The myth of the need for diversity among subjects in theory-testing research: Comments on "Racial inequality in psychological research" by Roberts et al. (2020)

This is a comment on Roberts et al. (2020), who complained about the lack of diversity in subject populations. While representativenes is essental in survey reearch or applied research that examines whether a particular intervention will work for a particular population, it is not required in theory testing research, where we establish laws of causality. Because theories typically apply to all of humanity, all members of humanity are suitable for assessing the valdiity of theoretical hypotheses. Admittedly, the assuption that a theory applies to all of humanity is also a hypothesis that can be tested. However, to test it we need specific hypothesis about specific moderating variables.