In light of the ongoing validity crisis in psychiatric classification, phenomenologically oriented psychiatric study has gained traction. This paper assesses two modes of investigation proposed by phenomenologists in studying mental disorders: the ideal type approach and the essential type approach. Despite the recent suggestion that they are antithetical approaches, I argue that they should constantly constrain and inform each other. In short, I advance a mutual complementarity thesis. Having established this thesis, I conclude by demonstrating how this proposal can function (...) as an heuristic strategy for effectively facilitating the recently proposed psychiatric research initiative, i.e. the ontological project of phenomenological psychopathology. (shrink)