Many nomothetic theories have antecedents in classical descriptions, and many can ultimately be linked to Hippocrates (470-410 BC) who defined the four humors: yellow bile, black bile, phlegm, and blood. This system had two dimensions (hot and cold, and dry and wet) on which all people could be placed, with different individuals being characteristically hotter or colder, and wetter or drier. These terms still exist in everyday speech as choleric, melancholic, phlegmatic, and sanguine, but in personality theories the humors are now referred to as “traits.” Five traits (extraversion, neuroticism, agreeableness, conscientiousness, and openness) are widely accepted as defining the essential descriptive framework that best captures individual variation. Idiographic theories have often drawn on the same tradition, but in the modern era are much more closely associated with clinical work and individual psychotherapy. The clinic is where many of them were first developed, and the best known is Sigmund Freud's work on psychoanalysis.
The personality literature is very diverse in terms of its theoretical and methodological assumptions, and most of the critical debates from across the social sciences are to be found here. One important critical line that intervenes in these debates concerns how much of the individual's behavior is to be understood in terms of personality. At one time, grand claims were made for the range and types of behavior that personality theories could explain, but now personality theorists are more circumspect, and recognize the significance of other social characteristics such as age, gender, and race and ethnicity, or other personal determinants of behavior, such as attitude.
Apart from the application of idiographic accounts in psychotherapy, personality theories from the nomothetic tradition are of interest and value to those selecting people for different roles in organizations and teams, or advising individuals on career choices. Personality tests such as the Myers-Briggs test, which identifies four dimensions akin to the five traits mentioned above, is typical in this regard, and in over sixty years of use and development it has a reasonable degree of reliability and validity in many eyes.
DAVID GOOD