A philosophical assumption when it comes to the human personality is, quoting Dr. C. George Boeree
Uniqueness vs. universality. Is each person unique, or will we eventually discover universal laws which will explain all of human behavior? Again, more moderate positions are available: Perhaps there are broad rules of human nature with room for individual variation within them; Or perhaps our individuality outweighs our commonalities.
Uniqueness versus Universality
The argument over whether we are all unique individuals (Uniqueness) or if humans are basically similar in their nature (Universality). Gordon Allport, Abraham Maslow, and Carl Rogers were all advocates of the uniqueness of individuals. Behaviorists and cognitive theorists, in contrast, emphasized the importance of universal principles such as reinforcement and self-efficacy.
Interestingly I witness universality dominant around me, even from a behavior point of view the deviations are thin or a are they getting thinner?!!!
…might come back to this topic some other time.