Didonians And Souls

How would the Platonic-Cartesian concept of "soul" apply to Poul Anderson's tripartite Didonians? Is a new immortal soul created every time a new entity is formed? When it is no longer possible to form a particular entity, does that entity's soul then enter a hereafter or, in the Platonic scenario, prepare to reincarnate? If, as I was taught at school, only an organism linked to an individual, immaterial and indestructible soul is capable of reason, then the answer to these questions would have to be yes. But the Didonians are unlikely to deduce such a metaphysical conclusion from their inherently overlapping and demonstrably transient way of experiencing life.

CS Lewis argued that materialism cannot explain reason. I reply in section (7) here.

In Robert Heinlein's Starman Jones, a monkey-like alien animal has a limited linguistic capacity. When, with this fictional creature in mind, I suggested to a teacher who was a member of a religious order that, if animals were slightly more intelligent, then we would be able to converse with them, he replied by drawing an absolute doctrinal distinction between species with and without souls. I began to realize that my education and my private reading were giving me contradictory world-views. Another example was the familiar question: which story is true - Adam And Eve or dinosaurs and cavemen?