How do I practice backwards compatibility?

The most direct way to practice backwards compatibility is through a focused exercise: Identify one belief you've recently updated. Write down three situations where your old belief gave you a correct prediction. Now test: does your new belief also give correct predictions for those same situations? If not, your new schema isn't backwards compatible — it's just different, not better. Revise it until it covers both the old successes and the new cases that forced the change.

Common pitfall: Adopting a new mental model that explains the anomaly that triggered the change but quietly drops coverage of situations the old model handled well. You feel enlightened because you solved the puzzle that was bothering you, but you've introduced silent regressions — areas of life where your thinking is now less reliable than before.

This practice connects to Phase 16 (Schema Evolution) — building it as a repeatable habit compounds over time.