This article, by the Integrative Psychotherapy Association, nicely explains the meaning of the term and how it differs from ‘eclectic’.
If you want green walls, you generally buy green paint. If you buy blue and yellow paints, even if you are very careful, you are unlikely to have the same degree of quality control over the emerging colour.
An integrative practitioner, is concerned with the integration of a client’s new understanding into their psyche. That is the definition and this is green paint. It is open to examination, to research, to validation, and to refutation with a view to drawing generalisms. These generalisms allow knowledge to be replicated and so applied in an evidence-based manner.
Adopting a bit of CBT (blue paint) and a bit of psychodynamic counselling (yellow paint) is eclecticism, and the outcome (50 shades of Green) is so variable that while it can be examined, researched, validated or refuted, it cannot be replicated and so can’t be generalised.
The same is true of pseudosciences that create the appearance that they are one consistent, coordinated, approach, when they are really a smorgasbord of different bits and pieces of theory that haven’t individually been validated let alone the whole.
To put this another way, Sigmund Freud had his theories, Carl Jung had his theories. While they built on each others’ they were distinct. Given the power of the intellects involved, don’t you think it is a tad arrogant to imply that because you have studied both for a few weeks that you have somehow developed a consolidated approach that overcomes the conflicts in approach that they spent years trying to address?