The scientific concept of intelligence has been heavily influenced by the technology of measurement. The variables which can be measured have been made the operational definition of intelligence. This approach differs from a deductive approach, in which a theory of cognition in general is used to derive the sorts of measurements that must be taken to describe an individual's cognitive competence. The cognitive science approach to cognition in general can be used as a base theory. This theory generates requirements for individual intelligence measurements which differ from tests used to predict performance in some (perhaps ill-defined) criterion situation. The use of theory-defined measures of individual mental competence is different from the use of measures that are justified in terms of their predictive validity. (Author/GDC)