An organism exhibits a mode of organisation very different from a machine. It is more than the sum of its parts. Cells and bodies are not well-defined structures but actually stabilised processes (see eg. previous post). Vitalism attributes the wrong kind of specialness to life, but nonetheless, living beings have a purposiveness that cannot be derived from mere physical-chemical processes.
Psychiatry, therefore, needs to update its biology from mechanism to organicism. Mechanical explanations are insufficient for an account of the totality of human nature. Psychiatry's primary object is not the brain but the person living in relationships. This fundamental failure to appreciate this philosophical reality is damaging psychiatry.