Soul can be our colloquial word to call a collection of Information linked with Causal relations. But basically,to mean it as something that is "separate" and "unrelated and outside" "this World" is not true. Information cannot be destroyed. Our minds,Thoughts,memories,etc are actually from Atomic/Molecular and sometimes Subatomic/Quantum level. There is perfect and obvious evidence for this. So as a Transhumanist,I think Soul is as a whole a colloquial term to say information linked with Causal connections.