Critical trends in psychiatry are abundant today. Their impact on how psychiatry is currently practised is considerable. Yet what deserves close examination is the extent to which these modes of critique (anti-psychiatry, liberation movements, activism, existential, narrative or hermeneutic approaches, theories of values, psychoanalysis) inherently belong to or have become part of the very system that they criticise. Despite their political, social or scientific influence, which is undeniable, their critical power is often limited by their inability to radically challenge the deeper anthropological and philosophical presuppositions on which mainstream psychiatry rests. It can be argued that Foucault offers such a challenge. Implementing his historico-philosophical method, Foucault is sceptical of the anti-psychiatric quest for non-oppressive modes of psychiatric power and the humanist and postmodern efforts to moralise or relativise psychiatric truth. All these modes of critique rest on preconceived notions of nature, power and truth and have been integrated by the pluralism of the psychiatric universe. Yet Foucault's critique seeks precisely the opposite: to explore a new anthropological conception of insanity that has the power to challenge the legal, moral or reductionist constraints under which medical truth currently operates.