A schema is the mind’s idea of a repeatable pattern.
In chapter 5 of 30 Philosophers, it is defined like this.
A schema is a mental structure we employ to organize and interpret information. We classify things into schemas, which we can then modify by adding or removing elements.
Schemas help you recognize patterns which helps you manage what something is, what it means, and how you should respond. You do not start from scratch every time you see a dog, enter a restaurant, or hear a political slogan. Your mind brings templates.
A schema can be simple, like your idea of a normal breakfast or a normal dog. It can also be complex, like honor, duty, or respect. Larger schemas are built from cultural expectations, emotional memory, and inherited language.
In TST, schemas are used traditionally and live inside and across frameworks. While a framework is a bounded system of ideas, a schema is a reusable template within that system. Some schemas appear in many frameworks at once. For example, a schema of respect might appear in your family framework, your work framework, and your religious framework.
Schemas also help shape your two major lenses. Your worldview is your lens of the world, and it is built from schemas about reality, people, nature, and meaning. Your identity is your lens looking at the self, and it is built from schemas about who you are, where you belong, and what kind of person you are trying to become. Schemas are useful because they let you think fast, but they can also distort perception. If a bad schema becomes normal, you may defend it before you question it. That is why TST treats schemas as powerful, practical, and dangerous. They help us live, but they must be examined.