To reduce or to integrate: psychiatry's dilemma.

Three conceptual approaches to psychiatry may be distinguished: the somatic (biological); the psychological (psychodynamic, psychosocial); and the integrative (holistic, biopsychosocial). The first two emerged in the early nineteenth century, the third - in this century. All three continue to vie for influence today. The author traces their historical precursors and discusses their current state. He argues that psychiatrists need to apply methodological reductionism but adopt an integrative orientation in theory and clinical practice.