Due to its implications concerning subject matters of humanities, the conception of “mental disorder” summons philosophically orientated minds to provide the notion with their contribution. Being an active human being is in every sense featured by a distinctive feeling of individuation and personalization. I would not have been able to write down my thoughts, if I have not had the feeling that I am their owner. Moreover, in spite of all the changes one is subjected to, one’s intuition of being the same individual, and person or self tends to persist through time. This unique feature of human individuals is conceptualized as personal identity over time. Inconsistency is inherent in being human, and for that matter not considered as dangerous with regard to one’s feeling of integrity across time. However, when stipulated in light of mental disorder, the notion of personal identity through time faces an immense threat. “Dissociative Identity Disorder” (D.I.D.) among others, as a type of disorders that strike personality, at least in theoretical sense poses a worry on the idea of sameness, stressed when betting on the persistence of the self by virtue of personal identity over time. Even though the exhaustive explanation of personhood-regarding matters still appears to be out of reach, it is possible to explore if the understanding of the self, personal identity and D.I.D. could be enlightened by analyzing their interrelations.