A main socio-structural distinction, so commonplace that we often do not take it into account in our analysis of a dataset, is the ultimately ambiguous distinction between professional and nonprofessional, or amateur. In Chapter 6 on citizen science, for example, we shall fail to mention George Kelly’s theory of personal science, which can be interpreted to mean that every human being is a psychologist, developing throughout life a distinctive theory of the human mind, supported by empirical observations of events and experimental behavior.