[Question:]{.underline} How do I answer someone who affirms that his eternal soul has had past lives?
[Answer:]{.underline} The first point in any response is always to recognize the element of truth in any such statement. The element of truth is that the soul is “eternal”, not in the sense that God is eternal, but meaning, using a Catholic expression, that it is immortal, that is, it that it cannot die or otherwise stop existing. Now this soul that cannot die is always the same soul as it was. It cannot be a different soul or a soul of a different being, and still be an immortal soul.
From this we can exclude reincarnation, which makes the same soul pass through a series of different levels of being, such as animals. If this were the case it would not be the same soul, the same individual, identical to itself. It would be a different soul, that is a principle of a different life that what it was. The reason for this is that the soul is the principle of life, and that the same soul cannot be the principle of two different kinds of life, animal and human.
This person seems to be saying that she has had different human lives. The first and most obvious question is to ask her to prove it, which obviously she cannot do. Any memories that she might have could just be imagination, and they have to be proven by some outside reference point if she is to be taken seriously.
However, the same philosophical argument can be used as with reincarnation. If a soul had had a different life, then it would be a different soul and a different individual being than what it presently is. The one soul cannot change its matter, and become now the form of one body, then of another body; now of one being, then of another being. It would have to be a different individual soul to take a different individual body or being. Hence it could not be the same person who has different lives. The human person is made up of body and soul, so that as soon as you change one you immediately change the other.
This cannot be denied by anybody who acknowledges that man has a spiritual side to him (his faculties of intellect and will), as well as a bodily side. The body and the soul go together, the soul making the body human, and the body being by nature the body of this soul. To say that the two can be in some way separated goes against all the evidence of the senses, which point to the unity of man, body and soul. Hence it is impossible to assert that one person has lived different bodily lives.
Answered by Father Peter Scott, SSPX.