2.1 WHY CLASSIFY THINGS AT ALL?

Human beings facilitate learning and memory by classifying what they experience and what they need to know. It is deeply embedded in the cognitive process. Somehow, toddlers who see their first dog and hear from their mother or father that "it's a doggie!" immediately store that name with the vision and, thereafter, seem to recognize other dogs, despite differences that can be significant. Unfortunately, the initial learning isn't perfect. The toddler tends to call every furry four-legged animal with ears and a tail a "doggie." They have clearly classified the first dog they saw by certain obvious features, attributes, or characteristics. The "doggie" has four legs, so all four-legged animals might be identified as "doggies." But, the "doggie" is also furry, so, eventually, only furry four-legged animals are identified as "doggies." And so the process of classification for learning and memory goes. It evolves to allow greater and greater differentiation based on more and more subtle similarities and/or differences.

Materials, processes, and methods are also classified to facilitate learning and recall. But, beyond learning and recall, we classify things based on and in order to see familial relationships. We look for and use obvious similarities and obvious differences to classify. From these, we evolve a hierarchy or, more properly, a taxonomy; from the Greek taxis, meaning "arrangement." Something seemingly derived directly from another in a taxonomy has a "daughter mother" relationship. Something derived from the combination of two things at the next-higher level in...