I just had a little thought about how to explain the Ontologies that you find on the Semantic Web. You could say:
An Ontology is a bit like a thesaurus, but with a hierarchy of terms each with its own properties
SemWeb people: Does this make sense?
Non SemWeb people: I wonder if this is a useful way to understand Ontologies.
2 responses so far ↓
Yes…but this definition seems a bit passive. You neglected to mention that the power of a knowledge representation is in the relationships it supports and from the theories that they embody. Taxonomies, thesauri, etc. only deal with a very few types of relationships, e.g. abstraction.
Indeed Ontologies are a lot more complex than taxonomies, and this phrase was merely to help people who are not necessarily in the Semantic Web or even the Computer Science world.
Ontologies are extremely useful things based on years of research into a type of logic called Description Logic. With an Ontology language you can build highly structured types which can be reasoned upon.
As you say, Mills, taxonomies are quite flat structured and can only really deal with how terms relate to other terms. Like you say, abstraction.