In this article, we detail the contributions of the Psychopathy Checklist (PCL) and the PCL-Revised (PCL/-R; Hare, 2003) for the scientific study of psychopathy and highlight its role in bringing order and clarity to the field. We explore how the introduction of the PCL/-R facilitated the construct validation of and explorations of mechanistic underpinnings of the Cleckley psychopath, focusing specifically on the response modulation hypothesis (RMH; Patterson & Newman, 1993). We argue that the PCL/-R has been critical for advancing research on the psychopath initially outlined by Cleckley (1941) in The Mask of Sanity. In discussing current debates surrounding use of this measure, we advocate for the continued use of the PCL/-R as well as the development and use of alternative assessment measures, proposing a method for integrating and advancing different conceptual and measurement approaches. Overall, we call for careful consideration, delineation, and comparison of hypothetical constructs being studied in modern psychopathy research through the provision of evidence for the construct validity of the construct(s) being studied.
