Although third-force psychology became very popular during the 1960s and 1970s, its popularity began to wane in the 1980s. Like behaviorism and psychoanalysis, however, third-force psychology remains influential in contemporary psychology (see, for example, Clay, 2002). Third-force psychology contrasts vividly with most other types because it does not assume determinism in explaining human behavior. Rather, it assumes that humans are free to choose their own type of existence. Instead of attributing the causes of behavior to stimuli, drive states, genetics, or early experience, third-force psychologists claim that the most important cause of behavior is subjective reality. Because these psychologists do not assume determinism, they are not scientists in the traditional sense, and they make no apology for that. Science in its present form, they say, is not equipped to study, explain, or understand human nature. A new science is needed, a human science. A human science would not study humans as the physical sciences study physical objects. Rather, it would study humans as aware, choosing, valuing, emotional, and unique beings in the universe. Traditional science does not do this and must therefore be rejected.