I don't think that the wide spread of the belief in a soul is based on observable facts. If instead we simply ask "why do so many people believe in souls?" then we find that in itself believing in the soul has many social, practical and neurological benefits so proving its existence isn't necessarily important. In our society we have become more and more reliant on scientific facts and so come to doubt anything that is not provable but rationality is nothing but logic applied to a goal and if the goal is happiness then having certain beliefs might be more rational than not having them because of certain benefits it might bring while rejecting all beliefs to live in perpetual doubt might seem rational to someone seeking nothing but fact but irrational for someone aiming to be happy. inevitable doom and a pointless existence might be the ultimate fact-based conclusion but sure makes life a bit gloomy. do we want hard facts or happiness? the type of rationality we choose will be determined by how we answer this question.
@Pikachu well then to put in in a form which more directly answers your question I would say : no, there are no observable facts behind believing in the soul or any traits that can only be explained by the existence of a soul so in this way believing in a soul does not comply with Occam's razor and might be deemed unscientific in that sense unless we look at it another way which would be my previous answer, suggesting it might still be more rational to do so.
@newjaninev2 you kind of took a sentence out of its context. reread what I wrote and I'm sure you will understand why I said that, keeping in mind the subject of this post: are there facts supporting the belief in a soul. I suggest that believing in a soul might serve certain function, some of them neurological or existential, and basically help to increase happiness but rejecting this concept because it isn't fact-based might be more useful for a fact-seeker but not useful if the goal is to be happy since it leads to realising the absurdity of it all.
