The two types of advances—that is, increased differentiation of lower order phenomena and integration of those phenomena into larger, explanatory theories—are closely linked. In particular, the validity of integrative theories depends on the validity of the elements contributing to those theories, just as identification of important, lower order elements is contributed to by sound integrative theories. One set of implications of this perspective for clinical psychological science includes the following: When it occurs that a previously recognized psychological construct is subdivided into more elemental components that have different etiologies, or different external correlates, or that require different interventions, it no longer makes sense to treat the original entity as a coherent, homogeneous construct and to represent it by a single score. If one were to refer to such an entity with a single score, one would risk errors at both the lower order level and the higher order level. At the lower order level, one would risk compromising accurate description and effective intervention. At the higher order level, one would risk compromising valid aggregation into larger theories. To clarify the
