In man, there exists nothing immaterial which subsists (that is a substance). So Unamunomakes a sophistic objection as follows: “How can an unaware reason conclude that our soul is a substance (which subsists, or stays) from the fact that our consciousness of identity persists during the changes of our body? We could just as well speak about the substantial soul of a ship which leaves harbour, loosing today a plank, which is replaced by another one of the same shape and size, loosing then another piece, which is also replaced and so forth, until the same ship comes back with the same shape and the same seaworthy features and everybody recognizes it as the same one.”
Answer: Well, the fact that the ship can be constituted or composed by different matter shows that the ship isn’t mere matter, but also “form”, or structure, or some distribution of these parts or matter (Its shape, which is maintained and restored by the intelligent action of expert men) and, on the given example, although having changed its parts, although having changed its matter not by itself but by the intelligent action of ship-carpenters and naval engineers who repair it, the ship maintains its same shape or structure which, by itself, is a non material element that subsists in the mind of the builders and repair men, as demonstrates the fact that she can be preserved with different matter.
Well, a man’s living form preserves the life of distinct matter (incorporated to men’s body) and this not by the action of an external intelligence (as were the naval carpenters in the case of the ship) but by itself (although it doesn’t exist but by the action of the necessary being, i.e. of God). Therefore, it is a subsistent form (i.e. a form that subsists by itself versus the ships form or structure that persists by the intelligent action of naval carpenters). Hereby, we don’t pretend to demonstrate that it is immortal, but only that in man there exists an immaterial part: the form or soul. But, since it is persistent or subsisting by itself, it could also be immortal, as the philosopher Tresmontantsuggests: “The organisms form or structure is not like those of the machine. The organism’s form subsists whilst every conforming material element is renewed. In the case of a man-made object, form doesn’t subsist. It is merely external. It isn’t immanent. It isn’t active. It is not substance either. If I break a statue or a machine, I really break its form. No form’s immortality exists in the case of a machine or statue; at most, in the mind of the artist or engineer who conceives or remembers it (in our example, in the mind of the naval engineer or ship carpenter).
On the other hand, if I cut a planarian (an invertebrate animal) in two pieces, each half will bring a new planarian. If I cut myself, I’m able to regenerate at least the disappeared epidermis. An indeed twenty, forty or eighty years later, I’ll be the same person. I subsist by myself, although the matter which gave shape to myself has steadily been renovated” And he goes on as follows:
“According to reports given to us by last century biologists, we can say that there is apparently no difficulty in admitting that the soul (a man’s form) can subsist after having given shape to the body (when it separates the body, when we die), since, according to the experiments of modern science, we state a relative independence between the subsisting soul and the conformed matter that is renewed (the matter recycled in our body by nourishment and dejection).
If there were a total adjustment between form and matter, as in the case of the statue or the machine, or of any other object made by man, if the form’s subsistence depended on the integrity of the gathered materials, if form didn’t witness any independent existence, it would be then difficult to speak about a possible immortality of the soul. Nevertheless, in the case of a living organism, the soul is a substance (the soul or form subsists). Its actual and relative independence from integrated matter, vouches for its ability to survive without conforming matter. Indeed there is no contradiction or nonsense in such hypotheses”.
In order to see that there exists something immaterial in man, lets mention a text from Kahane, a French biologist, who was no believer: “The grounds of individuality of each living being are in its structure’s persistence or, to be more precise, in the structure’s permanency “. (Just before, the author has told us that in a living organism everything is renewed “in such a way, that, from an instant to the next, there isn’t any organism which is constituted by the same matter …”). Therefore, what assures the persistence of the living individual is its “structure”, which is neither this nor that matter.
We can call it form, soul or structure, but the fact is that an immaterial element persists in man, which makes the individual remain the same, although its body changes in matter.