Well it is with just a bit of mental work.
- Is a soul unique?
- When does a human become unique genetically?
- When does it receive its unique identity?
- Can its unique identity be changed into another identity?
- Do humans develop for some period and then receive their identity?
- Or do humans receive their unique identity and this in turn drives its development?
What theory of ensoulment seems to fit the answers to all these questions most simply?
Which theory requires fewer steps and explanations?
The Catholic Church to my knowledge hasn’t made a formal or final pronouncement on the timing of ensoulment. It’s not necessary to defend its position on the human rights of children and abortion.
But how are the data and answers lining up from this mental exercise? Relying only on our reasoning and observation, what is most self evident?