Personalism posits ultimate reality and value in personhood. It emphasizes the significance, uniqueness and inviolability of the person, as well as the person's essentially relational or communitarian dimension. Personalists investigate the experience, the status, and the dignity of the human being as person, and regard this as the starting-point for all subsequent philosophical analysis. Personalism tends to focus on practical, moral action and ethical questions.
At the center of this personalism stands an affirmation of the dignity of the person, the quality, insisted on already by medieval thinkers, which constitutes the unique excellence of personhood and which gives rise to specific moral requirements. Dignity refers to the inherent value of the person, as a “someone” and not merely “something,” and this confers an absoluteness not found in other beings.
For personalists, human dignity as such does not depend on variables such as native intelligence, athletic ability or social prowess. Nor can it result merely from good conduct or moral merit. It must rather be rooted in human nature itself, so that on the deepest level, despite the variations of moral conduct and the resultant differences in moral character, all members of the species share this dignity.
For the source, head on over to Stanford Encyclopeida of Philosophy.
I cannot think of a better argument for being bipartisan in politics, for recognizing marriage as a union of two persons, for treating each other with dignity and respect. Human dignity is inherent in being human, it is that simple.