For example, we can not test the Id, Ego, or Superego as defined by Freud, but these are foundational ideas in psychology and they are used in

For example, we can not test the Id, Ego, or Superego as defined by Freud, but these are foundational ideas in psychology and they are used in therapy to understand unconscious and conscious motives and drives. How do we justify what we do if we can not do research on it?