• causal systems;
  • natural kind;
  • network analysis;
  • posttraumatic stress disorder;
  • psychiatric diagnosis;
  • social construction

The ontological status of posttraumatic stress disorder (PTSD) has long been a focus of intense controversy. Is PTSD a natural kind discovered recently by astute clinicians, but present throughout history and across diverse cultures? Or is it a socially constructed artifact arising in the wake of the Vietnam War? In addition to covering issues relevant to this debate, I describe another interpretation of PTSD orthogonal to the natural versus artifactual dichotomy. Inspired by the causal systems approach to mental disorders pioneered by Borsboom and his colleagues, I suggest a causal system interpretation of PTSD is a scientifically more profitable approach than either the social constructionist or natural kind interpretations of this disorder.