In everyday life, non-linear causal relationships can be investigated excellently and that is precisely why applied science appeals to me. Practice is leading in applied science. In the context of psychopathology, this means that we do not only look at general knowledge that can be derived from a large number of people with a certain mental condition (disorder). The emphasis is mainly on people who, despite a certain diagnosis, do not (or no longer) experience the problems that most people with such a diagnosis encounter.