Understanding concrete ideas is easier than understanding abstract ideas

Abstracting an idea is one of the core manipulations of an idea, involving stripping away unnecessary context, leaving a broader idea in its place. This can make them harder to understand, as they effectively stand for many different concrete ideas.

It can be common to under and overfit abstract ideas, for example. That is, apply them to too-specific situations, or over-apply them.

Abstract ideas are lenses are mental models - they're the same thing. A way of generalising a pattern we have recognised. This means it is still important to be aware of the lens you are using.