Abstract: The author examines conflicting conceptions of human mentation and human mental development, an area representing an overlapping interest in psychoanalysis and philosophy. Focus is on the question of whether there is any essential aspect to the mind or whether everything is relative, intersubjective, and formed by the culture in which one lives. The irrational and noncognitive aspects of mental life are outlined from the thought of Freud, Nietzsche, and Schopenhauer and their views of the essential springs of psychic activity. The ramifications of these various conflicting conceptions for the practice of psychoanalytic therapy are outlined. The question is addressed of whether it will ever be possible, as in the Enlightenment dream, to improve the human condition and put an end to human violence. The answers to this question are shown to differ depending on the various conceptions of human mentation and human mental development involved. No conclusions are reached; the issues remain unsettled in our time.