The Scientific Status of Individual Differences

Abstract

The relationship between the two disciplines of scientific psychology is a very important current issue. Unfortunately, the issue has been current far too long and has produced opinions that are far too extreme. On one hand, these opinions are represented by the prevalent but radical view that studies without manipulated variables do not qualify as scientific. This view not only disqualifies most individual differences studies as scientific but also disqualifies most of the work in other scientific fields. Judged by the criterion of including manipulated independent variables, the entire fields of astronomy, geology, and anthropology must be considered unscientific along with most work in physics and biology, which like individual differences tend to focus on measurement and observation and establishing empirical and then theoretical relationships among measured variables before manipulating them. Surely something is wrong with the practice—only found in psychology—of considering manipulated variables as the hallmark of science when so many fields that are unquestionably scientific manipulate so few variables.