to connect it to the rest of the tree. You may be missing some conceptual link. If you identify the link, it will help you to further integrate your thoughts.
Now for the sad news. The picture is flawed. It's kinda of useful at first, but it misses some critical ideas. For instance, with this picture each concept has a set of siblings, and only one set of parents (genus). In fact, it's not the case. Abstractions happen in a lot of ways, and a particular concept can be used to form very different higher level concepts. For instance, you might see a 'hamburger', and think it'll abstract to food. But it might also abstract to circular objects. Or it might abstract to 'destination for cattle'. Or how about water? It might be a requirement for human life, or what falls out of the sky, or simple chemical compositions, or materials that melt at room temperature, or any number of other things.
So the chart is a little messier. No big deal. You're still able to integrate your knowledge better by understanding the relationships between concepts.
There's something else to note as well. When you deal with perceptual data, the abstractions are usually a little hard to describe without pointing. That's because the referents are not concepts themselves. They're specific things. You have to say "My car is red" or "That leaf is green".
But although they're harder to describe, they're usually clearer. That's because you can see them directly. As your concepts become more abstract, it becomes more difficult to really grasp them. The further you get from perceptual data, and consequently from directly dealing with reality, the more likely it is that your understanding will be flawed. To reach very high levels of abstraction, you need to make sure your basic concepts are very well understood. If you abstract from a concept that you don't thoroughly understand, the result will be vague and difficult to use. If you abstract again after that, you get more muddled. At the highest level, you may not be able to use the information at all. Think about concepts like 'justice' or 'art' or 'government' or 'reason'. Each of these is a very high level of abstraction. You may have a hard time coming up with a good definition for each. You may not even know their sub-concepts.
This is what we call the hierarchical theory of knowledge. It just means that there are different levels of abstraction, and the higher level ones are built off of the lower level ones. There are a number of implications of this theory, as you can already see.