OBJECTIVE: The purpose of this paper is to review the theoretical basis of addressing the concept of the unique individual, one of the tasks prescribed in the Royal Australian and New Zealand College of Psychiatrists (RANZCP) Formulation guidelines for candidates, and to propose a rational basis for remediation of the problems that many candidates and other professionals have with formulation. CONCLUSION: The difficulty that RANZCP candidates and other mental health professionals have in producing a completely integrated account of an individual is multi-determined, but is partly explainable on theoretical grounds. Understanding why this task (and other tasks of formulation) is problematic requires knowledge of its intellectual history, its rationale, the tools of reasoning that it requires and the nature of the challenges that it can pose to individuals. The paper argues that a rational plan for remediation of a professional s problems with formulation requires first a formulation of those problems, drawing on the theories discussed and acknowledging the uniqueness of that individual. In answering the question, Why is this person having difficulty formulating this patient at this time? , one needs to address cultural, social and systemic factors, and psychological factors such as the degree of psychological mindedness of the person seeking remediation. Hypotheses based on the formulation about the professional s difficulty should be developed and tested by interventions.