On ego development and the structure of personality

present a theory of ego development as composed of several substructures related so that achievement of a given stage in one substructure is necessary but not sufficient for achieving the corresponding stage of another. The postulation of an exact relation belies what is known of the texture of human behavior and is premature in the absence of precise measurement of the several substructures and precise matching of stages. An alternative, the empirical method of simultaneously constructing a measure of ego development and portraits of the several stages, which Snarey et al. criticize for lack of strict logical coherence, is in the best tradition of contemporary science. The stage portraits are “prototypes” or “fuzzy sets.” Any mental structure can be divided into substructures, but the most general, superordinate structure is likely to prove most useful.