Randolph Nesse argues that evolutionary theory is the key element in elaborating a valid criterion demarcating the normal from the pathological in psychiatry. By focusing on the application of Nesse’s criterion on the demarcation of normal low mood from pathological depression, I argue – contrary to Nesse’s claims – that evolutionary theory cannot generate a valid criterion from the differentiation of normal low mood states from pathological depression. Indeed, expression in conformity to evolved functions cannot constitute a sufficient condition for (...) normality, as Nesse’s project should imply. Moreover, grounding normality in evolved functions presupposes a kind of fixity of our emotional states, which seems unwarranted in the light of a constantly changing environment. As a result of these limitations, I suggest that the relevant distinction in psychiatry should not be “normality” versus “abnormality”, but, rather, “that which requires intervention” versus “that which does not”. (shrink)