The concept of Person is applied to a subject endowed with powers of reason and free will, and thus is responsible for activities that are not the outcome of physical laws or genetic programming (instinctive behavior). This also means that the Person by its very nature is a subject of rights and duties, with a dignity previous to any social convention.
Since matter is scientifically defined in terms of 4 interactions (forces), we must inquire about the possibility of attributing to its properties and forces the activities proper of a Person. None of those interactions can produce meaning as found in abstract thought. Similarly, the physical forces are unable to explain the freedom exhibited in human behavior, a freedom that is at the root of all social structures with their requirement for responsibility. Such freedom is contrary to the deterministic processes of matter according to the “laws of nature”, and also to the probabilistic fluctuations of Quantum Mechanics: the most obvious quality of a free act is that it doesn’t occur randomly, but it is due to a conscious choice.
The need for a sufficient reason for thought and free will leads to accept a non-material source when matter is unable to explain the full reality of the Person. We have to admit a human spirit, intimately joined to matter in a unity where the ultimate subject is the totality of Man, both for biological activities and for those that transcend physics and chemistry.
The origin of Man on Earth is tied to the stages of evolution of the universe, making Earth a habitable planet, and to the development of life forms through biological change up to the primate level. But the final step, from non-intelligent animal to the Rational Animal, cannot be attributed to random genetic changes. We do not know when or where Man first appeared, but we have cogent reasons to establish the kinship of all living forms on Earth and also the specific unity of the entre human family. This leads to the statement proclaimed in the Declaration of Human Rights signed by the members of the United Nations in 1948, where all human beings are recognized as having the same dignity previous to any social concession.
As a consequence, no Person can ever legitimately be reduced to the level of a “thing”, useful for another individual (slavery) or for the State. This is affirmed by Christian Theology, that holds that Man is the only reason why God created the material Universe and the only answer to why the Universe is not ultimately absurd. The concept of God as a personal Being is also stressed to underline the loving freedom that leads to create other personal entities with whom God wants to share the eternal life and happiness proper of the Creator.