A core idea is any idea selected as the exploratory center of a mind lens, especially ideas directly related to values, virtues, and principles. An idea is core because a mind chooses to explore it, not because it is inherently more important than other ideas.
Core idea is a common term with a specific use within TST. You configure a mind lens that focuses on a core idea using four roles: value, virtue, principle, and action. As in the good, a character trait, the guidance, and behavior. And any idea can be crammed into an idea axiom, but ethical or action-oriented ideas work best.
For example, take the core idea of knowledge, which is related to the virtue of wisdom. With the core idea and virtue set, we just need to choose what value, principle, and action we want to explore. If we set the value to living well, then perhaps we might set the principle approach learning with curiosity and the action to read lots of nonfiction books. You might then say,
“I value living well, so I cultivate wisdom, stay curious, and read nonfiction books to deepen my knowledge.”
And, of course, you could configure those roles differently. That’s the beauty of exploring ideas through different mind lenses. One mind might connect knowledge to wisdom, curiosity, and reading. Another might connect knowledge to skepticism, investigation, and experimentation. Both can construct useful mind lenses.