Functional disorders that we observe neurologically primarily pose terminology problems: some of them such as migraine, narcolepsy, restless legs syndrome have a recognized nosographic status, although without demonstrable lesions; others are interpreted only as somatic manifestations of psychic conflicts. There is also the risk that the "functional" diagnosis masks - as prejudice - lesional pathologies not adequately investigated with the available technology, leading to serious clinical errors. Moreover, even in presence of a probable psychogenic disorder, patients tend to reject the "functional" diagnosis, for cultural reasons linked to the old philosophical separation between diseases of the body and mind (the latter with a "lower" status). The current evolution of neuroscience should lead us to the conclusion that all so-called "functional" disorders are manifestations of cerebral suffering; at the same time an existential approach to the disease must make us wary of reductionist conclusions, because the clinical expression of a lesion is in the great majority of cases modulated by the culture and the history of the patient.