Again browsing near the close of Herzberg’s The Psychology of Philosophers (from the 1920’s), where he lists what he concludes are the key personality traits of the philosopher. I’ve only mentioned a few of these before:

*strong impulses

*intense inhibitions [ADDENDUM: he thinks this comes from “hypersensitivity to feelings of displeasure”]

*high capacity for sublimation (otherwise, the person becomes a neurotic)

*critical intelligence and love of system (otherwise, the person might become an artist instead, since for Herzberg the paranoiac system-loving of the philosopher differs from the “projective mechanism” of the artist, which projects inner psychological processes into the outer world; Herzberg finds this projective mechanism to be weak even in the cases of Plato and Nietzsche, the two greatest literary artists in the history of philosophy)

*rejection of authority (otherwise, the person becomes a religious figure)

*unusual/original structure of the emotional personality (otherwise, the person becomes a scholar)

If Herzberg distinguishes between the philosopher personality and the scientist personality, I must have missed the passage somehow. [ADDENDUM: My mistake, he does address this issue a little later, though he admits he doesn’t have a very good theory about it, just that the scientific personality tends to be more focused on a specific region of entities, such as plants, rocks, or moving physical bodies.]

He seems to be generally Freudian in orientation, though he doesn’t seem to overdo it.