Among people who try to be careful about ideas, it's common to draw distinctions like the world vs. one's model of the world, or an idea vs. the words used to express that idea. There is (at least for me) a tendency to feel as though these are binary distinctions, to imagine a two-level model.

It might be better to think in terms of a three-level model instead, to draw a three-way distinction between:

  1. a fact that exists in the world,
  2. a concept that understands or models a fact, and
  3. a text that expresses that concept.

This allows much clearer discussion of how ideas work.

When we notice things about how the world works, we're translating Facts into Concepts by observation. When we explain our ideas, we're translating Concepts into Expressions by composition.1 When we hear or read someone else's words and understand what they're saying, we're translating Expressions into Concepts by reading. When we apply our knowledge to practical ends, we're translating Concepts into Facts by engineering.

     Observation       Composition
     ---------->       ---------->
 Fact           Concept           Expression
     <----------       <----------
     Engineering         Reading

1. in the sense of composing a text or a symphony, not function composition