Functional reasoning in psychiatry
Résumé
Two types of functional reasoning are commonly used in psychiatry. For
the first type, a mental disorder is conceptualized as the impairment of a mental
function: this type of reasoning is nowadays oriented towards research on neurobiological
disorders that are supposed to underlie mental disorders. For the second type
of functional reasoning, a function is assigned to a mental disorder—that is, a disorder
is considered as a defensive process in a mental or family system—and this
function has an etiological role, not only in maintaining the disorder, but also in
triggering it. We detail this second type of reasoning that gives a strong explanatory
value to the notion of function. We briefly analyse some variations of this explanatory
value in the psychoanalytic, cognitive-behavioural and family/systemic models
that are among the main conceptual frameworks currently used in psychiatry.
Finally, we attempt to clarify certain epistemological consequences of the irreducibility
of functional etiological reasoning in psychiatry.