Abstract

This chapter relates the problem of demarcating the pathological from the non-pathological in psychiatry to the general problem of defining ‘disease’ in the philosophy of medicine. Section 2 revisits three prominent debates in medical nosology: naturalism versus normativism, the three dimensions of illness, sickness, and disease, and the demarcation problem. Sections 3–5 reformulate the demarcation problem in terms of semantic vagueness. ‘Disease’ exhibits vagueness of degree by drawing no sharp line in a continuum and is combinatorially vague because there are several criteria for the term’s use that might fall apart. Combinatorial vagueness explains why the other two debates appear hopeless: Should we construe ‘disease’ in a naturalistic or in a normative way? Neither answer is satisfactory. How should we balance the three dimensions of pathology? We do not have to, because illness, sickness and disease (narrowly conceived) are non-competing criteria for the application of the cluster term ‘disease’.