The article argues against determinism in modern science of psychology which claims that problems of the soul could be resolved through applied mathematical formulas (Fechner). Additional objections are raised to in determinism in the context of which philosophers, like Nietzsche and Schopenhauer, founded their philosophical systems on an arbitrary will. Ιnstead the author endorses the assertion that it' s personality through consciousness-- its guiding instrument-- that organizes human soul and finally ensures human freedom of will. For the above statement to be validated a number of scholars are listed and briefly annotated (William Stern, Jung, Jaspers, Politzer and the psychiatrist Minkowski ).