As a field, transpersonal psychology is largely ignored, and at best marginal from the perspective of mainstream science, which is dominated by scientistic materialism. Its prime subject matter, transpersonal experience, is held to be inherently illusory and frequently pathological. From a scientistic perspective, mind is considered to be only the operation of the brain and nervous system. Experiences which appear to transcend these physical limits are illusions. The author argues that essential science (the basic scientific method), as it has been applied in the similarly criticized field of parapsychology, demonstrates with high scientific rigor that the mind is more than the brain and so provides an empirical basis for considering many transpersonal phenomena as having reality. While there are political costs in allying with another controversial field, in the long run the case for transpersonal psychology can be based on a rigorous scientific base such as parapsychology provides.
Tart, C. T. (2004). On the Scientific Foundations of Transpersonal Psychology: Contributions from Parapsychology. Journal of Transpersonal Psychology, 36(1), 66–90.