Psychology is as difficult as any other science. Its subject matter is of the greatest complexity. There are enormous practical and ethical constraints on research. Even an apparent advantage is a double-edged sword. People may have better intuitions about other people than about subatomic particles, cells, or stars, but by being both investigator and subject matter, those people who also are psychologists are prone to personal biases and subject to social pressures that are uncommon in other disciplines.

The study of personality is as difficult as any branch of psychology. Unlike colleagues in other parts of the field, the personality psychologist cannot be content with studying isolated aspects of psychological functioning (motivation, emotion, memory, etc.). The personality psychologist must tackle the entire beast. The subject matter is the whole person. The discipline addresses questions of reason and passion, human universals and cultural variability, idiosyncratic uniqueness and systematic individual differences. An astute observer of the field, after much reflection on the diverse, conflicting challenges it faces, aptly summed up the state of affairs: “Personality theory is hard” (Bem, 1983, p. 575).

To make matters worse, personality psychologists may have made things harder than they need to be. In 1957, Hall & Lindzey observed that “personality theory has never been deeply embedded in the mainstream of academic psychology” (p. 4). Psychoanalytic, phenomenological, and factor-analytic theories had made little contact with the rest of the field.